Luminescent materials and their manufacturing methods

Abstract

This invention provides a luminescent material comprising a high-brightness red-emitting phosphor. The luminescent material comprises a fluoride phosphor having a first composition, the first composition comprising: an alkali metal containing K, Si, Al, Mn, and F. For the first composition, with the total molar number of the alkali metal set to 2, the total molar number of Si, Al, and Mn is 0.9 or more and 1.1 or less, the molar number of Al is greater than 0 and less than 0.1, the molar number of Mn is greater than 0 and less than 0.2, and the molar number of F is 5.5 or more and less than 6.0. The fluoride phosphor has a cubic crystal structure with a lattice constant of 0.8138 nm or more.

Description

Technical Field

[0001] This application relates to luminescent materials and methods for manufacturing the same. Background Technology

[0002] Various light-emitting devices combining light-emitting elements and phosphors have been developed and are widely used in lighting, automotive lighting, displays, and LCD backlights. For example, phosphors used in light-emitting devices for LCD backlights require high color purity, i.e., a narrow half-width at half-maximum (WWHM) of the emission peak. As a red-emitting phosphor with a narrow WWHM, Japanese Patent Application Publication No. 2012-224536 discloses, for example, a fluoride phosphor having a composition represented as K2SiF6:Mn. Summary of the Invention

[0003] The problem that the invention aims to solve

[0004] For phosphors used in light-emitting devices, in addition to a narrow half-width at half-maximum (WWHM) of the emission peak, increased brightness is also required. For example, there is still room for improvement in brightness for the fluoride phosphor disclosed in Patent Document 1. Therefore, one objective of this disclosure is to provide a light-emitting material comprising a phosphor that emits red light with high brightness.

[0005] Problem Solving Methods

[0006] The first embodiment is a luminescent material comprising a fluoride phosphor having a first composition, wherein the first composition comprises: an alkali metal containing K, Si, Al, Mn, and F. For the first composition, with the total molar number of the alkali metal set to 2, the total molar number of Si, Al, and Mn is 0.9 or more and 1.1 or less, the molar number of Al is greater than 0 and less than 0.1, the molar number of Mn is greater than 0 and less than 0.2, and the molar number of F is 5.5 or more and less than 6.0. The fluoride phosphor has a cubic crystal structure with a lattice constant of 0.8138 nm or more.

[0007] The second method relates to a luminescent material comprising a fluoride phosphor having a first composition, wherein the first composition comprises: an alkali metal containing K, Si, Al, Mn, and F. For the first composition, with the total molar number of the alkali metal set to 2, the total molar number of Si, Al, and Mn is 0.9 or more and 1.1 or less, the molar number of Al is greater than 0 and less than 0.1, the molar number of Mn is greater than 0 and less than 0.2, and the molar number of F is 5.5 or more and less than 6.0. The aforementioned fluoride phosphor exhibits infrared absorption spectra at 590 cm⁻¹. -1 Above and 610cm -1 The following wavenumber range has absorption peaks.

[0008] The third method relates to a method for manufacturing a luminescent material, the method comprising: preparing first fluoride particles having a second composition, the second composition comprising: an alkali metal containing K, Si, Mn and F, wherein when the total molar number of the alkali metal is set to 2, the total molar number of Si and Mn is 0.9 or more and 1.1 or less, the molar number of Mn is greater than 0 and 0.2 or less, and the molar number of F is 5.5 or more and less than 6.0; preparing second fluoride particles having a third composition, the third composition comprising: an alkali metal containing K, Al and F, wherein when the molar number of Al is set to 1, the total molar number of the alkali metal is 2 or more and 3 or less, and the molar number of F is 5 or more and 6 or less; and subjecting a mixture of the first fluoride particles and the second fluoride particles to a first heat treatment in an inactive gas atmosphere at a temperature range of 600°C or more and 780°C or less to obtain a first heat-treated product.

[0009] The effects of the invention

[0010] According to one aspect of this application, a luminescent material comprising a high-brightness red-emitting phosphor can be provided. Attached Figure Description

[0011] Figure 1 This is a flowchart illustrating an example of the process sequence in a method for manufacturing fluoride phosphors.

[0012] Figure 2 This is a schematic cross-sectional view showing an example of a light-emitting device containing a fluoride phosphor.

[0013] Figure 3 It is the infrared absorption spectrum of a fluoride phosphor.

[0014] Figure 4 This is an example of a scanning electron microscope (SEM) image of the fluoride fluorophore in Comparative Example 1.

[0015] Figure 5 This is an example of a SEM image of the fluoride phosphor from Example 3.

[0016] Figure 6 It is the infrared absorption spectrum of the first and second fluoride particles.

[0017] Figure 7 This is an example of a cross-sectional SEM image of the fluoride phosphor in Example 17.

[0018] Figure 8 This is an example of a SEM image of the fluoride phosphor from Example 17. Detailed Implementation

[0019] In this specification, the term "process" includes not only independent processes, but also processes that cannot be clearly distinguished from others, as long as they achieve the desired purpose of the process. Furthermore, regarding the content of each component in the composition, if multiple substances conforming to each component are present in the composition, unless specifically stated otherwise, it refers to the total amount of those substances present in the composition. Moreover, the upper and lower limits of the numerical ranges described in this specification can be arbitrarily selected and combined. In this specification, the relationship between color names and chromaticity coordinates, and the relationship between the wavelength range of light and the color names of monochromatic light, are based on JIS Z8110. The half-width of a phosphor, luminescent material, or luminescent element refers to the wavelength width of the emission spectrum where the luminescence intensity is 50% relative to the maximum luminescence intensity (full width at half maximum; FWHM). The median particle size of a phosphor or luminescent material is the volume-based median particle size, which refers to the particle size corresponding to 50% of the cumulative volume from the smallest diameter side in the volume-based particle size distribution. The particle size distribution of phosphors or luminescent materials can be determined using a laser diffraction particle size distribution measuring device. Furthermore, in this specification, in the formulas representing the composition of the first and second luminescent materials, multiple elements separated by commas (,) indicate that the composition contains at least one of these multiple elements. Additionally, in the formulas representing the composition of phosphors or luminescent materials, the part before the colon (:) represents the parent crystal, and the part after the colon (:) represents the activating element. Hereinafter, embodiments of the present invention will be described in detail. The embodiments shown below exemplify fluoride phosphors, luminescent materials, methods for manufacturing them, and luminescent devices for embodying the technical concept of the present invention. The present invention is not limited to the fluoride phosphors, luminescent materials, methods for manufacturing them, and luminescent devices shown below.

[0020] Luminescent materials

[0021] The luminescent material comprises a fluoride phosphor having a first composition, which includes: an alkali metal containing potassium (K), silicon (Si), aluminum (Al), manganese (Mn), and fluorine (F). The fluoride phosphor has a cubic crystal structure with a lattice constant of 0.8138 nm or higher. Furthermore, the fluoride phosphor exhibits high luminescence intensity in the infrared absorption spectrum at 590 cm⁻¹. -1 Above and 610cm -1The following wavenumber ranges exhibit absorption peaks. For the first composition, with the total molar number of alkali metals set to 2, the total molar number of Si, Al, and Mn is 0.9 or more and 1.1 or less, the molar number of Al is greater than 0 and less than 0.1, the molar number of Mn is greater than 0 and less than 0.2, and the molar number of F is 5.5 or more and less than 6.0. The Mn contained in the fluoride phosphor may include tetravalent Mn ions. The fluoride phosphor can be manufactured, for example, by the fluoride phosphor manufacturing method described later.

[0022] Fluoride phosphors contain Si and Al, with Al in a specific proportion, and have a cubic crystal structure with a lattice constant greater than a given value, thus exhibiting higher brightness. This can be considered, for example, as follows: This can be attributed to the fact that by partially replacing Si with Al in the crystal structure of the fluoride phosphor, the deficiency of F in the crystal structure is compensated, and the crystal structure is stabilized. Furthermore, by partially replacing Si with Al in the crystal structure of the fluoride phosphor, a lattice constant greater than a given value is exhibited. Moreover, because fluoride phosphors contain Al in their crystal structure, they exhibit, for example, peaks originating from Al-F bonds in their infrared absorption spectra.

[0023] In the first composition of the fluoride phosphor, the ratio of the total molar number of Si, Al, and Mn to the total molar number of alkali metals in the composition can be, for example, 0.9 or more and 1.1 or less, preferably 0.95 or more and 1.05 or less, 0.97 or more and 1.03 or less, or 1.0. Furthermore, the ratio of the molar number of Al to the total molar number of alkali metals can be, for example, greater than 0 and less than 0.1, preferably greater than 0 and less than 0.06, greater than 0 and less than 0.03, 0.002 or more and less than 0.02, or 0.003 or more and less than 0.015. Moreover, it can be 0.005 or more and less than 0.06, or 0.01 or more and less than 0.03. Additionally, the ratio of the molar number of Mn to the total molar number of alkali metals can be, for example, greater than 0 and less than 0.2, preferably 0.005 or more and less than 0.15, 0.01 or more and less than 0.12, or 0.015 or more and less than 0.1. Furthermore, in one embodiment, the ratio of the number of moles of F to the total number of moles of alkali metals can be, for example, 5.9 or more and 6.1 or less, preferably 5.9 or more and 6.1 or less, 5.92 or more and 6.05 or less, or 5.95 or more and 6.025 or less. In another embodiment, the ratio of the number of moles of F to the total number of moles of alkali metals can be, for example, 5.5 or more and less than 6.0, preferably 5.9 or more and less than 6.0, 5.96 or more and 5.995 or less, or 5.97 or more and 5.99 or less. In the first composition, the ratio of the number of moles of Si to the total number of moles of alkali metals can be, for example, 0.7 or more and 1.1 or less, preferably 0.8 or more and 1.03 or less, 0.85 or more and 1.01 or less, or 0.92 or more and less than 0.95. In the first composition, the ratio of the molar number of Al to the molar number of Si can be, for example, 0.001 or more and 0.14 or less, preferably 0.002 or more and 0.04 or less, or 0.003 or more and 0.015 or less. The composition of the fluoride phosphor can be determined, for example, by inductively coupled plasma (ICP) luminescence spectrophotometry.

[0024] Furthermore, the first composition of the fluoride phosphor can satisfy the following numerical ranges. The ratio of the total moles of Si, Al, and Mn contained in the composition to the total moles of alkali metals² can be, for example, 0.9 or more, 0.95 or more, or 0.97 or more, and can also be 1.1 or less, 1.05 or less, 1.03 or less, or 1.0. Furthermore, the ratio of the moles of Al to the total moles of alkali metals² can be, for example, greater than 0, and can be 0.002 or more, 0.003 or more, 0.005 or more, or 0.01 or more, and can also be 0.06 or less, 0.03 or less, 0.02 or less, or 0.015 or less. Furthermore, the ratio of the moles of Mn to the total moles of alkali metals² can be, for example, greater than 0, and can be 0.005 or more, 0.01 or more, or 0.015 or more, and can also be 0.2 or less, 0.15 or less, 0.12 or less, or 0.1 or less. Furthermore, the ratio of the number of moles of F to the total number of moles of alkali metals can be, for example, 5.5 or more, 5.9 or more, 5.92 or more, 5.95 or more, or 5.97 or more, and can also be 6.1 or less, 6.05 or less, 6.025 or less, less than 6.0, 5.998 or less, 5.995 or less, or 5.99 or less. Similarly, the ratio of the number of moles of Si to the total number of moles of alkali metals can be, for example, 0.7 or more, 0.8 or more, 0.85 or more, or 0.92 or more, and can also be 1.1 or less, 1.03 or less, 1.01 or less, less than 1, or less than 0.95. The ratio of the number of moles of Al to the number of moles of Si can be, for example, 0.001 or more, 0.002 or more, or 0.003 or more, and can also be 0.14 or less, 0.04 or less, or 0.015 or less.

[0025] Fluoride phosphors may have a composition represented by the following formula (I) as the first component.

[0026] M2[Si p Al q Mn r F s (I)

[0027] In formula (I), M can represent an alkali metal and includes at least K. Mn can be a tetravalent Mn ion. p, q, r and s can satisfy 0.9≤p+q+r≤1.1, 0<q≤0.1, 0<r≤0.2, 5.9≤s≤6.1 or 5.5≤s<6.0. Preferred values ​​could be 0.95≤p+q+r≤1.05, 0.97≤p+q+r≤1.03 or p+q+r=1.0, 0<q≤0.06, 0<q≤0.03, 0.002≤q≤0.02 or 0.003≤q≤0.015, or 0.005≤q≤0.06 or 0.01≤q≤0.03, 0.005≤r≤0.15, 0.01≤r≤0.12 or 0.015≤r≤0.1, 5.92≤s≤6.05 or 5.95≤s≤6.025, or 5.9≤s<6.0, 5.96≤s≤5.995 or 5.97≤s≤5.99.

[0028] In addition, fluoride phosphors may have a first theoretical composition represented by the following formula (Ia).

[0029] M2(Si,Al)F6:Mn(Ia)

[0030] In formula (Ia), M can represent an alkali metal and includes at least K. Mn can be a tetravalent Mn ion.

[0031] The alkali metal in the composition of the fluoride phosphor and the first and second fluoride particles described later includes at least K, and may include at least one selected from lithium (Li), sodium (Na), rubidium (Rb), and cesium (Cs). The ratio of the molar number of K to the total molar number of the alkali metal in the composition may be, for example, 0.90 or more, preferably 0.95 or more, or 0.97 or more. The upper limit of the molar number ratio of K may be, for example, 1 or less, or 0.995 or less. In the first composition, a portion of the alkali metal may be replaced by ammonium ions (NH4+). + When a portion of the alkali metal is replaced by ammonium ions, the ratio of the number of moles of ammonium ions to the total number of moles of the alkali metal in the composition can be, for example, 0.10 or less, preferably 0.05 or less, or 0.03 or less. The lower limit of the ratio of the number of moles of ammonium ions can be, for example, greater than 0, preferably greater than 0.005.

[0032] Fluoride phosphors can contain cubic crystal structures, or they can contain crystal structures of other crystal systems besides cubic, such as hexagonal, and can be substantially composed solely of cubic crystal structures. Here, "substantially" means that the content of crystal structures other than cubic crystal systems is less than 0.5%. When a fluoride phosphor contains a cubic crystal structure, its lattice constant can be, for example, 0.8138 nm or more, preferably 0.8140 nm or more, or 0.8143 nm or more. The upper limit of the lattice constant can be, for example, 0.8150 nm or less. The cubic crystal structure of the fluoride phosphor and its lattice constant can be evaluated by measuring the X-ray diffraction pattern of the fluoride phosphor. The X-ray diffraction pattern can be measured, for example, using CuKα rays (λ = 0.15418 nm, tube voltage 40 kV, tube current 40 mA) as the X-ray source.

[0033] In infrared absorption spectroscopy, fluoride phosphors, for example, can be observed at 590 cm⁻¹. -1 Above and 610cm -1 The following wavenumber range has an absorption peak, preferably at 593 cm⁻¹. -1 Above and 607cm -1 Below, or 595cm -1 Above and 605cm -1 The following wavenumber ranges exhibit absorption peaks. It can be assumed that the absorption peaks within a given wavenumber range originate from Al-F bonds in a crystal structure, such as a cubic system. Infrared absorption spectra can be determined, for example, by total internal reflection (ATR).

[0034] Fluoride phosphors can have irregularities, grooves, etc., on their particle surfaces. It can be understood that by introducing Al into the crystal structure of a fluoride phosphor, the crystal structure changes, forming irregularities, grooves, etc., on the particle surface. The state of the particle surface can be evaluated, for example, by measuring the angle of repose of the powder formed by the fluoride phosphor. The angle of repose of the powder formed by the fluoride phosphor can be, for example, 60° or less, preferably 55° or less, or 50° or less. The lower limit of the angle of repose is, for example, 30° or more. The angle of repose of the powder can be measured, for example, using a powder property measuring instrument (e.g., an ABD powder property measuring instrument, manufactured by Tsutsui Rikikaku Equipment Co., Ltd.).

[0035] Furthermore, the surface condition of the fluoride phosphor particles can be evaluated, for example, by measuring the dispersion and bulk density of the powder formed from the fluoride phosphor. For a fluoride phosphor with a given dispersion or a given bulk density, by suppressing the aggregation of the powder formed from the fluoride phosphor, the powder becomes easier to handle during the manufacture of the light-emitting device, thus improving the operability of the manufacturing process. In addition, since the filling density of the fluoride phosphor can be increased in the light-emitting device, an increase in the luminous flux of the light-emitting device can also be expected. The dispersion of the powder formed from the fluoride phosphor can be, for example, 2.0% or more, preferably 5.0% or more, 15% or more, or 20% or more. The upper limit of the dispersion can be, for example, 75% or less, 60% or less, or 50% or less. The dispersion of the powder can be measured, for example, using a powder property measuring instrument (e.g., an ABD powder property measuring instrument, manufactured by Tsutsui Rikikaku Equipment Co., Ltd.). Specifically, the sample is dropped from the hopper into a dispersibility receiver. The weight of the sample remaining in the receiver is subtracted from the weight of the dropped sample. The resulting value is divided by the weight of the dropped sample, and the dispersibility is calculated as a percentage.

[0036] The bulk density of powders formed from fluoride phosphors can be, for example, 1.00 g·cm³. -3 The above, preferably 1.05 g·cm³ -3 Above, 1.10 g·cm -3 Above or 1.15 g·cm -3 The above. The upper limit of bulk density can be, for example, 1.50 g·cm³. -3 Below, 1.40 g·cm -3 Below or 1.30 g·cm -3 The bulk density can be determined, for example, by using a graduated cylinder as a standard measurement method. The bulk density will be explained in detail below. Generally, the bulk density of a powder is determined by measuring the volume of a known weight of powder sample placed in a graduated cylinder, or by measuring the weight of a known volume of powder sample entering the container through a volumetric meter, or by using a dedicated measuring container.

[0037] The following describes, for example, the method using a graduated cylinder. First, prepare a sufficient quantity of sample for the measurement, sieving it as needed. Next, add the necessary quantity of sample to a dry graduated cylinder of a given capacity. Here, the upper surface of the sample should be leveled as needed. These operations should be performed smoothly so as not to affect the physical properties of the sample. Then, read the volume to the smallest graduation unit, calculate the weight of the sample per unit volume, and thus determine the bulk density. For this bulk density, it is preferable to repeat the measurement, more preferably to perform multiple measurements, and obtain the arithmetic mean of these measurements.

[0038] From the viewpoint of improving brightness, the median particle size of the fluoride phosphor in the volume reference can be, for example, 10 μm or more and 90 μm or less, preferably 15 μm or more and 70 μm or less, or 20 μm or more and 50 μm or less. From the viewpoint of improving brightness, the particle size distribution of the fluoride phosphor can, for example, exhibit a particle size distribution with a single peak, preferably exhibiting a particle size distribution with a single peak with a narrow distribution width. Specifically, in the volume reference particle size distribution, when the particle size corresponding to 10% of the volume accumulation from the smallest particle size side is defined as D10, and the particle size corresponding to 90% of the volume accumulation is defined as D90, the ratio of D90 to D10 (D90 / D10) can be 3.0 or less.

[0039] Fluoride phosphors, for example, are phosphors activated with tetravalent Mn, which absorb light in the short wavelength region of the visible spectrum and emit red light. The excitation light can be mainly blue light, and the peak wavelength of the excitation light can be, for example, in the wavelength range of 380 nm to 485 nm. The peak wavelength of the emission spectrum of the fluoride phosphor or luminescent material can be, for example, in the wavelength range of 610 nm to 650 nm. The half-width at half-maximum (WWHM) of the emission spectrum of the fluoride phosphor or luminescent material can be, for example, less than 10 nm.

[0040] The luminescent material may comprise a fluoride phosphor and an oxide disposed on at least a portion of the surface of the fluoride phosphor. The oxide may comprise at least one selected from silicon (Si), aluminum (Al), titanium (Ti), zirconium (Zr), tin (Sn), and zinc (Zn). The oxide content in the luminescent material may be more than 2% by mass and less than 30% by mass relative to the luminescent material.

[0041] By coating at least a portion of the surface of a fluoride phosphor with a specific composition using a given amount of a specific oxide, the moisture resistance of the luminescent material is improved, for example. This improves the reliability of a luminescent device comprising a luminescent material containing a fluoride phosphor and a resin. For example, it can suppress the reduction in the mass of the luminescent component in high-temperature or high-humidity environments. The reduction in the mass of the luminescent component is considered primarily a reduction in the amount of resin. It is understood that by directly contacting the fluoride phosphor with the resin in a high-temperature or high-humidity environment, a reaction occurs, causing the dispersion of decomposition products resulting from the breaking of some interatomic bonds in the resin. By coating the fluoride phosphor with a given amount of an oxide considered to have higher chemical stability than the fluoride phosphor, direct contact between the resin and the fluoride phosphor can be suppressed, inhibiting the reaction between them and maintaining the amount of resin. The resin also functions as a protective component for the luminescent material; therefore, it is understood that the reduction in the amount of resin makes it more susceptible to the effects of a humid external environment, promoting the deterioration of the luminescent material. Furthermore, due to the reduction in the amount of resin, for example… Figure 1The shape of the light-emitting surface of the fluorescent component in the illustrated light-emitting device is deformed, thereby increasing the likelihood of total internal reflection of light from inside the device. Therefore, it can be assumed that the amount of light exiting the device is reduced, and the luminous flux of the device decreases.

[0042] The luminescent material may contain an oxide disposed on at least a portion of the surface of the fluoride phosphor. The oxide may be a film covering the surface of the fluoride phosphor, or it may be disposed as an oxide layer on the surface of the fluoride phosphor. Furthermore, the oxide film covering the surface of the fluoride phosphor is not limited to being completely crack-free; cracks may exist in a portion of the oxide film covering the surface of the fluoride phosphor to the extent necessary to achieve the desired effect. While it is preferable that the oxide film completely covers the entire surface of the fluoride phosphor, a portion of the oxide film may be partially missing, exposing a portion of the fluoride phosphor surface to the extent necessary to achieve the desired effect. The oxide-based coverage of the fluoride phosphor in the luminescent material may be, for example, 50% or more, preferably 80% or more, or 90% or more. The oxide-based coverage of the fluoride phosphor is calculated as the ratio of the area covered by oxide to the surface area of ​​the fluoride phosphor.

[0043] The oxide may contain at least one selected from Si, Al, Ti, Zr, Sn, and Zn. That is, the oxide may contain at least one selected from silicon oxide (e.g., SiOx, where x can be 1 or more and 2 or less, preferably 1.5 or more and 2 or less, or about 2), aluminum oxide (e.g., Al2O3), titanium oxide (e.g., TiO2), zirconium oxide (e.g., ZrO2), tin oxide (e.g., SnO, SnO2, etc.), and zinc oxide (e.g., ZnO), and may contain at least silicon oxide. The oxide may contain only one type or more types.

[0044] Compared to the luminescent material, the oxide content in the luminescent material can be 2% by mass or more and 30% by mass or less, preferably 5% by mass or more and 20% by mass or less, or 8% by mass or more and 15% by mass or less. Regarding the oxide content in the luminescent material, for example, in the case of silicon oxide, the amounts of each constituent element in the oxide-coated fluoride phosphor and the fluoride phosphor without oxide are analyzed separately using inductively coupled plasma (ICP) luminescence spectrophotometry, and the molar ratio of each constituent element is calculated with the molar number of alkali metals being 2. The difference in the molar ratio of silicon before and after oxide coating is converted into the mass of silicon oxide (e.g., SiO2), and the mass of the oxide-coated fluoride phosphor (luminescent material) is set to 100% by mass to calculate the silicon oxide (e.g., SiO2) content. By keeping the oxide content within the above range, the reliability of the luminescent device can be further improved.

[0045] In luminescent materials containing fluoride phosphors, the fluoride phosphors may be covered by an oxide layer. The average thickness of the oxide layer covering the fluoride phosphor may be, for example, 0.1 μm or more and 1.8 μm or less, preferably 0.15 μm or more and 1.0 μm or less, or 0.2 μm or more and 0.8 μm or less. The average thickness of the oxide layer in the luminescent material may be, for example, a measured average thickness obtained by actually measuring the thickness of layers identified as oxide layers at multiple locations in a cross-sectional image of the luminescent material and using this thickness as an arithmetic mean. Alternatively, the average thickness of the oxide layer in the luminescent material may be a theoretical thickness calculated based on the Kα ray intensity ratio of element F, as described later. The theoretical thickness can be calculated using the CXRO (The Center for X-Ray Optics) database, based on the ratio of the peak intensity of Kα rays of element F in the oxide-coated fluoride phosphor (luminescent material) to the peak intensity of Kα rays of element F in the uncoated fluoride phosphor. The theoretical thickness can be calculated as a value obtained by averaging the presence of defects such as cracks and gaps in the oxide layer.

[0046] In luminescent materials, fluoride phosphors are coated with oxides, thus the peak intensity of characteristic X-rays from the fluoride phosphor decreases accordingly with the amount of oxide coating the fluoride phosphor. Therefore, for luminescent materials containing fluoride phosphors, the oxide-based coating state can be evaluated by assessing the peak intensity of characteristic X-rays from the fluoride phosphor. Specifically, in X-ray fluorescence (XRF) elemental analysis, the ratio of the peak intensity of Kα rays of element F in the luminescent material to the peak intensity of Kα rays of element F in the fluoride phosphor can be, for example, 80% or less, preferably 70% or less, or 60% or less. The lower limit of the peak intensity ratio can be, for example, 20% or more. By ensuring that the ratio of the peak intensity of Kα rays of element F in the luminescent material is within the above range, the reliability of the luminescent device can be improved more effectively.

[0047] In luminescent materials, rare-earth phosphates can be deposited on at least a portion of the surface of a fluoride phosphor. This tends to further improve the hygrothermal resistance of the luminescent material. The rare-earth phosphates deposited on the surface of the fluoride phosphor can be attached to at least a portion of the surface of the fluoride phosphor in the form of particles, or they can be coated on at least a portion of the surface of the fluoride phosphor in the form of a film or layer. Preferably, they can be attached to the surface of the fluoride phosphor in the form of particles.

[0048] In luminescent materials, rare-earth phosphates can be deposited on at least a portion of the surface of a fluoride phosphor, and the fluoride phosphor is coated with oxides interposed between the rare-earth phosphates. This tends to further improve the hygrothermal resistance of the luminescent material. Furthermore, the adhesion of the oxide to the fluoride phosphor is improved, and there is a tendency to further improve the coating properties based on the oxide.

[0049] Rare earth phosphates may contain at least one rare earth element selected from lanthanum (La), cerium (Ce), dysprosium (Dy) and gadolinium (Gd), and preferably may contain at least lanthanum.

[0050] The content of rare earth phosphates in the luminescent material, in terms of the content of rare earth elements, can be, for example, 0.1% by mass or more and 20% by mass or less, preferably 0.2% by mass or more and 15% by mass or more and 0.3% by mass or less and 10% by mass or less.

[0051] For luminescent materials obtained by coating fluoride phosphors with at least one of oxides and rare earth phosphates, even after coating with at least one of oxides and rare earth phosphates, the surface of the fluoride phosphor may have irregularities, grooves, etc. As a result, due to the irregularities and grooves on the surface of the luminescent material, the contact area between the particles of the luminescent material is reduced, and the aggregation of the luminescent material is suppressed. Therefore, it is possible to more uniformly disperse the particles of the luminescent material in the resin composition during the manufacture of the luminescent device. Furthermore, for example, when a disperser is used during the manufacture of the luminescent device, it is less likely to cause problems such as luminescent material clogging inside the disperser needles. Moreover, it is possible to obtain a luminescent device with less aggregation of the luminescent material and less color deviation.

[0052] The surface of the luminescent material can be further treated with a coupling agent. Specifically, a surface treatment layer containing functional groups derived from the coupling agent can be deposited on the surface of the luminescent material. By depositing a surface treatment layer on the surface of the luminescent material, for example, the moisture resistance of the luminescent material is further improved.

[0053] Examples of functional groups derived from coupling agents include silyl groups having an aliphatic group having 1 to 20 carbon atoms, with silyl groups having an aliphatic group having 6 to 12 carbon atoms being more preferred. The functional group derived from the coupling agent can be a single type or a combination of two or more types.

[0054] Examples of coupling agents include silane coupling agents, titanium coupling agents, and aluminum coupling agents. Examples of silane coupling agents include, for instance, alkyltrialkoxysilanes such as methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, and decyltriethylsilane; aryltrialkoxysilanes such as phenyltrimethoxysilane and styryltrimethoxysilane; vinyltrimethoxysilanes such as vinyltrialkoxysilane; aminoalkyltrialkoxysilanes such as 3-aminopropyltriethoxysilane; and epoxypropoxyalkyltrialkoxysilanes such as 3-epoxypropoxypropyltrimethoxysilane, etc., and at least one of these can be selected. From the perspective of easy availability, silane coupling agents are preferred as coupling agents.

[0055] Methods for manufacturing luminescent materials

[0056] Figure 1This is a flowchart illustrating an example of the steps in a method for manufacturing a luminescent material. The method may include: preparing first fluoride particles (S101); preparing second fluoride particles (S102); and performing a first heat treatment to obtain a first heat-treated product (S103). The preparation of the first fluoride particles (S101) and the preparation of the second fluoride particles (S102) may be performed either first or simultaneously. Furthermore, the method may include cleaning (S104) after the first heat treatment (S103), and may further include a second heat treatment after cleaning (S104) to obtain a second heat-treated product (S105). Alternatively, the method may perform a second heat treatment without cleaning after the first heat treatment (S103) to obtain a second heat-treated product (S105).

[0057] A method for manufacturing a luminescent material includes: a first preparation step for preparing first fluoride particles; a second preparation step for preparing second fluoride particles; and a first heat treatment step for subjecting a mixture of the first and second fluoride particles to a first heat treatment in an inactive gas atmosphere at a temperature range of 600°C to 780°C to obtain a first heat-treated product. The first fluoride particles have a second composition comprising an alkali metal containing potassium (K), Si, Mn, and F. For the second composition, when the total molar number of the alkali metal is set to 2, the total molar number of Si and Mn is 0.9 or more and 1.1 or less, the molar number of Mn is greater than 0 and less than 0.2, and the molar number of F is 5.9 or more and 6.1 or less, or 5.5 or more and less than 6.0. The second fluoride particles have a third composition comprising an alkali metal containing potassium (K), Al, and F. For the third composition, when the molar number of Al is set to 1, the total molar number of the alkali metal is 2 or more and 3 or less, and the molar number of F is 5 or more and 6 or less.

[0058] By heat-treating a mixture of first fluoride particles containing Mn as the activating element and second fluoride particles containing Al at a specific temperature, Al can be introduced into the composition of the first fluoride particles, thus creating a fluoride phosphor exhibiting high brightness. This can be considered, for example, as follows: It can be thought that by heat-treating the mixture of the first and second fluoride particles at a higher temperature, the second fluoride particles can be introduced into the first fluoride particles. By replacing a portion of the Si contained in the crystal structure of the first fluoride particles with Al, the F deficiency in the crystal structure of the fluoride phosphor is compensated, the crystal structure is stabilized, and the brightness is improved.

[0059] First preparation process

[0060] In the first preparation step, first fluoride particles having a second composition are prepared. In the second composition, relative to the total molar number of alkali metals, the ratio of the total molar number of Si and Mn is 0.9 or more and 1.1 or less, the ratio of the molar number of Mn is greater than 0 and 0.2 or less, and the ratio of the molar number of F can be 5.9 or more and 6.1 or less, or 5.5 or more and less than 6.0. The ratio of the total molar number of Si and Mn is preferably 0.95 or more and 1.05 or less, or 0.97 or more and 1.03 or less. Furthermore, the ratio of the molar number of Mn is preferably 0.005 or more and 0.15 or less, 0.01 or more and 0.12 or less, or 0.015 or more and 0.1 or less. Additionally, the ratio of the molar number of F is preferably 5.95 or more and 6.05 or less, or 5.97 or more and 6.03 or less, or 5.9 or more and less than 6.0, 5.96 or more and 5.995 or less, or 5.97 or more and 5.99 or less.

[0061] The first fluoride particle may have a composition represented by the following formula (III) as the second composition.

[0062] M2[Si b Mn c F d (III)

[0063] In formula (III), M can represent an alkali metal and at least contain K. Mn can be a tetravalent Mn ion. b, c, and d can satisfy 0.9≤b+c≤1.1, 0<c≤0.2, 5.9≤d≤6.1, or 5.5≤d<6.0. Preferably, they can be 0.95≤b+c≤1.05 or 0.97≤b+c≤1.03, 0.005≤c≤0.15, 0.01≤c≤0.12 or 0.015≤c≤0.1, 5.95≤d≤6.05 or 5.97≤d≤6.03 or 5.9≤d<6.0, 5.96≤d≤5.995 or 5.97≤d≤5.99.

[0064] In addition, the first fluoride particle may have a second theoretical composition represented by the following formula (IIIa).

[0065] M2SiF6:Mn(IIIa)

[0066] In formula (IIIa), M can represent an alkali metal and includes at least K. Mn can be a tetravalent Mn ion.

[0067] For the median particle size of the first fluoride particles in terms of volume, for example, from the viewpoint of improving brightness, it can be 10 μm or more and 90 μm or less, preferably 15 μm or more and 70 μm or less, or 20 μm or more and 50 μm or less. For example, from the viewpoint of improving brightness, the particle size distribution of the first fluoride particles can show a particle size distribution with a single peak, preferably a particle size distribution with a single peak with a narrow distribution width. Specifically, in the particle size distribution in terms of volume, when the particle size corresponding to 10% of the volume accumulation from the small diameter side is set as D10 and the particle size corresponding to 90% of the volume accumulation is set as D90, the ratio of D90 to D10 (D90 / D10) can be 3.0 or less.

[0068] The first fluoride particle can be, for example, a phosphor activated with tetravalent Mn ions, which absorbs light in the short wavelength region of the visible spectrum and emits red light. The excitation light can be mainly blue light, and the peak wavelength of the excitation light can be, for example, in the wavelength range of 380 nm to 485 nm. The peak wavelength of the emission spectrum of the first fluoride particle can be, for example, in the wavelength range of 610 nm to 650 nm. The half-width at half-maximum (WWHM) of the emission spectrum of the first fluoride particle can be, for example, less than 10 nm.

[0069] First fluoride particles can be prepared by purchase or by manufacturing using the methods described below. The manufacturing method is described below when the alkali metal is potassium; however, the same method can be used when the alkali metal includes other alkali metals besides potassium.

[0070] A method for manufacturing first fluoride particles includes, for example, a step of mixing a first solution containing at least potassium ions and hydrogen fluoride, a second solution containing at least a first complex ion containing tetravalent manganese ions and hydrogen fluoride, and a third solution containing at least a second complex ion containing silicon and fluoride ions. By mixing the first, second, and third solutions, first fluoride particles with a desired composition and functioning as phosphors can be manufactured using a simple and highly productive method.

[0071] The first solution contains at least potassium ions and hydrogen fluoride, and may contain other components as needed. For example, the first solution may be obtained as an aqueous solution of hydrofluoric acid containing a compound with potassium ions. Examples of compounds containing potassium ions constituting the first solution include water-soluble compounds such as halides, hydrofluorides, hydroxides, acetates, and carbonates containing potassium ions. Specifically, examples include water-soluble potassium salts such as KF, KHF2, KOH, KCl, KBr, KI, CH3COOK, and K2CO3. Among these, KHF2 is preferred from the perspective of dissolving without reducing the concentration of hydrogen fluoride in the solution, having low heat of solution, and high safety. One compound containing potassium ions constituting the first solution may be used alone, or two or more compounds may be used in combination.

[0072] The lower limit of the hydrogen fluoride concentration in the first solution is typically 1% by mass or more, preferably 3% by mass or more, and more preferably 5% by mass or more. The upper limit of the hydrogen fluoride concentration in the first solution is typically 80% by mass or less, preferably 75% by mass or less, and more preferably 70% by mass or less. The lower limit of the potassium ion concentration in the first solution is typically 1% by mass or more, preferably 3% by mass or more, and more preferably 5% by mass or more. The upper limit of the potassium ion concentration in the first solution is typically 30% by mass or less, preferably 25% by mass or less, and more preferably 20% by mass or less. When the potassium ion concentration is 5% by mass or more, there is a tendency for an increased yield of the first fluoride particles.

[0073] The second solution contains at least a first complex ion containing tetravalent Mn ions and hydrogen fluoride, and may contain other components as needed. The second solution can be obtained, for example, as an aqueous solution of hydrofluoric acid containing a tetravalent manganese source. The manganese source is, for example, a compound containing tetravalent Mn ions. Specific examples of manganese sources constituting the second solution include K₂MnF₆, KMnO₄, and K₂MnCl₆. Among these, K₂MnF₆ is preferred from the perspective of not containing chlorine, which tends to cause instability due to lattice deformation, maintaining an active oxidation number (tetravalent), and being stable in hydrofluoric acid as a MnF₆ complex ion. It should be noted that, among the manganese sources, a manganese source containing potassium ions can also serve as the potassium ion source contained in the first solution. One type of manganese source constituting the second solution may be used alone, or two or more types may be used in combination.

[0074] The lower limit of the hydrogen fluoride concentration in the second solution is typically 1% by mass or more, preferably 3% by mass or more, and more preferably 5% by mass or more. Furthermore, the upper limit of the hydrogen fluoride concentration in the second solution is typically 80% by mass or less, preferably 75% by mass or less, and more preferably 70% by mass or less. The lower limit of the first complex ion concentration in the second solution is typically 0.01% by mass or more, preferably 0.03% by mass or more, and more preferably 0.05% by mass or more. Furthermore, the upper limit of the first complex ion concentration in the second solution is typically 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less.

[0075] The third solution contains at least a second complex ion containing silicon and fluoride ions, and may contain other components as needed. The third solution can be obtained, for example, as an aqueous solution containing a second complex ion source. The second complex ion source is preferably a compound containing silicon and fluoride ions and exhibiting excellent solubility in solution. Specific examples of second complex ion sources include: H₂SiF₆, Na₂SiF₆, (NH₄)₂SiF₆, Rb₂SiF₆, Cs₂SiF₆, etc. Among these, H₂SiF₆ is preferred due to its high solubility in water and the absence of alkali metal elements as impurities. One type of second complex ion source constituting the third solution may be used alone, or two or more may be used in combination.

[0076] The lower limit of the concentration of the second complex ion in the third solution is typically 10% by mass or more, preferably 15% by mass or more, and more preferably 20% by mass or more. Furthermore, the upper limit of the concentration of the second complex ion in the third solution is typically 60% by mass or less, preferably 55% by mass or less, and more preferably 50% by mass or less.

[0077] As a method for mixing the first, second, and third solutions, for example, the second and third solutions can be added and mixed while stirring the first solution, or the first and second solutions can be added and mixed while stirring the third solution. Alternatively, the first, second, and third solutions can be added to containers separately and stirred and mixed.

[0078] By mixing the first, second, and third solutions, the first complex ion, potassium ion, and second complex ion react to precipitate crystals of the target first fluoride particles. The precipitated crystals can be recovered through solid-liquid separation such as filtration. Alternatively, a reducing agent such as hydrogen peroxide water can be added, and the crystals can be washed with solvents such as ethanol, isopropanol, water, or acetone. Furthermore, a drying process can be performed. The drying process is typically carried out at 50°C or higher, preferably 55°C or higher, more preferably 60°C or higher, and typically below 110°C, preferably below 105°C, more preferably below 100°C. The drying time is not particularly limited, as long as the moisture adhering to the first fluoride particles is removed; for example, it is about 10 hours.

[0079] It should be noted that, when mixing the first solution, the second solution, and the third solution, considering the deviation between the composition of the phosphor raw material and the composition of the obtained first fluoride particles, it is preferable to appropriately adjust the mixing ratio of the first solution, the second solution, and the third solution so that the composition of the first fluoride particles as the product becomes the target composition.

[0080] The method for manufacturing first fluoride particles may include a granulation process that combines drying treatment with crushing, pulverizing, and grading operations. Powder with a desired particle size can be obtained through the granulation process.

[0081] Second preparation process

[0082] In the second preparation step, second fluoride particles having a third composition are prepared. In the third composition, the proportion of the total moles of alkali metal relative to the number of moles of Al is 1 or more and 3 or less, and the proportion of the number of moles of F is 4 or more and 6 or less. In one embodiment, in the third composition, the proportion of the total moles of alkali metal relative to the number of moles of Al is 2 or more and 3 or less, and the proportion of the number of moles of F is 5 or more and 6 or less.

[0083] The second fluoride particle may have a composition represented by the following formula (IV) as the third component.

[0084] M e [AlF f (IV)

[0085] In equation (IV), M can represent an alkali metal and includes at least K. e and f can satisfy 2≤e≤3 and 5≤f≤6.

[0086] The second fluoride particle may have a composition represented by the following formula (IVa) or (IVb), or may contain both compositions.

[0087] M3[AlF6] (IVa)

[0088] M2[AlF5] (IVb)

[0089] The specific surface area of ​​the second fluoride particle, for example, considering its reactivity with the first fluoride particle, can be 0.3 m². 2 ·g -1 The above, preferably, can be 1m 2 ·g -1 or above 3m 2 ·g -1 The above. The upper limit of the specific surface area of ​​the second fluoride particles can be, for example, 30 m². 2 ·g -1 Specific surface area can be determined, for example, by the BET method.

[0090] Secondary fluoride particles can be prepared by purchase or by manufacturing using known methods.

[0091] First heat treatment process

[0092] The first heat treatment step may include: mixing prepared first fluoride particles and second fluoride particles to obtain a mixture; and subjecting the obtained mixture to a first heat treatment in an inert gas atmosphere at a temperature range of 600°C to 780°C to obtain a first heat-treated product. The first heat-treated product contains a fluoride phosphor as a target.

[0093] The first fluoride particles and the second fluoride particles can be mixed, for example, by a conventional dry mixing process. Dry mixing can be carried out, for example, using a high-speed flow mixer. Regarding the ratio of the first fluoride particles to the second fluoride particles in the mixture, the ratio of the number of moles of the second fluoride particles to the total number of moles of the first and second fluoride particles can, for example, be greater than 0 and less than 0.1. Preferably, it can be less than 0.05 or less than 0.03 moles. The lower limit of the molar ratio of the second fluoride particles is preferably 0.003 or more or 0.005 or more.

[0094] The heat treatment temperature in the first heat treatment step (hereinafter also referred to as the first heat treatment temperature) can be, for example, 600°C or higher. Preferably, the heat treatment temperature can be 625°C or higher, 650°C or higher, or 675°C or higher. When the heat treatment temperature is 600°C or higher, the first fluoride particles can be efficiently introduced into the second fluoride particles, allowing a portion of the Si in the crystal structure of the first fluoride particles to be replaced by Al, resulting in a high-brightness fluoride phosphor. Alternatively, the heat treatment temperature in the first heat treatment step can be, for example, lower than 800°C. Preferably, the heat treatment temperature can be 780°C or lower, 770°C or lower, 760°C or lower, or 750°C or lower. When the heat treatment temperature is lower than 800°C, the thermal decomposition of the fluoride phosphor can be effectively suppressed. In one embodiment, the first heat treatment temperature in the first heat treatment can be 650°C or higher and 750°C or lower.

[0095] The heat treatment time in the first heat treatment step can be, for example, 1 hour or more and 40 hours or less, preferably 2 hours or more and 30 hours or less. When the heat treatment time is within the above range, the substitution of Si into Al in the crystal structure of the first fluoride particles proceeds more efficiently, tending to yield fluoride phosphors with high brightness. Here, the heat treatment time in the first heat treatment step refers to the time during which the mixture of the first fluoride particles and the second fluoride particles is held at the first heat treatment temperature. The heating rate up to the first heat treatment temperature in the first heat treatment step can be, for example, 1°C / minute or more.

[0096] In the first heat treatment step, the heat treatment of the mixture can be carried out in an inert gas atmosphere. An inert gas atmosphere refers to a gas atmosphere whose main components are, for example, rare gases such as argon and helium, or inert gases such as nitrogen. The main component in the inert gas atmosphere need only be selected from at least one of argon, helium, and nitrogen, and may contain at least nitrogen. The concentration of the inert gas in the inert gas atmosphere, such as nitrogen, may be, for example, 70% by volume or more, preferably 80% by volume or more, 85% by volume or more, 90% by volume or more, or 95% by volume or more. The inert gas may sometimes contain reactive gases such as oxygen as unavoidable impurities. The concentration of reactive gases in the gas atmosphere in the first heat treatment step need only be 15% by volume or less, preferably less than 5% by volume, less than 1% by volume, less than 0.3% by volume, or less than 0.1% by volume. The inert gas atmosphere may not contain reactive gases such as oxygen. When the concentration of reactive gases in the inert gas atmosphere is within the above range, the oxidation of tetravalent Mn contained in the mixture can be sufficiently suppressed.

[0097] The pressure during heat treatment in the first heat treatment process can be, for example, atmospheric pressure (0.101 MPa). The pressure during heat treatment can be greater than 0.101 MPa and less than 1 MPa, or it can be a reduced pressure lower than atmospheric pressure (0.101 MPa).

[0098] Cleaning process

[0099] The method for manufacturing the luminescent material may further include a cleaning step in which the first heat-treated material obtained in the first heat treatment step is brought into contact with a first liquid medium. The cleaning step may, for example, include: bringing the first heat-treated material into contact with the first liquid medium; and performing solid-liquid separation on the first heat-treated material after contact with the first liquid medium, and may further include drying the first heat-treated material after solid-liquid separation, as needed.

[0100] By contacting the first heat-treated material with a first liquid medium, at least a portion of the impurities (e.g., alkali metal fluorides such as potassium fluoride) generated in the first heat treatment step can be removed. It can be considered that this can suppress compositional changes in the resulting fluoride phosphor, effectively suppressing the decrease in brightness caused by compositional changes.

[0101] Examples of first liquid media that come into contact with the first heat-treated material include: lower alcohols such as ethanol and isopropanol, ketone solvents such as acetone, and water. From the viewpoint of removing impurities, the first liquid medium may contain at least water, which may be deionized water, distilled water, or purified water purified using a precision filtration membrane, ultrafiltration membrane, or reverse osmosis membrane.

[0102] The first liquid medium may contain a reducing agent such as hydrogen peroxide. By including a reducing agent in the first liquid medium, even if the tetravalent Mn ions, which act as activators in the fluoride phosphor, are oxidized by the first heat treatment, they can be reduced by the reducing agent in the first liquid medium, thereby further improving the luminescence properties of the obtained fluoride phosphor. When the first liquid medium contains a reducing agent, its content can be, for example, 0.01% by mass or more and 5% by mass or less, preferably 0.05% by mass or more and 1% by mass or less. The amount of the first liquid medium used for contact with the first heat-treated object can be, for example, 2 times or more and 20 times or less relative to the total mass of the first heat-treated object.

[0103] Contact between the first heat-treated material and the first liquid medium can be implemented by removing the first liquid medium after mixing the first heat-treated material and the first liquid medium, or by having the first liquid medium pass through the first heat-treated material held in a funnel or the like. The contact time between the first heat-treated material and the first liquid medium can be, for example, 1 hour or more and 20 hours or less. Furthermore, the contact temperature between the first heat-treated material and the first liquid medium can be, for example, 10°C or more and 50°C or less.

[0104] A drying process can be performed on the first heat-treated object that comes into contact with the first liquid medium. The drying temperature during the drying process can be, for example, 50°C or higher, preferably 55°C or higher or 60°C or higher, and for example, 110°C or lower, preferably 105°C or lower or 100°C or lower. The drying time is the time required for at least a portion of the first liquid medium (e.g., moisture) that has adhered to the first heat-treated object through contact with the first liquid medium to evaporate, for example, about 10 hours.

[0105] Second heat treatment process

[0106] The method for manufacturing the luminescent material may further include a second heat treatment step: subjecting a first heat-treated material that has been in contact with a first liquid medium to a second heat treatment temperature of 400°C or higher to obtain a second heat-treated material. The second heat-treated material contains a fluoride phosphor as a target. Alternatively, the method for manufacturing the luminescent material may further include a second heat treatment step: subjecting a first heat-treated material that has not been in contact with a liquid medium to a second heat treatment temperature of 400°C or higher to obtain a second heat-treated material.

[0107] Regarding the effect of the second heat treatment process, the following can be considered, for example. It can be assumed that in the fluoride phosphor with the first composition synthesized by the first heat treatment and solid-state reaction method, silicon ions (e.g., Si) are mixed at the same atomic coordinate in the crystallization. 4+ ), aluminum ions (e.g., Al) 3+ ) and manganese ions (e.g., Mn) 4+ The atomic coordinates of the fluoride ions in the crystal are in a state of mixed valence. It can be considered that, to compensate for the lack of charge in the cations with mixed valence, vacancies exist in the atomic coordinates of the fluoride ions in the crystal, corresponding to the ratio of the presence of each ion. On the other hand, it can be considered that, in fluoride particles with a third composition synthesized by liquid-phase reaction, the atomic coordinates of the fluoride ions in the crystal contain multiple hydroxide ions introduced into the crystal by hydroxide ions present in the reaction solution, which become a cause of impaired phosphor stability. In contrast, it can be considered that, in fluoride phosphors with a first composition synthesized by first heat treatment and solid-phase reaction, there are no hydroxide ions mixed in that cause impaired phosphor stability. Furthermore, in fluoride phosphors with a first composition synthesized by first heat treatment and solid-phase reaction, manganese ions with different valences are sometimes mixed in the crystal or on the surface of the crystal. It can be assumed that even when manganese ions with different valences are mixed in the phosphor, the valences of the manganese ions can be made uniformly tetravalent by performing a second heat treatment, thereby improving the extraction efficiency of fluorescence emitted from the fluoride phosphor.

[0108] The second heat treatment can be performed by holding the first heat-treated object at a second heat treatment temperature for a given time. The second heat treatment temperature can be, for example, 400°C or higher, preferably above 400°C, 425°C or higher, 450°C or higher, or 480°C or higher. The upper limit of the second heat treatment temperature can be, for example, below 600°C, preferably below 580°C, 550°C or lower, or 520°C. The second heat treatment temperature can be lower than the first heat treatment temperature.

[0109] When the second heat treatment temperature is above the aforementioned lower limit, the manganese ions contained in the first heat-treated material can be made to be uniformly in a tetravalent state, and there is a tendency to further improve the brightness of the obtained luminescent material containing fluoride phosphors. Furthermore, when the second heat treatment temperature is below the aforementioned upper limit, the decomposition of the obtained luminescent material containing fluoride phosphors can be more effectively suppressed, and there is a tendency to further improve the brightness of the obtained luminescent material containing fluoride phosphors.

[0110] The heat treatment time in the second heat treatment, i.e., the time for maintaining the second heat treatment temperature, can be, for example, more than 1 hour and less than 40 hours, preferably more than 2 hours or more than 3 hours, and more preferably less than 30 hours, less than 10 hours, or less than 8 hours. When the heat treatment time at the second heat treatment temperature is within the above range, the manganese ions contained in the first heat-treated material can be made sufficiently uniformly in a tetravalent state. As a result, the crystal structure of the luminescent material containing the fluoride phosphor becomes more stable, and there is a tendency to obtain a luminescent material containing the fluoride phosphor with high brightness.

[0111] The heat treatment time at the second heat treatment temperature can be the same as or longer than the heat treatment time at the first heat treatment temperature. That is, the heat treatment time at the second heat treatment temperature can be more than twice the heat treatment time at the first heat treatment temperature. This allows the manganese ions in the first heat-treated material to be uniformly in a tetravalent state, potentially further increasing the brightness of the resulting luminescent material containing fluoride phosphors.

[0112] The pressure in the second heat treatment process can be atmospheric pressure (0.101 MPa), can exceed atmospheric pressure but be less than 5 MPa, or can exceed atmospheric pressure but be less than 1 MPa.

[0113] In the second heat treatment step, the second heat treatment can be performed while the first heat-treated product is in contact with the fluorine-containing substance. The fluorine-containing substance used in the second heat treatment step can be in any state at room temperature, including solid, liquid, or gaseous states. Examples of solid or liquid fluorine-containing substances include NH4F. Examples of gaseous fluorine-containing substances include F2, CHF3, CF4, NH4HF2, HF, SiF4, KrF4, XeF2, XeF4, and NF3, and at least one of these can be selected, preferably at least one selected from F2 and HF.

[0114] When the fluorine-containing substance is in a solid or liquid state at room temperature, it can be brought into a state of contact by mixing the first heat-treated material after contact with the liquid medium. For example, the first heat-treated material can be mixed with a fluorine-containing substance of 1% to 20% to 10% by mass (preferably 2% to 10% by mass) relative to the total mass of the first heat-treated material and the fluorine-containing substance.

[0115] The temperature at which the first heat-treated material and the fluorine-containing substance are mixed can be, for example, from room temperature (20°C ± 5°C) to a temperature lower than the second heat-treatment temperature, or it can be the second heat-treatment temperature. Specifically, it can be a temperature above 20°C and below 400°C, or it can be a temperature above 400°C. When the temperature at which the first heat-treated material comes into contact with the fluorine-containing substance, which is in a solid or liquid state at room temperature, is above 20°C and below 400°C, the second heat treatment is performed at a temperature above 400°C after the first heat-treated material comes into contact with the fluorine-containing substance.

[0116] When the fluorine-containing substance is a gas, the first heat-treated material can be placed in and brought into contact with the gaseous atmosphere containing the fluorine-containing substance. In addition to the fluorine-containing substance, the gaseous atmosphere may also contain rare gases, nitrogen, or other inert gases. In this case, the concentration of the fluorine-containing substance in the gaseous atmosphere can be, for example, 3% by volume or more and 35% by volume or less, preferably 5% by volume or more or 10% by volume or more, and more preferably 30% by volume or less or 25% by volume or less.

[0117] The manufacturing method of luminescent materials may include a granulation process after the second heat treatment step, which involves crushing, pulverizing, and classifying the resulting mixture of materials from the second heat treatment. Powder with the desired particle size can be obtained through this granulation process.

[0118] In one embodiment, the method for manufacturing the luminescent material may further include a pressure heating step of pressurizing and heating a mixture comprising a first heat-treated material and a second liquid medium to obtain a third heat-treated material. By pressurizing and heating the first heat-treated material together with the second liquid medium, there is a tendency to further increase the brightness of the resulting luminescent material containing a fluoride phosphor. Here, the first heat-treated material supplied for the pressure heating step may be the first heat-treated material after the aforementioned cleaning step based on the first liquid medium.

[0119] Examples of second liquid media include: lower alcohols such as ethanol and isopropanol, ketone solvents such as acetone, and water. From the viewpoint of removing impurities, the second liquid media may contain at least water, which may be deionized water, distilled water, or purified water purified using a precision filtration membrane, ultrafiltration membrane, or reverse osmosis membrane. Furthermore, the second liquid media may be a substance that can be liquefied by pressure even when it is a gas at normal pressure, or a substance that can be liquefied by heating even when it is a solid at room temperature. One type of second liquid media may be used alone, or two or more may be used in combination. The amount of the second liquid media used for pressurized heat treatment, as a mass ratio relative to the total mass of the first heat-treated material, may be, for example, 0.5 or more and 2 or less, preferably 0.7 or more and 1.6 or less.

[0120] The second liquid medium may further contain components soluble in it. Examples of components soluble in the second liquid medium include: inorganic acids such as hydrogen fluoride (HF), hexafluorosilicic acid (H₂SiF₆), and nitric acid (HNO₃); peroxides such as hydrogen peroxide; and inorganic acid salts containing potassium ions such as potassium hydrogen fluoride (KHF₂), potassium nitrate (KNO₃), and potassium fluoride (KF). The second liquid medium may contain at least potassium ions, or at least inorganic acid salts containing potassium ions. When the second liquid medium contains potassium ions, the concentration of potassium ions may be, for example, 5% by mass or more and 10% by mass or less. The components soluble in the second liquid medium may be used alone or in combination of two or more.

[0121] From the viewpoint of improving the durability of the luminescent material, the pressure applied during the pressurization process can be calculated to be, for example, 1.5 MPa or more, preferably 2.5 MPa or more, or 5.0 MPa or more. From the viewpoint of durability and manufacturing efficiency, the upper limit of the pressure can be, for example, 30 MPa or less, preferably 15 MPa or less.

[0122] The pressure treatment time can be appropriately selected based on the pressure and other treatment conditions. From the perspective of improving durability, the treatment time can be, for example, 4 hours or more, preferably 6 hours or more, or 8 hours or more. From the perspective of durability and manufacturing efficiency, the upper limit of the treatment time can be, for example, 48 hours or less, preferably 24 hours or less, or 20 hours or less.

[0123] Pressurization can be achieved by placing the mixture into a pressure-resistant, sealed container such as an autoclave and pressurizing it. The pressurization method can be appropriately selected from commonly used methods. Specifically, pressurization can be achieved by reducing the volume of the pressure-resistant, sealed container, by introducing gases such as air or inert gases, or by heating the mixture while maintaining a sealed state, utilizing the vapor pressure of a liquid medium. The gas atmosphere used for pressurization can be atmospheric or an inert gas atmosphere.

[0124] From the viewpoint of improving durability, the heat treatment temperature can be, for example, 100°C or higher, preferably 120°C or higher, or 150°C or higher. From the viewpoint of durability and manufacturing efficiency, the upper limit of the heat treatment temperature can be, for example, 300°C or lower, preferably 200°C or lower.

[0125] The heat treatment time can be appropriately selected based on processing conditions such as temperature. From the viewpoint of improving durability, the heat treatment time can be, for example, 4 hours or more, preferably 8 hours or more. From the viewpoint of durability and manufacturing efficiency, the upper limit of the heat treatment time can be, for example, 24 hours or less, preferably 20 hours or less. The gas atmosphere for heat treatment can be an atmospheric atmosphere or an inactive gas atmosphere.

[0126] In the manufacturing method of luminescent materials, when pressure and heat treatments are performed, the pressure and heat treatments can be performed sequentially or overlappingly in time. When the pressure and heat treatments are performed overlappingly in time, for example, the mixture can be placed in a pressure-resistant sealed container and heated, thereby utilizing the vapor pressure of the liquid medium for pressure treatment.

[0127] In the manufacturing method of luminescent materials, the first heat-treated material and the second liquid medium can be subjected to pressurized heating treatment for 8 hours to 48 hours at a temperature of 120°C or higher and 300°C or lower and a pressure of 2.5 MPa or higher and 30 MPa or lower. It is preferable to perform pressurized heating treatment for 6 hours to 24 hours at a temperature of 150°C or higher and 200°C and a pressure of 5.0 MPa or higher and 12 MPa or lower.

[0128] In addition to pressure treatment and heat treatment, the manufacturing method of luminescent materials can further include post-processing steps such as separation, purification, and drying of the heat-treated material, and may include a granulation process that combines crushing, pulverizing, and grading operations. Powder with the desired particle size can be obtained through the granulation process.

[0129] The details of the fluoride phosphor contained in the luminescent material obtained by the manufacturing method of the luminescent material are the same as those of the fluoride phosphor described above. That is, the fluoride phosphor contained in the obtained luminescent material may have a composition represented by the following formula (I).

[0130] M2[Si p Al q Mn r F s (I)

[0131] In equation (I), M can represent an alkali metal and includes at least K. p, q, r and s satisfy 0.9≤p+q+r≤1.1, 0<q<0.1, 0<r<0.2, 5.9≤s≤6.1 or 5.5≤s≤6.0.

[0132] The method for manufacturing the luminescent material may further include: a synthesis step in which an oxide from the metal alkoxide is disposed on at least a portion of the surface of the fluoride phosphor contained in the first, second, or third heat-treated product obtained by the above-described manufacturing method, in a liquid medium. In this synthesis step, the oxide is contacted with a metal alkoxide comprising at least one selected from Si, Al, Ti, Zr, Sn, and Zn. In the synthesis step, the amount of oxide disposed relative to the luminescent material may be 2% by mass or more and 30% by mass or less.

[0133] By contacting the fluoride phosphor contained in the first, second, or third heat-treated material with a metal alkoxide in a liquid medium, a luminescent material in which at least a portion of the surface of the fluoride phosphor is disposed with an oxide from the metal alkoxide can be efficiently manufactured. For light-emitting devices comprising a fluorescent component including the obtained luminescent material and a resin, reliability is improved, for example, at high-temperature environments.

[0134] In the synthesis process, oxides from metal alkoxides can be generated by solvation of metal alkoxides, and a luminescent material in which at least a portion of the surface of the fluoride phosphor contained in the second heat-treated material is configured with the generated oxides can be obtained.

[0135] The aliphatic group of the alkoxide constituting the metal alkoxide may have 1 or more and 6 or less carbon atoms, preferably 1 or more and 4 or less, or 1 or more and 3 or less. The metal alkoxide contains at least one of the following: Si, Al, Ti, Zr, Sn, and Zn, or may contain at least Si. The metal and aliphatic group contained in the metal alkoxide may each contain only one type, or may contain two or more types in combination.

[0136] Specific examples of metal alkoxides include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, aluminum triethanolamine, aluminum triethanolamine, aluminum triisopropoxide, titanium tetraethanolamine, titanium tetraethanolamine, titanium tetraisopropoxide, zirconium tetraethanolamine, zirconium tetraethanolamine, zirconium tetraisopropoxide, tin tetraethanolamine, zinc diethanolamine, and zinc diethanolamine, preferably selected from at least one of these, more preferably selected from at least one of tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane. The metal alkoxide used in the synthesis process can be a single type or a combination of two or more types.

[0137] Relative to the total mass of the first, second, or third heat-treated product, the amount of metal alkoxide added in the synthesis step, calculated as the amount added in oxide form, can be, for example, 2% by mass or more and 30% by mass or less, preferably 5% by mass or more or 8% by mass or more, and preferably 25% by mass or less or 20% by mass or less. Furthermore, relative to the total mass of the first, second, or third heat-treated product, the amount of metal alkoxide added in the synthesis step, calculated as the amount of metal alkoxide added, can be, for example, 5% by mass or more and 110% by mass or less, preferably 15% by mass or more or 25% by mass or more, and preferably 90% by mass or less or 75% by mass or less.

[0138] The contact between the first, second, or third heat-treated product and the metal alkoxide is carried out in a liquid medium. Examples of liquid media include: water; alcohol solvents such as methanol, ethanol, and isopropanol; nitrile solvents such as acetonitrile; and hydrocarbon solvents such as hexane. The liquid medium may contain at least water and an alcohol solvent. When the liquid medium contains an alcohol solvent, the alcohol solvent content in the liquid medium may be, for example, 60% by mass or more, preferably 70% by mass or more. Furthermore, the water content in the liquid medium may be, for example, 4% by mass or more and 40% by mass or less.

[0139] Furthermore, the liquid medium may further contain a pH adjuster. Examples of pH adjusters include alkaline substances such as ammonia, sodium hydroxide, and potassium hydroxide, and acidic substances such as hydrochloric acid, nitric acid, sulfuric acid, and acetic acid. When the liquid medium contains a pH adjuster, the pH of the liquid medium can be, for example, 1 or higher and 6 or lower under acidic conditions, preferably 2 or higher and 5 or lower. Under alkaline conditions, it can be 8 or higher and 12 or lower, preferably 8 or higher and 11 or lower.

[0140] The mass ratio of the liquid medium relative to the first, second, or third heat-treated product can be, for example, 100% by mass or more and 1000% by mass or less, preferably 150% by mass or more or 180% by mass or more, and preferably 600% by mass or less or 300% by mass or less. When the mass ratio of the liquid medium is within the above range, there is a tendency to more uniformly cover the fluoride phosphor with oxides.

[0141] The contact between the first, second, or third heat-treated product and the metal alkoxide can be achieved, for example, by adding the metal alkoxide to a suspension containing the first, second, or third heat-treated product. At this time, stirring or the like can be performed as needed. Furthermore, the contact temperature between the first, second, or third heat-treated product and the metal alkoxide can be, for example, 0°C or higher and 70°C or lower, preferably 10°C or higher and 40°C or lower. The contact time can be, for example, 1 hour or more and 12 hours or less. It should be noted that the contact time also includes the time required for the addition of the metal alkoxide.

[0142] The manufacturing method of luminescent materials may further include: a process of recovering the luminescent materials obtained through the synthesis process by solid-liquid separation after the synthesis process; and a process of drying the luminescent materials obtained by solid-liquid separation.

[0143] The method for manufacturing luminescent materials may further include: contacting a first heat-treated material, a second heat-treated material, or a third heat-treated material obtained by the above manufacturing method, a rare earth ion containing at least one lanthanide element selected from La, Ce, Dy, and Gd, and phosphate ions in a liquid medium to obtain an attachment step in which at least a portion of the surface of the fluoride phosphor contained in the first heat-treated material, the second heat-treated material, or the third heat-treated material is coated with a fluoride phosphor containing rare earth phosphate.

[0144] By contacting the fluoride phosphor, rare earth ions, and phosphate ions contained in the first, second, or third heat-treated material in a liquid medium, a luminescent material with at least a portion of the surface of the fluoride phosphor coated with rare earth phosphates can be efficiently manufactured. Luminescent materials with rare earth phosphates coated on the surface of the fluoride phosphor tend to exhibit further improved resistance to damp heat.

[0145] In the attachment process, the fluoride phosphor, rare earth ions, and phosphate ions contained in the first, second, or third heat-treated material are brought into contact in a liquid medium. As a result, rare earth phosphates adhere to the surface of the fluoride phosphor, yielding a fluoride phosphor with attached rare earth phosphates. It can be considered that by attaching rare earth phosphates to the fluoride phosphor in a liquid medium, the rare earth phosphates can be more uniformly attached to, for example, the surface of the fluoride phosphor.

[0146] The liquid medium only needs to be able to dissolve phosphate ions and rare earth ions; considering the ease with which these ions dissolve, it is preferable to contain at least water. The liquid medium may further contain reducing agents such as hydrogen peroxide, organic solvents, pH adjusters, etc., as needed. Examples of organic solvents that can be included in the liquid medium include alcohols such as ethanol and isopropanol. Examples of pH adjusters include alkaline compounds such as ammonia, sodium hydroxide, and potassium hydroxide; and acidic compounds such as hydrochloric acid, nitric acid, sulfuric acid, and acetic acid. When the liquid medium contains a pH adjuster, the pH of the liquid medium is, for example, 1 to 6, preferably 1.5 to 4. When the pH is above the lower limit, there is a tendency to obtain a sufficient amount of rare earth phosphate adsorption; conversely, when the pH is below the upper limit, there is a tendency to suppress the reduction of the luminescence properties of the fluoride phosphor. When the liquid medium contains water, the water content in the liquid medium is, for example, 70% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more.

[0147] The mass ratio of the liquid medium relative to the first, second, or third heat-treated product is, for example, 100% by mass or more, or 200% by mass or more, and also, for example, 1000% by mass or less, or 800% by mass or less. When the mass ratio of the liquid medium is above the aforementioned lower limit, it is easier for rare earth phosphates to adhere more uniformly to the surface of the fluoride phosphor; when the mass ratio of the liquid medium is below the aforementioned upper limit, there is a tendency for the adhesion rate of rare earth phosphates to the fluoride phosphor to further increase.

[0148] The liquid medium preferably contains phosphate ions, more preferably water and phosphate ions. When the liquid medium contains phosphate ions, the phosphate ions can be brought into contact with the rare earth ions in the liquid medium by mixing the first, second, or third heat-treated material with the liquid medium and further mixing it with a solution containing rare earth ions. When the liquid medium contains phosphate ions, the concentration of phosphate ions in the liquid medium is, for example, 0.05% by mass or more, preferably 0.1% by mass or more, and also, for example, 5% by mass or less, preferably 3% by mass or less. When the concentration of phosphate ions in the liquid medium is above the aforementioned lower limit, the amount of liquid medium will not become excessive, and the leaching of components from the second or third heat-treated material can be suppressed, tending to maintain the properties of the fluoride phosphor contained in the first, second, or third heat-treated material well. Furthermore, when the concentration is below the aforementioned upper limit, there is a tendency for the uniformity of the adhesion to the first, second, or third heat-treated material to become better.

[0149] Phosphate ions include orthophosphate ions, polyphosphoric acid (metaphosphate) ions, phosphite ions, and hypophosphite ions. Polyphosphoric acid ions include linear polyphosphoric acid ions such as pyrophosphate ions and tripolyphosphate ions, and cyclic polyphosphoric acid ions such as hexametaphosphate ions.

[0150] When the liquid medium contains phosphate ions, the phosphate ion source can be prepared by dissolving the compound in the liquid medium, or by mixing the solution containing the phosphate ion source with the liquid medium. Examples of phosphate ion sources include: phosphoric acid; metaphosphoric acid; alkali metal phosphates such as sodium phosphate and potassium phosphate; alkali metal hydrogen phosphates such as sodium hydrogen phosphate and potassium hydrogen phosphate; alkali metal dihydrogen phosphates such as sodium dihydrogen phosphate and potassium dihydrogen phosphate; alkali metal hexametaphosphates such as sodium hexametaphosphate and potassium hexametaphosphate; alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate; and ammonium phosphates such as ammonium phosphate.

[0151] The liquid medium preferably contains a reducing agent, more preferably water and a reducing agent, and even more preferably water, phosphate ions, and a reducing agent. By including a reducing agent in the liquid medium, the precipitation of manganese dioxide and other substances from manganese contained in the first, second, or third heat-treated product can be effectively suppressed. The reducing agent contained in the liquid medium can reduce, for example, tetravalent manganese ions dissolved from the first, second, or third heat-treated product into the liquid medium; examples include hydrogen peroxide, oxalic acid, and hydroxylamine hydrochloride. Hydrogen peroxide decomposes in water, therefore, it is preferred from the viewpoint that it will not adversely affect the fluoride phosphor contained in the first, second, or third heat-treated product.

[0152] When the liquid medium contains a reducing agent, it can be prepared by dissolving the compound that will become the reducing agent in the liquid medium, or by mixing a solution containing the reducing agent with the liquid medium. There is no particular limitation on the content of the reducing agent in the liquid medium, but for the reasons mentioned above, it is, for example, 0.1% by mass or more, preferably 0.3% by mass or more.

[0153] Rare earth elements that can become rare earth ions in contact with phosphate ions include, in addition to Sc and Y, lanthanide elements including La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Preferably, at least one of the lanthanide elements is selected, and more preferably, at least one of La, Ce, Dy and Gd is selected.

[0154] The contact between phosphate ions and rare earth ions in a liquid medium can be carried out, for example, by dissolving a compound that will serve as a rare earth ion source in a liquid medium containing phosphate ions, or by mixing a liquid medium containing phosphate ions with a solution containing rare earth ions. A solution containing rare earth ions can be prepared, for example, by dissolving a compound that will serve as a rare earth ion source in a solvent such as water. Compounds serving as rare earth ion sources are, for example, metal salts containing rare earth elements, and examples of anions constituting the metal salt include nitrate ions, sulfate ions, acetate ions, and chloride ions.

[0155] Contact between phosphate ions and rare earth ions in a liquid medium may include, for example, mixing a liquid medium containing phosphate ions, preferably further containing a reducing agent, and a first heat-treated product, a second heat-treated product, or a third heat-treated product to obtain a slurry; and mixing the slurry with a solution containing rare earth ions.

[0156] The content of rare earth ions in the liquid medium in which phosphate ions contact rare earth ions is, for example, 0.05% by mass or more or 0.1% by mass or more, and also, for example, 3% by mass or less or 2% by mass or less. Furthermore, the content of rare earth ions in the liquid medium relative to the amount of the first heat-treated material, the second heat-treated material, or the third heat-treated material is, for example, 0.2% by mass or more or 0.5% by mass or more, and also, for example, 30% by mass or less or 20% by mass or less. When the concentration of rare earth ions is above the aforementioned lower limit, there is a tendency for the adhesion rate of rare earth phosphates to the fluoride phosphor to further increase; when the concentration of rare earth ions is below the aforementioned upper limit, there is a tendency for rare earth phosphates to adhere more uniformly to the surface of the fluoride phosphor.

[0157] The contact temperature between phosphate ions forming rare earth phosphates and rare earth ions is, for example, 10°C to 50°C, preferably 20°C to 35°C. Furthermore, the contact time is, for example, 1 minute to 1 hour, preferably 3 minutes to 30 minutes. The contact can be carried out while the liquid medium is being stirred.

[0158] Following the attachment process, a separation process can be included to separate the luminescent material containing the fluoride phosphor with attached rare-earth phosphates from the liquid medium. Separation can be performed, for example, by solid-liquid separation methods such as filtration or centrifugation. The luminescent material obtained from the solid-liquid separation can be cleaned, dried, etc., as needed.

[0159] The method for manufacturing the luminescent material may further include, after the attachment step, a synthesis step of contacting a first heat-treated product, a second heat-treated product, or a third heat-treated product containing a fluoride phosphor with attached rare-earth phosphates in a liquid medium with a metal alkoxide containing at least one selected from Si, Al, Ti, Zr, Sn, and Zn, and disposing an oxide from the metal alkoxide on at least a portion of the surface of the fluoride phosphor with attached rare-earth phosphates contained in the first heat-treated product, the second heat-treated product, or the third heat-treated product. In the synthesis step, the amount of oxide disposed may be more than 2% by mass and less than 30% by mass relative to the luminescent material. Details of the synthesis step are as described above.

[0160] In the method for manufacturing luminescent materials, by attaching rare earth phosphates to the surface of a fluoride phosphor and then disposing of an oxide from a metal alkoxide on at least a portion of the surface of the fluoride phosphor with the rare earth phosphates attached, the resulting luminescent material tends to have further improved resistance to damp heat.

[0161] A method for manufacturing a luminescent material may include a surface treatment step of treating a fluoride phosphor obtained through a first heat treatment step, a second heat treatment step, a pressure heating treatment step, a synthesis step, or an attachment step with a coupling agent. Specifically, the method may include performing a silane coupling treatment on the fluoride phosphor contained in the first, second, or third heat-treated product. Alternatively, the method may include performing a silane coupling treatment after disposing an oxide from a metal alkoxide on at least a portion of the surface of the fluoride phosphor. Another method may include performing a silane coupling treatment after disposing a rare-earth phosphate on at least a portion of the surface of the fluoride phosphor. Furthermore, the method may include performing a silane coupling treatment after disposing a rare-earth phosphate on at least a portion of the surface of the fluoride phosphor and an oxide from a metal alkoxide on at least a portion of the surface of the fluoride phosphor. In the surface treatment process, by contacting the fluoride phosphor with a coupling agent, a surface treatment layer containing functional groups from the coupling agent can be applied to the surface of the fluoride phosphor. This, for example, improves the moisture resistance of the fluoride phosphor.

[0162] Specific examples of the coupling agent used in the surface treatment process are as described above. Furthermore, relative to the mass of the luminescent material, the amount of coupling agent used in the surface treatment process can be, for example, 0.5% by mass or more and 10% by mass or less, preferably 1% by mass or more and 5% by mass or less. The contact temperature between the fluoride phosphor and the coupling agent can be, for example, 0°C or more and 70°C or less, preferably 10°C or more and 40°C or less. The contact time between the fluoride phosphor and the coupling agent can be, for example, 1 minute or more and 10 hours or less, preferably 10 minutes or more and 1 hour or less.

[0163] Light-emitting device

[0164] The light-emitting device comprises a light-emitting material containing the aforementioned fluoride phosphor (hereinafter also referred to as the first light-emitting material) and a light-emitting element having a peak emission wavelength in the wavelength range of 380 nm to 485 nm. The light-emitting device may further include other constituent components as needed.

[0165] Hereinafter, an example of a light-emitting device will be described based on the accompanying drawings. Figure 2 This is a cross-sectional schematic diagram showing an example of the light-emitting device according to this embodiment. This light-emitting device is an example of a surface-mount type light-emitting device. The light-emitting device 100 includes: a light-emitting element 10 that emits light with a peak emission wavelength in the short wavelength range of visible light (e.g., 380 nm or more and 485 nm or less), and a molded body 40 on which the light-emitting element 10 is mounted. The molded body 40 has a first lead 20 and a second lead 30, and is integrally molded using a thermoplastic resin or a thermosetting resin. The molded body 40 forms a recess having a bottom surface and a side surface, and the light-emitting element 10 is mounted on the bottom surface of the recess. The light-emitting element 10 has a pair of positive and negative electrodes, which are electrically connected to the first lead 20 and the second lead 30 via wires 60. The light-emitting element 10 is covered within the recess by a fluorescent member 50. The fluorescent member 50 contains a wavelength conversion material 70 that converts the wavelength of light from the light-emitting element 10, and the wavelength conversion material includes at least a first light-emitting material. The fluorescent member 50 may include the first light-emitting material as the wavelength conversion material, and a second light-emitting material that emits light with a peak emission wavelength in a different wavelength range than the first light-emitting material upon excitation light from the light-emitting element 10.

[0166] Fluorescent components can include resin and wavelength conversion materials. Examples of resins constituting fluorescent components include silicone resin and epoxy resin. In addition to resin and wavelength conversion materials, fluorescent components can further include light-diffusing materials. By including light-diffusing materials, the directivity from the light-emitting element can be mitigated, and the viewing angle can be increased. Examples of light-diffusing materials include silicon oxide, titanium oxide, zinc oxide, zirconium oxide, and aluminum oxide.

[0167] The light-emitting element emits light with a peak emission wavelength in the short wavelength region of visible light, ranging from 380 nm to 485 nm. The light-emitting element can be an excitation source for exciting fluoride phosphors. Preferably, the light-emitting element has a peak emission wavelength in the range of 380 nm to 480 nm, more preferably in the range of 410 nm to 480 nm. Semiconductor light-emitting elements are preferably used as the excitation source. By using semiconductor light-emitting elements in the excitation source, a stable light-emitting device with high efficiency, high linearity of output relative to input, and strong resistance to mechanical shock can be obtained. For example, a semiconductor light-emitting element utilizing a nitride-based semiconductor can be used. The half-width of the emission peak in the emission spectrum of the light-emitting element is preferably, for example, 30 nm or less.

[0168] In a light-emitting device where the excitation source is covered by a fluorescent component containing a first luminescent material, a portion of the light emitted from the excitation source is absorbed by the first luminescent material containing a fluoride phosphor and emitted as red light. By using an excitation source that emits light with a peak emission wavelength in the range of 380 nm to 485 nm, the emitted light can be utilized more effectively, the loss of light emitted from the light-emitting device can be reduced, and a high-efficiency light-emitting device can be provided.

[0169] The light-emitting device preferably includes a first light-emitting material containing a fluoride phosphor, and further includes a second light-emitting material containing a phosphor other than the fluoride phosphor. The phosphor other than the fluoride phosphor only needs to absorb light from the light source and convert its wavelength to a different wavelength than that of the fluoride phosphor. The second light-emitting material can, for example, be included in the fluorescent component in the same way as the first light-emitting material.

[0170] The second luminescent material may have a peak emission wavelength in the wavelength range of 495 nm to 590 nm, and preferably includes at least one selected from β-thion phosphors, halosilicate phosphors, silicate phosphors, rare-earth aluminate phosphors, perovskite luminescent materials, and nitride phosphors. β-thion phosphors may, for example, have a composition represented by formula (IIa). Halosilicate phosphors may, for example, have a composition represented by formula (IIb). Silicate phosphors may, for example, have a composition represented by formula (IIc). Rare-earth aluminate phosphors may have a composition represented by formula (IId). Perovskite luminescent materials may, for example, have a composition represented by formula (IIe). Nitride phosphors may, for example, have a composition represented by formulas (IIIf), (IIg), or (IIh).

[0171] Si 6-t Al t O t N8-t Eu (IIa)

[0172] (In the formula, t is a number that satisfies 0 < t ≤ 4.2.)

[0173] (Ca,Sr,Ba)8MgSi4O 16 (F,Cl,Br)2:Eu (IIb)

[0174] (Ba,Sr,Ca,Mg)2SiO4:Eu (IIc)

[0175] (Y,Lu,Gd,Tb)3(Al,Ga)5O 12 :Ce (IId)

[0176] CsPb(F,Cl,Br,I)3 (IIe)

[0177] (La,Y,Gd)3Si6N 11 :Ce (IIf)

[0178] (Sr,Ca)LiAl3N4:Eu (IIg)

[0179] (Ca,Sr)AlSiN3:Eu (IIh)

[0180] In another aspect, the present invention includes the use of a fluoride phosphor in the manufacture of the aforementioned luminescent material or the aforementioned luminescent device, the fluoride phosphor having the aforementioned first composition and having a cubic crystal structure with a lattice constant of 0.8138 nm or higher. Additionally, the present invention includes the use of a fluoride phosphor in the manufacture of the aforementioned luminescent material or the aforementioned luminescent device, the fluoride phosphor having the aforementioned first composition and exhibiting an infrared absorption spectrum at 590 cm⁻¹. -1 Above and 610cm -1 The following wavenumber ranges exhibit absorption peaks. This invention also includes the use of the aforementioned luminescent material in the manufacture of the aforementioned luminescent device.

[0181] Example

[0182] The present invention will be specifically described below through embodiments, but the present invention is not limited to these embodiments.

[0183] Manufacturing Example 1: Manufacturing of the first fluoride particle

[0184] 7029 g of KHF2 was weighed and dissolved in 38.5 L of a 55% by mass HF aqueous solution to prepare a first solution. Separately, 1049.7 g of K2MnF6 was weighed and dissolved in 12.0 L of a 55% by mass HF aqueous solution to prepare a second solution. Next, 15.5 L of an aqueous solution containing 40% by mass H2SiF6 was prepared to prepare a third solution. Then, while stirring the first solution at room temperature, the second and third solutions were added dropwise over approximately 20 hours. After the addition was complete, 400 ml of 35% hydrogen peroxide solution was added, and the mixture was washed with pure water. The resulting precipitate was subjected to solid-liquid separation, washed with ethanol, and dried at 90°C for 10 hours, thereby producing the first fluoride particles of Manufacturing Example 1. The obtained first fluoride particles have a K2[Si]... 0.949 Mn 0.051 F6] represents the composition.

[0185] Example 1

[0186] 2200g of the first fluoride particles and 7.76g of the second fluoride particles were weighed and mixed such that the molar number of the second fluoride particles relative to the total molar number of the first and second fluoride particles manufactured in Manufacturing Example 1 was 0.003. The first fluoride particles had a K2[Si] content of 0.003. 0.949 Mn 0.051 A mixture of first and second fluoride particles was prepared, with the first fluoride particle having a composition represented by [F6] and the second fluoride particle having a composition represented by K3[AlF6]. The mixture of first and second fluoride particles was subjected to a first heat treatment in an inactive gas atmosphere with a nitrogen concentration of 100 vol% at a temperature of 700°C and a heat treatment time of 5 hours, yielding a first heat-treated product. The obtained first heat-treated product was thoroughly cleaned with cleaning water containing 1 wt% hydrogen peroxide. A second heat treatment was performed in a gas atmosphere with a fluoride (F2) concentration of 20 vol% and a nitrogen concentration of 80 vol%, bringing the cleaned first heat-treated product into contact with fluoride gas, and with the temperature set to 500°C and the heat treatment time set to 5 hours, producing the luminescent material of Example 1. It should be noted that the heat treatment time in the first and second heat treatments is the time elapsed from reaching the given heat treatment temperature until heating is stopped. The luminescent material of Example 1 has a composition represented by K2[Si]. 0.948 Al 0.002 Mn 0.050 F 5.998 The components represented by ]

[0187] Comparative Example 1

[0188] The product manufactured in Manufacturing Example 1 has K2[Si 0.949 Mn0.051 The first fluoride particles, represented by F6, were not mixed with second fluoride particles; only the first fluoride particles were used. Otherwise, the luminescent material was manufactured under the same conditions as in Example 1. The luminescent material of Comparative Example 1 has a composition of K2[Si] 0.950 Mn 0.050 F6] represents the composition.

[0189] Example 2

[0190] The mass of the second fluoride particles was changed to 15.57 g, so that the molar ratio of the second fluoride particles to the total molar ratio of the first and second fluoride particles was 0.006. Otherwise, the luminescent material was manufactured under the same conditions as in Example 1. The luminescent material of Example 2 has a K2[Si]... 0.946 Al 0.005 Mn 0.049 F 5.995 The components represented by ]

[0191] Example 3

[0192] The mass of the second fluoride particles was changed to 23.43 g, so that the molar ratio of the second fluoride particles to the total molar ratio of the first and second fluoride particles was 0.009. Otherwise, the luminescent material was manufactured under the same conditions as in Example 1. The luminescent material of Example 3 has a K2[Si]... 0.942 Al 0.008 Mn 0.050 F 5.992 The components represented by ]

[0193] Example 4

[0194] The mass of the second fluoride particles was changed to 39.28 g, so that the molar ratio of the second fluoride particles to the total molar ratio of the first and second fluoride particles was 0.015. Otherwise, the luminescent material was manufactured under the same conditions as in Example 1. The luminescent material of Example 4 has a K2[Si]... 0.939 Al 0.014 Mn 0.047 F 5.986 The components represented by ]

[0195] Example 5

[0196] The mass of the second fluoride particles was changed to 55.33 g, so that the molar ratio of the second fluoride particles to the total molar ratio of the first and second fluoride particles was 0.021. Otherwise, the luminescent material was manufactured under the same conditions as in Example 1. The luminescent material of Example 5 has a K2[Si] content of 0.021. 0.933 Al0.018 Mn 0.049 F 5.982 The components represented by ]

[0197] <Evaluation>

[0198] Chromaticity coordinates

[0199] For each luminescent material obtained in the examples and comparative examples, the emission spectra of each luminescent material at room temperature were measured by irradiating it with excitation light with a peak wavelength of 450 nm using a fluorescence spectrophotometer (product name: QE-2000, manufactured by Otsuka Electronics Co., Ltd.). Based on the emission spectrum data of each luminescent material in the examples and comparative examples, the xy chromaticity coordinates in the CIE (International Commission on Illumination) 1931 colorimetric system were determined. The results are shown in Table 1.

[0200] Relative brightness

[0201] Based on the emission spectrum data measured for each luminescent material of the obtained examples and comparative examples, the luminance of the luminescent material of Comparative Example 1 was set to 100%, and the luminance of the luminescent materials of Examples 1 to 5 was calculated in the form of relative luminance. The results are shown in Table 1.

[0202] composition

[0203] For each luminescent material obtained in the examples and comparative examples, compositional analysis based on inductively coupled plasma optical emission spectrometry (ICP-AES) was performed to calculate the molar ratio of each element when the potassium content in the composition was set to 2 moles. The results are shown in Table 1.

[0204] Angle of repose

[0205] For the luminescent materials of the obtained examples and comparative examples, the angle of repose was measured using an ABD powder property measuring instrument (product name: ABD-100 type, manufactured by Tsutsui Rikikaku Equipment Co., Ltd.), and the angle of repose was calculated based on the average of two measurements. The results are shown in Table 1.

[0206] Dispersion

[0207] For the luminescent materials of the obtained examples and comparative examples, the dispersity was measured three times using an ABD powder property analyzer (product name: ABD-100 type, manufactured by Ritsuko Chemical Equipment Co., Ltd., Tsutsui). The arithmetic mean of these measurements was taken as the dispersity. The results are shown in Table 1.

[0208] Bulk density

[0209] For the luminescent materials of the obtained examples and comparative examples, the bulk density was measured three times using an ABD powder property analyzer (product name: ABD-100 type, manufactured by Ritsuko Chemical Equipment Co., Ltd.), similar to the dispersity test. The arithmetic mean of these measurements was taken as the bulk density. The results are shown in Table 1.

[0210] Lattice constant

[0211] The luminescent materials of the obtained examples and comparative examples were mixed with Si standard samples at a 1:1 ratio. X-ray diffraction patterns were measured using a sample-level multifunctional X-ray diffractometer (product name: Ultima IV, manufactured by Rigaku Corporation), with an X-ray source of CuKα rays (λ = 0.15418 nm, tube voltage 40 kV, tube current 40 mA) under the following conditions: angle: 10°–70°, scan width: 0.02°, scan speed: 20° / min. Based on the X-ray diffraction patterns of the fluoride phosphors of Examples 1–5 and Comparative Example 1, the lattice constants were calculated using the integrated powder X-ray analysis software (PDXL2) and ICDD (International Center for Diffraction Data) card data (K2SiF6: 01-081-2264, Si: 00-027-1402). The results are shown in Table 1.

[0212] Table 1

[0213]

[0214] As shown in Table 1, the brightness of the luminescent materials in the embodiments is higher than that in the comparative examples. It can be presumed that this is due to the reduction of the F deficiency resulting from the partial substitution of Si with Al in the crystal structure of the luminescent materials in the embodiments. Furthermore, in the luminescent materials of the embodiments, the lattice constant increases with the increase of Al content. This can be considered to indicate that Si in the crystal structure is substituted with Al.

[0215] Infrared Spectroscopy: FT-IR Evaluation

[0216] The infrared absorption spectra of the fluoride phosphors obtained in the examples and comparative examples were measured by total internal reflection (ATR) using a Fourier transform infrared spectrometer (Japan Spectrophotometer; FT-IR-6200). Figure 3 A portion of the infrared absorption spectrum of the luminescent materials of Examples 1-5 and Comparative Example 1 is shown in magnified view. Additionally, for reference, Figure 6 The infrared absorption spectra of the first fluoride particle and the second fluoride particle are shown in the figure.

[0217] like Figure 3As shown, the luminescent material in the embodiment is at 590 cm⁻¹ -1 Above and 610cm -1 The wavenumber range below shows characteristic absorption peaks. On the other hand, no such absorption peaks were observed in the luminescent materials of the comparative examples. This can be interpreted as indicating that a portion of the Si in the crystal structure of the luminescent materials of the embodiments is replaced by Al.

[0218] SEM image

[0219] SEM images of the luminescent material were obtained using a scanning electron microscope (SEM). Figure 4 The image shows a SEM image of the luminescent material of Comparative Example 1. Figure 5 The image shows a SEM image of the luminescent material of Example 3.

[0220] and Figure 4 Compared to the luminescent material of Comparative Example 1 shown, in Figure 5 In the luminescent material of Example 3 shown, a fine difference in elevation is formed on the particle surface. It can be inferred that this makes it difficult for the particles to aggregate, thus reducing the angle of repose. As shown in Table 1, due to the state of the particle surface of such luminescent materials, compared with the luminescent materials of the comparative examples, the dispersion and packing density of the luminescent materials of the examples are increased. In the fluoride phosphors of Examples 1 to 5, the dispersion and packing density increase with the increase of Al content.

[0221] Example 1 of manufacturing a light-emitting device

[0222] The luminescent materials obtained in Example 3 or Comparative Example 1 were used as the first luminescent materials. Additionally, a material having a Si-based structure was used as the second luminescent material. 5.81 Al 0.19 O 0.19 N 7.81 A β-thionon phosphor with a composition represented by Eu and an emission peak wavelength around 540 nm was prepared. A phosphor 70 incorporating both a first and a second luminescent material was mixed with an organosilicon resin, with x around 0.280 and y around 0.270 in the CIE 1931 colorimetric system, to obtain a resin composition. Next, preparations were made as follows... Figure 2 The molded body 40 with a recess, as shown, has a light-emitting element 10 made of gallium nitride-based compound semiconductor with a peak emission wavelength of 451 nm disposed on a first lead 20 on the bottom surface of the recess. Then, the electrodes of the light-emitting element 10 are connected to the first lead 20 and the second lead 30 respectively by wires 60. Further, a resin composition is injected into the recess of the molded body 40 with a syringe to cover the light-emitting element 10, and the resin composition is cured to form a fluorescent component, thus manufacturing the light-emitting device 1.

[0223] Relative luminous flux

[0224] The luminous flux of the light-emitting device 1 using the luminescent material of Example 3 or Comparative Example 1 was measured using a total luminous flux measuring device employing an integrating sphere. The luminous flux of the light-emitting device 1 using the fluoride phosphor of Comparative Example 1 was set to 100%, and the luminous flux of the light-emitting device 1 using the luminescent material of Example 3 was calculated as a relative luminous flux. The results are shown in Table 2.

[0225] Table 2

[0226]

[0227] As shown in Table 2, the light-emitting device using the light-emitting material of Example 3, compared with the light-emitting device using the light-emitting material of Comparative Example 1, improved the relative luminous flux by using a light-emitting material with high luminous brightness.

[0228] Comparative Example 2

[0229] The luminescent material of Comparative Example 2, which has a Mn content of 1.5% by mass and a second theoretical composition (hereinafter sometimes simply referred to as "KSF") expressed as K2SiF6:Mn, was obtained by the same method as in Manufacturing Example 1.

[0230] Comparative Example 3

[0231] In a gas atmosphere with a fluorine (F2) concentration of 20 vol% and a nitrogen concentration of 80 vol%, the fluoride phosphor manufactured in Comparative Example 2 was brought into contact with fluorine gas, and a second heat treatment was performed at a temperature of 500°C for 8 hours, resulting in a luminescent material of Comparative Example 3 with a Mn content of 1.5 wt% and a second theoretical composition expressed as K2SiF6:Mn.

[0232] Example 6

[0233] First fluoride particles were obtained using the same method as in Manufacturing Example 1. These first fluoride particles were phosphors with a Mn content of 1.1% by mass and a second theoretical composition expressed as K₂SiF₆:Mn. The first and second fluoride particles were weighed and mixed such that the molar number of the second fluoride particles was 0.01 relative to the total molar number of the obtained first fluoride particles and the second fluoride particles with a composition expressed as K₃[AlF₆]. The mixture was subjected to a first heat treatment at 700°C for 5 hours in an inert gas atmosphere with a nitrogen concentration of 100% by volume, yielding a first heat-treated product. The obtained first heat-treated product was thoroughly cleaned with cleaning water containing 1% by mass of hydrogen peroxide, so that the Mn content was 1.1% by mass and the phosphor had a second theoretical composition expressed as K₂SiF₆:Mn.0.99 Al 0.01 F 5.99 The luminescent material of Example 6 was obtained by using the form of a fluoride phosphor representing the first theoretical composition of Mn.

[0234] Example 7

[0235] Liquid medium 1 was prepared by dissolving 6.7 g of KHF2 in 33.3 g of 55% hydrofluoric acid aqueous solution. Liquid medium 1 and 50 g of the fluoride phosphor prepared in Example 6 were added to an autoclave coated with fluororesin, and the mixture was subjected to a heat-pressurization treatment at 170°C and approximately 7.5 MPa for 8 hours. The resulting heat-pressurized material was thoroughly washed with washing water containing 1% by mass of hydrogen peroxide, followed by solid-liquid separation, ethanol washing, and drying at 90°C for 10 hours to obtain the luminescent material of Example 7.

[0236] Example 8

[0237] The first fluoride particles with a Mn content of 1.1% by mass and a second theoretical composition expressed as K2SiF6:Mn were obtained by the above method. In addition to using the obtained first fluoride particles, fluoride particles were obtained by performing a first heat treatment and cleaning in the same manner as in Example 6. These fluoride particles are phosphors with the first theoretical composition.

[0238] Next, in a gas atmosphere with a fluorine (F2) concentration of 20 vol% and a nitrogen concentration of 80 vol%, the obtained phosphor, i.e., fluoride particles, having the first theoretical composition, was brought into contact with fluorine gas, and a second heat treatment was performed at a temperature of 500°C for 8 hours, yielding the luminescent material of Example 8. This luminescent material has an Mn content of 1.0 wt% and a K2Si composition. 0.99 Al 0.01 F 5.99 Mn represents the first theoretical composition of fluoride phosphors.

[0239] Example 9

[0240] The above method yielded first fluoride particles with a Mn content of 1.6% by mass and a second theoretical composition expressed as K2SiF6:Mn. In addition to using the obtained first fluoride particles, the luminescent material of Example 9 was obtained by performing a first heat treatment, cleaning, and a second heat treatment in the same manner as in Example 8. This luminescent material has a Mn content of 1.5% by mass and a second theoretical composition expressed as K2SiF6:Mn. 0.99 Al 0.01 F 5.99 Mn represents the first theoretical composition of fluoride phosphors.

[0241] Example 10

[0242] A phosphor slurry was prepared by adding 15.0 g of 35% hydrogen peroxide solution and 735.0 g of pure water to 150.0 g of an aqueous solution of sodium phosphate (phosphate concentration: 2.4% by mass). The mixture was stirred at room temperature (using a stirrer at 400 rpm) while 300 g of the fluoride phosphor prepared in Example 9 was added.

[0243] Next, an aqueous solution of lanthanum nitrate (lanthanum concentration: 5.0% by mass), obtained by dissolving 23.4 g of lanthanum nitrate dihydrate in 156.6 g of pure water, was added dropwise to the phosphor slurry over approximately 1 minute. Stirring was stopped approximately 30 minutes after the addition was completed, and the mixture was allowed to stand. After removing the supernatant, it was thoroughly washed with washing water containing 1% by mass of hydrogen peroxide. The resulting precipitate was subjected to solid-liquid separation, washed with ethanol, and dried at 90°C for 10 hours, thereby producing the luminescent material of Example 10 with lanthanum phosphate deposited on its surface.

[0244] Example 11

[0245] In addition to using the fluoride phosphor manufactured in Example 8, the luminescent material of Example 11, with lanthanum phosphate disposed on its surface, was prepared by the same method as in Example 10.

[0246] Example 12

[0247] The first fluoride particles with a Mn content of 1.3% by mass and a second theoretical composition expressed as K2SiF6:Mn were obtained using the above method. In addition to using the obtained first fluoride particles, a fluoride phosphor was obtained by performing a first heat treatment, cleaning, and a second heat treatment in the same manner as in Example 8. This fluoride phosphor has a Mn content of 1.2% by mass and a second theoretical composition expressed as K2SiF6:Mn. 0.99 Al 0.01 F 5.99 Mn represents the phosphor with the first theoretical composition. Except for using the obtained fluoride phosphor with the first theoretical composition, the luminescent material of Example 12, with lanthanum phosphate disposed on its surface, was prepared by the same method as in Example 10.

[0248] Comparative Example 4

[0249] Except for the fluoride phosphor manufactured in Comparative Example 3, the luminescent material of Comparative Example 4, on which lanthanum phosphate was disposed on the surface, was prepared by the same method as in Example 10.

[0250] Example 13

[0251] 100g of the fluoride phosphor prepared in Example 6 was weighed and added to a solution consisting of 180ml of ethanol, 43.4ml of ammonia water containing 16.5% by mass of ammonia, and 20ml of pure water. The solution was stirred at 300rpm with a stirrer while maintaining room temperature, serving as the mother liquor. 35.7g of tetraethoxysilane (TEOS: Si(OC2H5)4) was weighed and added dropwise to the stirred mother liquor over approximately 3 hours. Stirring was then continued for 1 hour, followed by the addition of 10g of 35% by mass hydrogen peroxide (H2O2), after which stirring was stopped. The resulting precipitate was subjected to solid-liquid separation, washed with ethanol, and dried at 105°C for 10 hours, thus producing the luminescent material of Example 13 coated with silica (SiO2). It should be noted that the amount of tetraethoxysilane added relative to the fluoride particles was approximately 10% by mass (converted to silica).

[0252] Example 14

[0253] Except for the fluoride phosphor manufactured in Example 7, the luminescent material of Example 14 was prepared by the same method as in Example 13.

[0254] Example 15

[0255] 300g of the fluoride phosphor prepared in Example 8 was weighed and added to a solution consisting of 540ml of ethanol, 130.2ml of ammonia water containing 16.5% by mass of ammonia, and 60ml of pure water. The solution was stirred at 350rpm with a stirrer while maintaining room temperature as the mother liquor. The amount of tetraethoxysilane (TEOS: Si(OC2H5)4) added was set to 107.1g, and the addition time was set to 6 hours. Otherwise, the luminescent material of Example 15 was prepared using the same method as in Example 13. The content was approximately 10% by mass relative to the fluoride particles, converted to silicon dioxide.

[0256] Example 16

[0257] The fluoride phosphor manufactured in Example 9 was used, and the stirring speed was set to 500 rpm. Otherwise, the luminescent material of Example 16 was prepared by the same method as in Example 15.

[0258] Example 17

[0259] Except for the fluoride phosphor manufactured in Example 10, the luminescent material of Example 17 was prepared by the same method as in Example 16.

[0260] Example 18

[0261] 50 g of the luminescent material prepared in Example 17 was weighed. Next, 84.9 ml of ethanol, 5.8 ml of pure water, and decyltrimethoxysilane ((CH3O)3Si(CH2)9CH3) as a silane coupling agent were mixed and stirred for 30 minutes, then allowed to stand for at least 20 hours. The fluoride phosphor E10 prepared in Example 10 was added to this solution, and the mixture was stirred at 200 rpm for 1 hour, after which stirring was stopped. The resulting precipitate was subjected to solid-liquid separation and dried at 105°C for 10 hours to perform silane coupling treatment, yielding the luminescent material of Example 18.

[0262] Example 19

[0263] Except that the amount of tetraethoxysilane added was set to 64.3 g, the luminescent material of Example 19 was obtained by the same method as in Example 15.

[0264] Example 20

[0265] Except that the amount of tetraethoxysilane added was set to 32.2 g, the luminescent material of Example 20 was obtained by the same method as in Example 15.

[0266] Example 21

[0267] Except for the luminescent material manufactured in Example 11, the fluoride phosphor E16 of Example 21 was produced by the same method as in Example 15.

[0268] Example 22

[0269] Except for the luminescent material prepared in Example 21, the luminescent material of Example 22 was prepared by the same method as in Example 18.

[0270] Example 23

[0271] Except for the luminescent material manufactured in Example 12, a luminescent material was obtained by the same method as in Example 19. Hexyltrimethoxysilane was used as a silane coupling agent in the obtained luminescent material. Otherwise, the luminescent material of Example 23 was obtained by silane coupling treatment performed by the same method as in Example 18.

[0272] Example 24

[0273] Except that vinyltrimethoxysilane was used as a silane coupling agent, the luminescent material of Example 24 was obtained by the same method as in Example 23.

[0274] Example 25

[0275] Except that 3-aminopropyltriethoxysilane was used as a silane coupling agent, the luminescent material of Example 25 was obtained by the same method as in Example 23.

[0276] Example 26

[0277] Except for the use of 3-epoxypropoxypropyltrimethoxysilane as a silane coupling agent, the luminescent material of Example 26 was obtained by the same method as in Example 23.

[0278] evaluate

[0279] (1) Infrared Spectroscopy: FT-IR Evaluation

[0280] For the luminescent materials obtained in Example 6 and Comparative Examples 2 and 3, the infrared absorption spectra were measured by diffuse reflectance method using a Fourier transform infrared spectrometer iS (Thermo Fisher Scientific) with a KBr background. A 4000 cm⁻¹ spectral density was used. -1 The values ​​below were used as a baseline for correction, and a Kubelka-Munk conversion was performed. The peak was then normalized to the maximum value, and the absorption spectrum was measured.

[0281] Focusing on the measured absorption spectrum at 1050 cm⁻¹ -1 Above and 1350cm -1 Below and 3500cm -1 Above and 3800cm -1 For the peak components in the following wavenumber ranges, the integral area (IR peak area) of each peak was calculated. Furthermore, the IR peak area ratio Z1 was calculated as an area ratio expressed by the following formula (P). It should be noted that for 3500 cm⁻¹... -1 Above and 3800cm -1 In terms of peak area, it will connect 3000cm -1 The strength below 3800cm -1 The area is calculated by using the straight line of lower intensity as the background, for a line of 1050cm². -1 Above and 1350cm -1 Regarding the peak area below, it will connect to 1050cm. -1 The strength below 1350cm -1 The area is calculated by using a straight line of intensity as the background. Here, we can consider 1050cm² as the area. -1 Above and 1350cm -1 The following is from fluoride phosphors, 3000cm -1 Above and 3800cm -1 The following comes from H2O, 3500cm -1 Above and 3800cm -1The following is from Si-OH.

[0282] Z1=(3500cm -1 Above and 3800cm -1 (The following peak area) / (1050cm²) -1 Above and 1350cm -1 The following peak area (P)

[0283] The results are shown in Table 3.

[0284] (2) Amount of silicon dioxide

[0285] For each obtained luminescent material, compositional analysis based on ICP emission spectrophotometry was performed. The amount of silica coating on the fluoride phosphors was calculated based on the difference between the analytical Si concentration of the silica-coated luminescent materials obtained in Examples 13-26 and the analytical Si concentration of the fluoride phosphors before silica coating in Examples 6-12. The silica content relative to the luminescent material (SiO2 analytical value) was then determined. The results are shown in Tables 3-7.

[0286] (3) Fluorescence X-ray elemental analysis: XRF evaluation

[0287] For the luminescent materials obtained in Examples 9 and 16, the peak intensity of the Kα rays of element F was determined by X-ray fluorescence spectrometry using an XRF apparatus (product name: ZSX Primus II, manufactured by Rigaku Corporation). The peak intensity of the fluoride phosphor of Example 9 was set to 100, and the peak intensity ratio of the luminescent material of Example 16 was calculated as a relative value. The average thickness of the silica film of the luminescent material of Example 16 was calculated using the CXRO (The Center for X-Ray Optics) database based on the obtained peak intensity ratios. The results are shown in Table 3.

[0288] (4) Scanning electron microscopy observation

[0289] The luminescent material of Example 17 was imaged using scanning electron microscopy (SEM). The SEM images are shown below. Figure 8 Furthermore, for the luminescent material of Example 17, an arbitrary cross-section was observed using a scanning electron microscope (SEM), and image analysis was performed to measure the average thickness of the silica film. Specifically, multiple luminescent material particles were embedded in resin, and cross-sectional samples were fabricated by ion milling, ensuring that the cross-section of the luminescent material particles could be observed using a scanning electron microscope. The cross-sectional SEM images are shown below. Figure 7 .

[0290] For the obtained cross-sectional SEM images, the thickness of the silica film at five locations was measured for each luminescent material particle. The measured average thickness was calculated as the arithmetic mean of the thicknesses at a total of 25 locations for the five particles. Here, the silica film thickness refers to the thickness of the film observable on the SEM image, including portions of the film cut at an angle relative to the thickness direction. The results are shown in Table 4.

[0291] (5) Total Carbon Content (TC)

[0292] The total carbon content (TC) of the luminescent materials obtained in Examples 10, 18, 22-26 and Comparative Example 4 was analyzed using a total organic carbon analyzer (product name: TOC-L, manufactured by Shimadzu Corporation). The results are shown in Tables 4, 6 and 7.

[0293] (6) Lanthanum content

[0294] For the luminescent materials obtained in Examples 10-12, 17, 18, 21-26 and Comparative Example 4, the lanthanum content was analyzed by inductively coupled plasma optical emission spectrometry (ICP-AES), and the content relative to the luminescent material (La analysis value) was determined. The results are shown in Tables 4-7.

[0295] (7) Manganese content

[0296] For the luminescent materials of Examples 11, 12, 15, 19-26 and Comparative Examples 3 and 4, the manganese content was analyzed by inductively coupled plasma optical emission spectrometry (ICP-AES), and the content (Mn analysis value) relative to the luminescent material was determined. The results are shown in Tables 5 to 7.

[0297] (8) Evaluation of quality changes in resin composition

[0298] The effect of the luminescent material on the mass change of the resin composition containing the resin and the luminescent material was evaluated as follows. A resin composition was prepared by mixing the luminescent material at 33% by mass relative to the silicone resin. Approximately 1 g of the obtained resin composition was weighed onto an aluminum foil, cured, and the difference between the mass of the cured resin composition and the mass of the aluminum foil was calculated as the initial value. The cured resin composition on the aluminum foil was placed in a small oven (product name: LH-114 thermo-humidifier, manufactured by ESPEC) maintained at 200°C, and the mass was measured after 100 hours, 300 hours, 500 hours, and 1000 hours. The mass retention rate (%) of the resin composition after each time period was calculated with the initial value set to 100%. A higher mass retention rate indicates that the reaction between the luminescent material and the resin is more inhibited, meaning that the resin composition has better durability. It should be noted that the silicone resin used in the evaluation was selected from commercially available silicone resins. Specifically, for Examples 6-26 and Comparative Examples 2, 3, and 4, dimethyl silicone resin (product name KER-2936; refractive index 1.41, hereinafter referred to as "dimethyl silicone resin 1") manufactured by Shin-Etsu Chemical Industry Co., Ltd. was evaluated. In addition, for Examples 15, 21, and Comparative Example 3, evaluations were also conducted using dimethyl silicone resin (trade name OE-6351; refractive index 1.41, hereinafter also referred to as "dimethyl silicone resin 2") manufactured by Dow Corning Toray, phenyl silicone resin (trade name OE-6630; refractive index 1.53, hereinafter also referred to as "phenyl silicone resin 1"), and a phenyl silicone resin with a different refractive index than phenyl silicone resin 1 (refractive index 1.50, hereinafter also referred to as "phenyl silicone resin 2").

[0299] (9) Durability evaluation

[0300] The durability of the luminescent materials obtained above was evaluated as follows. For each luminescent material, the internal quantum efficiency for excitation light at 450 nm was measured using a quantum efficiency measuring device (product name: QE-2000, manufactured by Otsuka Electronics Co., Ltd.), and this was used as the initial characteristic. Next, the luminescent materials were placed in glass petri dishes and allowed to stand for 100 hours in a small high-temperature, high-humidity bath (ESPEC) maintained at 85°C and 85% relative humidity. Then, the internal quantum efficiency of each luminescent material was measured using the same method, and the quantum efficiency retention rate (%) was calculated when the initial characteristic was set to 100%. A higher quantum efficiency retention rate indicates better durability. The results are shown in Tables 3 to 7.

[0301] Example 2 of manufacturing a light-emitting device

[0302] The luminescent materials of Examples 6-10, 16-18, and Comparative Examples 2-4 were used as the first luminescent material. As the second luminescent material, a material having a Si-based structure was used. 5.81 Al 0.19 O 0.19 N 7.81 The composition is represented by Eu, and it has a peak emission wavelength around 540 nm. A luminescent material 70, incorporating a first luminescent material 71 and a second luminescent material 72, was mixed with silicone resin to obtain a resin composition, with chromaticity coordinates around 0.280 x and 0.270 in the CIE 1931 colorimetric system. Next, a molded body 40 with a recess was prepared. A luminescent element 10, made of a gallium nitride-based compound semiconductor with a peak emission wavelength of 451 nm, was disposed on a first lead 20 on the bottom surface of the recess. Then, the electrodes of the luminescent element 10 were connected to the first lead 20 and the second lead 30 respectively using wires 60. Further, the resin composition was injected into the recess of the molded body 40 using a syringe to cover the luminescent element 10, and the resin composition was cured to form a fluorescent component, thus manufacturing the luminescent device 2.

[0303] Example 3 of manufacturing a light-emitting device

[0304] The luminescent materials of Examples 11, 12, 15, 19-26, and Comparative Example 4 were used as the first luminescent material. As the second luminescent material, a combination of materials containing Lu3Al5O4 was used. 11 A rare-earth aluminate phosphor with a theoretical composition represented by Ce and an emission peak around 530 nm, exhibiting Y3Al5O 11 The light-emitting device 3 was manufactured in the same manner as in Example 1, using a rare-earth aluminate phosphor with a theoretical composition represented by Ce and an emission peak near 535 nm, and a nitride phosphor with a theoretical composition represented by (Ca,Sr)AlSiN3:Eu and an emission peak wavelength near 630 nm. A resin composition was obtained by mixing a light-emitting material 70 containing a first light-emitting material 71 and a second light-emitting material 72 with an organosilicon resin, with x around 0.459 and y around 0.411 in the CIE 1931 colorimetric system.

[0305] Durability Evaluation 1

[0306] Light-emitting devices 2 using the light-emitting materials obtained through Examples 9, 10, 16-18 and Comparative Examples 3, and light-emitting devices 3 using the light-emitting materials obtained through Examples 12, 23-26, were subjected to a durability test 1 after being stored in an environmental testing chamber at 85°C and 85% relative humidity for 500 hours. The luminous flux retention rate 1 (%) of the light-emitting devices after durability test 1 was determined when the luminous flux of the light-emitting devices before durability test 1 was set to 100%. A higher luminous flux retention rate 1 indicates better durability under high heat and high humidity. The results are shown in Tables 3, 4, and 7.

[0307] Durability Evaluation 2

[0308] For the light-emitting devices 3 using the light-emitting materials obtained in Examples 11, 12, 15, 19-26 and Comparative Example 4, a durability test 2 was conducted in an environmental testing machine at 85°C without humidification, driven by a current of 150mA for 1000 hours. The luminous flux retention rate 2 (%) of the light-emitting device after durability test 2, with the luminous flux of the light-emitting device before durability test 2 set to 100%, was determined. A higher luminous flux retention rate 2 indicates better durability against high heat. The results are shown in Tables 6 and 7.

[0309] Durability test 3

[0310] For the light-emitting devices 2 using the light-emitting materials obtained in Examples 6-8 and Comparative Examples 2 and 3, the x-values ​​in the chromaticity coordinates were measured in an environmental testing chamber at 85°C without humidification for 100 hours and 500 hours when driven with a current of 150 mA. Using the x-value at 100 hours as the initial value, the change in x at 500 hours was defined as Δx. A smaller Δx indicates better color stability under high heat. The results are shown in Table 3.

[0311] Table 3

[0312]

[0313] Table 4

[0314]

[0315] Table 5

[0316]

[0317] Table 6

[0318]

[0319] Table 7

[0320]

[0321] If the amount of SiO2 added increases, the SiO2 analysis value of the luminescent materials in Examples 15, 19, and 20 increases. The peak intensity of Kα rays from element F based on XRF in the luminescent material of Example 16 is reduced to 42 compared to the peak intensity of 100 in the luminescent material of Example 9. Therefore, it can be considered that the Kα rays from element F are absorbed by the SiO2 film, and that SiO2 coats the surface of the fluoride particles in the form of a film. Furthermore, the film thickness of the SiO2 film is calculated to be 0.45 μm based on the absorption rate.

[0322] Compared to the luminescent material with the second theoretical composition (KSF) in Comparative Example 2, the luminescent material with the first theoretical composition (KSAF) in Example 6 has a smaller peak area ratio (Z1) in FT-IR. Compared to the luminescent device 2 using the luminescent material (KSF) of Comparative Examples 2 and 3, the luminescent device 2 using the luminescent material (KSAF) of Examples 6-8 has a smaller Δx. This indicates that even without a second heat treatment, KSAF has fewer -OH groups on its particle surface, resulting in superior color stability compared to KSF. In other words, the first, second, and third heat-treated products of KSAF exhibit excellent color stability. Compared to the resin compositions containing the luminescent materials of Comparative Examples 2, 3, and Examples 6-9, the resin compositions containing the luminescent materials with SiO2 films of Examples 13-16 have higher mass retention and superior durability. It can be seen that, regarding the durability of the resin composition, compared with Example 20, which has a thin average thickness of SiO2 film, Examples 19 and 15, which have a thick average thickness, further improved the mass retention rate of the resin composition at 1000 hours, and further improved the durability of the resin composition.

[0323] Compared to the light-emitting device 2 using the light-emitting material of Comparative Example 3, the light-emitting device 2 using the light-emitting material of Example 16 has a higher luminous flux retention rate 1 and superior durability. Therefore, it can be seen that, among light-emitting devices, those using fluoride phosphors coated with SiO2 films exhibit higher durability.

[0324] The SEM image obtained by observing the luminescent material obtained in Example 17 using a scanning electron microscope is shown below. Figure 7 .according to Figure 7 It can be seen that the silica coated with fluoride particles with the KSAF theoretical composition is not in the form of particles, but becomes a continuous film.

[0325] The image obtained by observing the cross-section of the luminescent material obtained in Example 17 using a scanning electron microscope is shown below. Figure 8 .exist Figure 8In the diagram, the gray portion corresponds to fluoride particle 2, the white portion corresponds to lanthanum phosphate 4, and the dark gray portion corresponds to silicon dioxide 6. This indicates that lanthanum phosphate 4 is attached to fluoride particle 2 and further coated with silicon dioxide 6.

[0326] The TC analysis values ​​of the luminescent materials in Examples 18 and 22-26 were increased compared to those in Comparative Example 4, confirming the presence of carbon. Since this carbon is believed to originate from the silane coupling agent, it can be assumed that the components from the silane coupling agent adhered to the surface of the fluoride phosphor through silane coupling treatment of the SiO2-coated fluoride phosphor.

[0327] Compared to the luminescent material of Example 10, which had lanthanum phosphate attached to a fluoride phosphor, the luminescent material of Example 17, which was covered with a SiO2 film, showed higher quantum efficiency retention and resin composition mass retention in its durability evaluation, indicating superior durability of both the luminescent material and the resin composition. It can be seen that, regarding durability, compared to Example 17, Example 18, which underwent silane coupling treatment, showed a further increase in quantum efficiency retention and improved durability. Compared to Example 16, which did not have lanthanum phosphate attached, Example 17, which had lanthanum phosphate attached, showed a higher quantum efficiency retention, achieving a superior effect by coating the surface of the phosphor with lanthanum phosphate attached with SiO2. In other words, the fluoride phosphor with lanthanum phosphate attached also achieved improved durability by coating it with a SiO2 film.

[0328] Compared to the light-emitting device 2 using the light-emitting material of Example 10, the light-emitting device 2 using the light-emitting materials of Examples 17 and 18 showed a further improvement in durability. The fluoride particles with attached lanthanum phosphate were also coated with a SiO2 film to improve durability.

[0329] The sedimentation state of the phosphor was confirmed by observing the cross-section of the light-emitting device. In light-emitting device 2, which used the luminescent material of Example 18 that had undergone silane coupling treatment, the luminescent material showed the greatest sedimentation. It can be assumed that the silane coupling treatment increases the affinity with the resin, making the luminescent material easier to settle.

[0330] Compared to the luminescent material of Comparative Example 3, the luminescent materials of Examples 15 and 21 exhibited higher quantum efficiency retention. Furthermore, compared to the luminescent material of Comparative Example 3, the resin compositions of the luminescent materials of Examples 15 and 21 showed improved mass retention and superior durability. For phenyl silicone resins 1 and 2, although the mass retention of the fluoride particles in Comparative Example 3 was also higher, the mass retention of Examples 15 and 21 was even higher. While the mass retention of the luminescent material in Comparative Example 3 was significantly reduced when using dimethyl silicone resins 1 and 2, the mass retention was high in Examples 15 and 21. In particular, the mass retention of Example 21 was further improved by coating the surface of the phosphor with lanthanum phosphate using a SiO2 film, resulting in a higher effect. For any resin, compared to the fluoride particles containing KSF in the composition of Comparative Example 3, the resin compositions of Example 15 (which had fluoride particles containing KSAF in the composition) and Example 21 (which had the surface of the phosphor with lanthanum phosphate attached using a SiO2 film) exhibited superior durability.

[0331] Compared to the luminescent material of Comparative Example 4, the luminescent materials of Examples 15, 19-22 exhibited higher quantum efficiency retention. The mass retention of the resin composition was also improved, resulting in excellent durability. The luminescent device 3 using the luminescent materials of Examples 15, 19-22 showed higher luminous flux retention and superior durability compared to the luminescent device 3 using the luminescent material of Example 11. The luminescent devices 3 using the luminescent materials of Examples 21 and 22 employed luminescent materials with a SiO2 coating on the surface of a phosphor with attached lanthanum phosphate, exhibiting superior durability compared to the luminescent device using the luminescent material of Example 15. This can be attributed to the improved adhesion of the silica coating layer by lanthanum phosphate, which inhibits coating peeling. Furthermore, for the luminescent device 3 using the luminescent material of Example 22, the increased affinity with the resin through silane coupling treatment facilitated phosphor deposition and improved resin adhesion, resulting in superior performance. Compared to the light-emitting device using the fluoride phosphor of Example 15, the light-emitting devices using the light-emitting materials of Examples 19 and 20, which have reduced SiO2 concentration, exhibit superior durability. This can be attributed to the fact that reducing the SiO2 concentration suppresses cracking of the SiO2 film, thereby reducing contact between the cracked areas and the external environment. Compared to the light-emitting device using Comparative Example 4, which uses fluoride particles with a KSF composition and coated with lanthanum phosphate, the light-emitting devices 3 using the light-emitting materials of Examples 19 and 20, which use SiO2 films coated with fluoride particles with a KSAF composition and coated with lanthanum phosphate, and the light-emitting devices 3 using the light-emitting materials of Examples 211 and 22, which use SiO2 films coated with fluoride particles with a KSAF composition and coated with lanthanum phosphate, exhibit even better durability.

[0332] Compared to the luminescent material of Example 12, the luminescent materials of Examples 23-26 exhibit higher quantum efficiency retention. The resin composition also shows higher mass retention and excellent durability as a powder, suggesting that the affinity with the resin is improved through silane coupling treatment. In durability evaluation 1, compared to the luminescent device using the luminescent material of Example 12, the luminous flux retention rate 1 of the luminescent device using the luminescent materials of Examples 23, 24, and 26 is higher. Furthermore, in durability evaluation 2, compared to the luminescent device using the luminescent material of Example 12, the luminous flux retention rate 2 of the luminescent device using the luminescent materials of Examples 23-26 is higher. The main reason for this can be considered, for example, that silane coupling agents undergo chemical bonding upon heating by hydrolyzing methoxy or ethoxy groups, where the -OH groups on the phosphor surface bond with hydrogen. Therefore, silane coupling agents are less likely to bond with fluoride particles composed of KSAF, which have fewer -OH groups on their surface. On the other hand, it can be considered that the surface of the fluoride phosphor coated with fluoride particles using SiO2 contains a large number of -OH groups, which facilitates the bonding of the silane coupling agent and further enhances its affinity with the resin, thereby achieving the effects described above. In particular, for the luminescent materials of Examples 23-26, the surface of the phosphor with attached lanthanum phosphate is coated with SiO2. It can be considered that the lanthanum phosphate further improves the adhesion of the SiO2 film and further suppresses cracking and peeling of the coating layer. Therefore, the silane coupling agent can easily and uniformly bond, further enhancing its affinity with the resin.

[0333] The fluoride phosphors and luminescent materials obtained by the manufacturing method of this disclosure are particularly suitable for use in light-emitting devices that use light-emitting diodes as excitation sources. For example, they can be suitably used as light sources, signal devices, lighting switches, various sensors, various indicators, and small flashlights for lighting applications, LED displays, or LCD backlights.

[0334] The disclosures of Japanese Patent Application No. 2021-091754 (filed May 31, 2021), Japanese Patent Application No. 2021-130074 (filed August 6, 2021), Japanese Patent Application No. 2021-141629 (filed August 31, 2021), and Japanese Patent Application No. 2022-083514 (filed May 23, 2022) are incorporated herein by reference in their entirety. All documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as those specifically described separately.

Claims

1. A luminescent material comprising a fluoride phosphor, The fluoride phosphor has a first composition comprising: an alkali metal containing K, Si, Al, Mn, and F, wherein, with the total molar number of the alkali metal set to 2, the total molar number of Si, Al, and Mn is 0.9 or more and 1.1 or less, the molar number of Al is greater than 0 and less than 0.1, the molar number of Mn is greater than 0 and less than 0.2, and the molar number of F is 5.5 or more and less than 6.

0. The fluoride phosphor has a cubic crystal structure with a lattice constant of 0.8138 nm or higher. The luminescent material further comprises an oxide disposed on at least a portion of the surface of the fluoride phosphor. The oxide comprises at least one selected from Si, Al, Ti, Zr, Sn, and Zn. The content of the oxide is more than 2% by mass and less than 30% by mass relative to the luminescent material.

2. A luminescent material comprising a fluoride phosphor, The fluoride phosphor has a first composition comprising: an alkali metal containing K, Si, Al, Mn, and F, wherein, with the total molar number of the alkali metal set to 2, the total molar number of Si, Al, and Mn is 0.9 or more and 1.1 or less, the molar number of Al is greater than 0 and less than 0.1, the molar number of Mn is greater than 0 and less than 0.2, and the molar number of F is 5.5 or more and less than 6.

0. The fluoride phosphor exhibits infrared absorption at 590 cm⁻¹. -1 Above and 610cm -1 The following wavenumber range has absorption peaks. The luminescent material further comprises an oxide disposed on at least a portion of the surface of the fluoride phosphor. The oxide comprises at least one selected from Si, Al, Ti, Zr, Sn, and Zn. The content of the oxide is more than 2% by mass and less than 30% by mass relative to the luminescent material.

3. The luminescent material according to claim 1 or 2, wherein, The fluoride phosphor has a composition represented by the following formula (I), M2[Si p Al q Mn r F s (I) In equation (I), M represents an alkali metal and includes at least K, and p, q, r and s satisfy 0.9≤p+q+r≤1.1, 0<q≤0.1, 0<r≤0.2, and 5.5≤s<6.

0.

4. The luminescent material according to claim 1 or 2, wherein, In the first composition, with the total number of alkali metals set to 2, the total number of Si, Al and Mn is 1.

5. The luminescent material according to claim 1 or 2, wherein, The number of moles of Al in the first composition is greater than 0 and less than 0.

06.

6. The luminescent material according to claim 1, wherein, The fluoride phosphor has a rare earth phosphate containing at least one rare earth element selected from La, Ce, Dy and Gd disposed on its surface, and the oxide is disposed on at least a portion of the surface of the fluoride phosphor, with the rare earth phosphate sandwiched between them.

7. The luminescent material according to claim 1 or 2, further comprising a rare earth phosphate disposed on at least a portion of the surface of the fluoride phosphor. The rare earth phosphate contains at least one rare earth element selected from La, Ce, Dy and Gd.

8. A method for manufacturing a luminescent material, the method comprising: Prepare first fluoride particles having a second composition, the second composition comprising: an alkali metal containing K, Si, Mn and F, wherein when the total molar number of the alkali metal is set to 2, the total molar number of Si and Mn is 0.9 or more and 1.1 or less, the molar number of Mn is greater than 0 and less than 0.2, and the molar number of F is 5.5 or more and less than 6.

0. Prepare a second fluoride particle having a third composition, the third composition comprising: an alkali metal containing K, Al and F, wherein when the molar number of Al is set to 1, the total molar number of the alkali metal is 2 or more and 3 or less, and the molar number of F is 5 or more and 6 or less. A first heat-treated product is obtained by subjecting a mixture of the first fluoride particles and the second fluoride particles to a first heat treatment at a temperature of 600°C or higher and 780°C or lower in an inactive gas atmosphere. A second heat-treated product is obtained by subjecting the first heat-treated product to a second heat treatment at a temperature of 400°C or higher but lower than 600°C. The second heat-treated product contains a fluoride phosphor. By contacting the second heat-treated material with a metal alkoxide comprising at least one selected from Si, Al, Ti, Zr, Sn and Zn in a liquid medium, an oxide from the metal alkoxide is disposed on at least a portion of the surface of the fluoride phosphor in an amount of 2% by mass or more and 30% by mass or less relative to the luminescent material.

9. The method for manufacturing the luminescent material according to claim 8, wherein, In the process of preparing the first fluoride particles, in the second composition, when the total number of moles of alkali metal is set to 2, the total number of moles of Si and Mn is 1.

10. The method for manufacturing the luminescent material according to claim 8 or 9, the method further comprising: The first heat-treated material is brought into contact with a first liquid medium used to remove impurities.

11. The method for manufacturing the luminescent material according to claim 9, the method comprising: The second heat-treated material, a rare earth ion containing at least one of La, Ce, Dy and Gd, and phosphate ions are brought into contact in a liquid medium to obtain a second heat-treated material with rare earth phosphates disposed on at least a portion of its surface.

12. The method for manufacturing the luminescent material according to claim 11, the method further comprising: By contacting the second heat-treated object containing rare earth phosphates with a metal alkoxide containing at least one selected from Si, Al, Ti, Zr, Sn and Zn in a liquid medium, an oxide from the metal alkoxide is disposed on at least a portion of the surface of the second heat-treated object to which the rare earth phosphates are attached, in an amount of 2% by mass or more and 30% by mass or less relative to the luminescent material.

13. The method for manufacturing the luminescent material according to claim 8 or 9, the method further comprising: The first heat-treated material is subjected to pressure treatment and heating treatment together with the second liquid medium to obtain the third heat-treated material.

14. The method for manufacturing the luminescent material according to claim 13, wherein, The heat treatment is performed at a temperature of 100°C or higher.

15. The method for manufacturing the luminescent material according to claim 13, wherein, The pressurization process is performed at a pressure of 1.6 MPa or higher.

16. The method for manufacturing the luminescent material according to claim 13, wherein, The second liquid medium contains water.

17. The method for manufacturing the luminescent material according to claim 13, wherein, The second liquid medium contains potassium.

18. The method for manufacturing the luminescent material according to claim 13, the method comprising: By contacting the third heat-treated material with a metal alkoxide comprising at least one selected from Si, Al, Ti, Zr, Sn and Zn in a liquid medium, an oxide from the metal alkoxide is disposed on at least a portion of the surface of the fluoride phosphor in an amount of 2% by mass or more and 30% by mass or less relative to the luminescent material.

19. The method for manufacturing the luminescent material according to claim 13, the method comprising: The third heat-treated material, a rare earth ion containing at least one of La, Ce, Dy and Gd, and phosphate ions are brought into contact in a liquid medium to obtain a second heat-treated material on which at least a portion of the surface is disposed of with rare earth phosphate.

20. The method for manufacturing the luminescent material according to claim 19, the method further comprising: By contacting a third heat-treated object containing the rare earth phosphate with a metal alkoxide containing at least one selected from Si, Al, Ti, Zr, Sn and Zn in a liquid medium, an oxide from the metal alkoxide is disposed on at least a portion of the surface of the second heat-treated object to which the rare earth phosphate is attached, in an amount of 2% by mass or more and 30% by mass or less relative to the luminescent material.

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