Fluoride phosphor, method for producing the same, and light-emitting apparatus

Abstract

To provide a fluoride phosphor that can improve the reliability of light-emitting devices in high-temperature and high-humidity environments. [Solution] A fluoride phosphor comprising fluoride particles and a phosphate disposed on at least a portion of the surface of the fluoride particles. The phosphate contains at least zinc in its composition. The fluoride particles have a composition comprising element M, which includes at least one selected from the group consisting of group 4 elements, group 13 elements, and group 14 elements, an alkali metal, Mn, and F, wherein, when the number of moles of alkali metal is 2, the number of moles of Mn is greater than 0 and less than 0.2, the number of moles of element M is greater than 0.8 and less than 1, and the number of moles of F is greater than 5 and less than 7.

Description

Technical Field

[0001] The present disclosure relates to a fluoride phosphor, a method for producing the same, and a light-emitting device.

Background Art

[0002] A light-emitting device combining a light-emitting element and a phosphor is used in a wide range of fields such as lighting, vehicle-mounted lighting, displays, and backlights for liquid crystals. For example, for phosphors used in light-emitting devices for backlights for liquid crystals, high color purity, that is, a narrow full width at half maximum of the emission peak, is required. As a phosphor that emits red light with a narrow full width at half maximum of the emission peak, a fluoride phosphor doped with Mn is known.

[0003] For example, Patent Document 1 describes phosphor particles in which inorganic fine particles are attached to the surface of an Mn-doped fluoride red phosphor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a light-emitting device including a fluoride phosphor doped with Mn, when used in a high-temperature and high-humidity environment, the reliability may decrease due to a decrease in luminous flux or the like. One aspect of the present disclosure aims to provide a fluoride phosphor and a method for producing the same that can improve the reliability of a light-emitting device in a high-temperature and high-humidity environment.

Means for Solving the Problems

[0006] The first embodiment is a fluoride phosphor comprising first fluoride particles and a phosphate disposed on at least a portion of the surface of the first fluoride particles. The phosphate contains at least zinc in its composition. The first fluoride particles have a composition comprising element M, which includes at least one selected from the group consisting of group 4 elements, group 13 elements, and group 14 elements, an alkali metal, a manganese ion (Mn), and a fluorine atom (F), wherein, when the number of moles of alkali metal is 2, the number of moles of manganese is greater than 0 and less than 0.2, the number of moles of element M is greater than 0.8 and less than 1, and the number of moles of fluorine atoms is greater than 5 and less than 7.

[0007] The second embodiment is a method for producing a fluoride phosphor, comprising: preparing first fluoride particles having a composition in which, when the number of moles of alkali metal is 2, the number of moles of manganese is greater than 0 and less than 0.2, the number of moles of element M is greater than 0 and less than 1, and the number of moles of fluoride atoms is greater than 5 and less than 7; and contacting at least one metal ion selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and zinc (Zn) with phosphate ions in a liquid medium containing the first fluoride particles to obtain a second fluoride phosphor in which phosphate is attached to the first fluoride particles.

[0008] The third embodiment is a light-emitting device comprising a fluorescent member containing a fluoride phosphor and resin as described in the first embodiment, and a light-emitting element having an emission peak wavelength in the wavelength range of 380 nm to 485 nm. [Effects of the Invention]

[0009] According to one aspect of this disclosure, a fluoride phosphor and a method for producing the same can be provided, which can improve the reliability of light-emitting devices in high-temperature and high-humidity environments. [Brief explanation of the drawing]

[0010] [Figure 1]This is a schematic cross-sectional view showing an example of a light-emitting device containing a fluoride phosphor. [Figure 2A] This is an example of a scanning electron microscope (SEM) image of a fluoride phosphor according to Example 1. [Figure 2B] This is an example of a high-magnification SEM image of a fluoride phosphor according to Example 1. [Figure 3A] This is an example of an SEM image of a fluoride phosphor according to Example 2. [Figure 3B] This is an example of a high-magnification SEM image of a fluoride phosphor according to Example 2. [Figure 4A] This is an example of an SEM image of a fluoride phosphor according to Example 3. [Figure 4B] This is an example of a high-magnification SEM image of a fluoride phosphor according to Example 3. [Figure 5A] This is an example of an SEM image of the fluoride phosphor according to Example 6. [Figure 5B] This is an example of a high-magnification SEM image of a fluoride phosphor according to Example 6. [Figure 6A] This is an example of an SEM image of the fluoride phosphor according to Example 7. [Figure 6B] This is an example of a high-magnification SEM image of a fluoride phosphor according to Example 7. [Figure 7A] This is an example of an SEM image of the fluoride phosphor according to Example 9. [Figure 7B] This is an example of a high-magnification SEM image of a fluoride phosphor according to Example 9. [Modes for carrying out the invention]

[0011] In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as their intended purpose is achieved. Furthermore, the content of each component in a composition refers to the total amount of multiple substances present in the composition, unless otherwise specified, if multiple substances corresponding to each component exist in the composition. In addition, the upper and lower limits of the numerical ranges described herein can be arbitrarily selected and combined from the numerical values ​​exemplified as numerical ranges. In this specification, in formulas representing the composition of a phosphor or luminescent material, multiple elements separated by commas (,) mean that at least one of these multiple elements is contained in the composition. Also, in formulas representing the composition of a phosphor, the element before the colon (:) represents the matrix crystal, and the element after the colon (:) represents the activating element. In this specification, the relationship between color names and chromaticity coordinates, the relationship between the wavelength range of light and the color names of monochromatic light, etc., follow JIS Z8110. The full width at half maximum (FWHM) of a phosphor or light-emitting material refers to the wavelength width (FWHM) of the emission spectrum where the emission intensity is 50% of the maximum emission intensity. Embodiments of the present invention will be described in detail below. However, the embodiments shown below are illustrative of fluoride phosphors, methods for producing the same, and light-emitting devices for realizing the technical concept of the present invention, and the present invention is not limited to the fluoride phosphors, methods for producing the same, and light-emitting devices shown below.

[0012] Fluoride phosphors A fluoride phosphor comprises fluoride particles having a specific composition (hereinafter also referred to as first fluoride particles) and a phosphate salt disposed on at least a portion of the surface of the first fluoride particles. The phosphate salt may contain at least zinc as a metal ion in its composition. The first fluoride particles may contain in their composition an element M, which includes at least one element selected from the group consisting of group 4 elements, group 13 elements, and group 14 elements, an alkali metal, manganese, and a fluorine atom. The composition of the first fluoride particles may be such that, when the number of moles of alkali metal is 2, the number of moles of manganese is greater than 0 and less than 0.2, the number of moles of element M is greater than 0.8 and less than 1, and the number of moles of fluorine atoms is greater than 5 and less than 7.

[0013] The reliability of a light-emitting device containing a fluoride phosphor, particularly in high-temperature and high-humidity environments, can be improved by having a phosphate containing zinc arranged on at least a portion of the surface of first fluoride particles having a specific composition. This can be considered, for example, as follows: In a light-emitting device formed by encapsulating a light-emitting element with a resin containing a fluoride phosphor, the arrangement of phosphate on at least a portion of the surface of the first fluoride particles constituting the fluoride phosphor reduces the contact area between the resin and the first fluoride particles. This suppresses the reaction between the resin and the first fluoride particles under high-temperature and high-humidity conditions, thereby suppressing resin degradation, preventing or reducing luminous flux reduction, and improving the reliability of the light-emitting device. Furthermore, by including zinc ions as metal ions in the phosphate, the phosphate can be more uniformly arranged, which can more effectively improve the reliability of the light-emitting device.

[0014] The first fluoride particles constituting the fluoride phosphor may contain at least a phosphor activated by manganese (Mn), and may consist solely of a phosphor activated by manganese (Mn). The composition of the first fluoride particles may be such that, when the number of moles of alkali metal is 2, the number of moles of manganese is greater than 0 and less than 0.2, preferably between 0.01 and 0.12. The composition of the first fluoride particles may also be such that, when the number of moles of alkali metal is 2, the number of moles of element M is greater than 0.8 and less than 1, preferably between 0.88 and 0.99. The composition of the first fluoride particles may also be such that, when the number of moles of alkali metal is 2, the number of moles of fluorine atoms is greater than 5 and less than 7, preferably between 5.9 and 6.1. The composition of the first fluoride particles can be measured, for example, by inductively coupled plasma (ICP) emission spectroscopy.

[0015] The alkali metal in the composition of the first fluoride particles may include at least one selected from the group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs). Alternatively, the alkali metal may include at least potassium (K) and at least one selected from the group consisting of lithium (Li), sodium (Na), rubidium (Rb), and cesium (Cs). The ratio of moles of K to the total number of moles of alkali metals in the composition may be, for example, 0.90 or higher, preferably 0.95 or higher, or 0.97 or higher. The upper limit of the ratio of moles of K may be, for example, 1 or 0.995 or lower. In the composition of the first fluoride particles, a portion of the alkali metal may be ammonium ions (NH4). + ) may be substituted with ammonium ions. When some of the alkali metals are substituted with ammonium ions, the ratio of the number of moles of ammonium ions to the total number of moles of alkali metals in the composition may be, for example, 0.10 or less, preferably 0.05 or less, or 0.03 or less. The lower limit of the ratio of moles of ammonium ions may be, for example, greater than 0, preferably 0.005 or more.

[0016] The element M in the composition of the first fluoride particles includes at least one selected from the group consisting of Group 4 elements, Group 13 elements, and Group 14 elements. Examples of Group 4 elements include titanium (Ti), zirconium (Zr), hafnium (Hf), etc., and at least one selected from the group consisting of these elements may be included. Examples of Group 13 elements include boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), etc., and at least one selected from the group consisting of these elements may be included. Examples of Group 14 elements include carbon (C), silicon (Si), germanium (Ge), tin (Sn), etc., and at least one selected from the group consisting of these elements may be included. Element M may include at least one of the Group 14 elements, preferably at least one of Si and Ge, and more preferably at least Si. Furthermore, element M may include at least one element from group 13 and at least one element from group 14, preferably at least Al and at least one of Si and Ge, and more preferably at least Al and Si.

[0017] One embodiment of the composition of the first fluoride particles is a first composition which may contain at least one element M selected from the group consisting of group 4 elements and group 14 elements, preferably at least one selected from the group consisting of group 14 elements, more preferably at least one of Si and Ge, and even more preferably at least Si. In addition, the first composition of the first fluoride particles may have a total number of moles of Si, Ge and Mn of 0.9 to 1.1 per 2 moles of alkali metal, preferably 0.95 to 1.05, or 0.97 to 1.03.

[0018] The first composition of the first fluoride particles may be the composition represented by the following formula (1). A 1 c [M 1 1-b Mn b F d(1)

[0019] In formula (1), A 1 may contain at least one selected from the group consisting of Li, Na, K, Rb, and Cs. M 1 contains at least one of Si and Ge, and may further contain at least one element selected from the group consisting of Group 4 elements and Group 14 elements. Mn may be tetravalent Mn ions. b satisfies 0 < b < 0.2, and c is [M 1 1-b Mn b F d the absolute value of the charge of the ion, and d satisfies 5 < d < 7.

[0020] A in formula (1) 1 contains at least K, and may further contain at least one selected from the group consisting of Li, Na, Rb, and Cs. Also, A 1 may have a part thereof substituted with ammonium ions (NH4 + ). When a part of A 1 is substituted with ammonium ions, the ratio of the number of moles of ammonium ions to the total number of moles of A 1 in the composition may 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 may be, for example, more than 0, preferably 0.005 or more.

[0021] b in formula (1) 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. c may be, for example, 1.8 or more and 2.2 or less, preferably 1.9 or more and 2.1 or less, or 1.95 or more and 2.05 or less. d is preferably 5.5 or more and 6.5 or less, 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.

[0022] Furthermore, the first fluoride particles of the first composition may have a first theoretical composition represented by the following formula (1a). A 1 2M1 F6:Mn (1a)

[0023] In formula (1a), A 1 This may include at least one element selected from the group consisting of Li, Na, K, Rb, and Cs. 1 It comprises at least one of Si and Ge, and may further comprise at least one element selected from the group consisting of Group 4 and Group 14 elements. Mn may be a tetravalent Mn ion.

[0024] A second composition, which is one embodiment of the composition of the first fluoride particles, may contain at least one element M selected from the group consisting of Group 4 and Group 14 elements, and at least one element from Group 13, preferably at least one element selected from the group consisting of Group 14 elements, and at least one element from Group 13, and more preferably at least Si and Al. Furthermore, in the second composition of the first fluoride particles, the total number of moles of Si, Al and Mn per 2 moles of alkali metal may be 0.9 to 1.1, preferably 0.95 to 1.05, or 0.97 to 1.03. Moreover, in the second composition of the first fluoride particles, the number of moles of Al per 2 moles of alkali metal may be greater than 0 and 0.1, preferably greater than 0 and 0.03, 0.002 to 0.02, or 0.003 to 0.015.

[0025] The second composition of the first fluoride particles may be the composition represented by the following formula (2). A 2 f [M 2 1-e Mn e F g (2)

[0026] In formula (2), A 2 It contains at least K and may further contain at least one selected from the group consisting of Li, Na, Rb, and Cs. 2contains at least Si and Al, and may further contain at least one element selected from the group consisting of Group 4 elements, Group 13 elements, and Group 14 elements. Mn may be tetravalent Mn ions. e satisfies 0 < e < 0.2, and f is 2 1-e Mn e F g the absolute value of the charge of the ] ion, and g satisfies 5 < g < 7.

[0027] A in formula (2) 2 may be partially substituted with ammonium ions (NH4 + ). When a part of A 2 is substituted with ammonium ions, the ratio of the number of moles of ammonium ions to the total number of moles of A 2 in the composition may 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 may be, for example, more than 0, preferably 0.005 or more.

[0028] In formula (2), e 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. f may be, for example, 1.8 or more and 2.2 or less, preferably 1.9 or more and 2.1 or less, or 1.95 or more and 2.05 or less. g is preferably 5.5 or more and 6.5 or less, 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.

[0029] Furthermore, the first fluoride particles of the second composition may have a second theoretical composition represented by the following formula (2a). A 2 2Si 1-p Al p F 6-p :Mn (2a)

[0030] In formula (2a), A 2It may contain at least K and may further contain at least one selected from the group consisting of Li, Na, Rb, and Cs. p satisfies 0 < p < 1. Mn may be tetravalent Mn ions.

[0031] The first fluoride particles having the second composition may have 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 a powder composed of the first fluoride particles. The angle of repose of a powder composed of the first fluoride particles having the second composition may be, for example, 70° or less, preferably 65° or less, or 60° or less. The lower limit of the angle of repose is, for example, 30° or more. The angle of repose is measured, for example, by the pouring method.

[0032] When the first fluoride particles having the second composition have irregularities, grooves, etc. on the surface, for example, when arranging a phosphate on the surface of the first fluoride particles, the contact area between the first fluoride particles and the phosphate increases. Therefore, a strong bond can be obtained between the first fluoride particles and the phosphate, and the phosphate can be arranged on the surface of the first fluoride particles in a state where it is difficult to be peeled off by an external force. Also, even when a relatively small amount of phosphate raw material is used, it is possible to arrange a sufficient amount of phosphate on the surface of the first fluoride particles. Similarly, when the surface of the first fluoride particles is covered with a specific oxide, or when the oxide covers the first fluoride particles via a phosphate, since the first fluoride phosphor has irregularities, grooves, etc. on the surface, when covering the first fluoride particles with a specific oxide, the contact area between the first fluoride particles and the oxide increases. Therefore, the bond between the first fluoride particles and the oxide becomes stronger, and the first fluoride particles can be covered with an oxide film that is difficult to be peeled off by an external force during the manufacture of the light-emitting device. Also, even when a relatively small amount of oxide raw material is used, it is possible to cover the first fluoride particles with a sufficient amount of oxide.

[0033] The volume-based median diameter of the first fluoride particles may be, for example, 5 μm to 90 μm, preferably 10 μm to 70 μm, or 15 μm to 50 μm, from the viewpoint of improving brightness. The particle size distribution of the first fluoride particles may, for example, show a single-peak particle size distribution, preferably a single-peak particle size distribution with a narrow distribution width, from the viewpoint of improving brightness. Specifically, in the volume-based particle size distribution, if D10 is the particle size corresponding to 10% of the volume accumulation from the small diameter side, and D90 is the particle size corresponding to 90% of the volume accumulation, then the ratio of D90 to D10 (D90 / D10) may be, for example, 3.0 or less. The volume-based median diameter is the particle size corresponding to 50% of the volume accumulation from the small diameter side in the volume-based particle size distribution, and the volume-based particle size distribution is measured by a laser diffraction particle size distribution analyzer.

[0034] The first fluoride particle may have a surface region with a lower manganese concentration than the internal region. The first fluoride particle is a phosphor activated by manganese ions, and it is thought that in the surface region of the particle, the manganese ions constituting the first fluoride particle react with moisture in the external environment to generate manganese dioxide, resulting in the particle surface becoming black, which in turn reduces the luminescence output and causes a shift in chromaticity. However, by keeping the manganese concentration in the surface region of the first fluoride particle lower than that in the internal region, the generation of manganese dioxide on the particle surface is suppressed, which is thought to suppress the decrease in luminescence output and the shift in chromaticity over a long period of time, thereby improving the reliability of the light-emitting device.

[0035] The surface region may be separated from the interior region by a clear interface, such as a two-layer structure, or it may not be separated from the interior region by a clear interface, and the manganese concentration may gradually decrease from the inside to the outside of the surface region. The average value of the manganese concentration present in the surface region of the first fluoride particles may be, for example, 30% by mass or less, preferably 25% by mass or less, or 20% by mass or less, relative to the average value of the manganese concentration in the interior region. The manganese concentration in the surface region may be, for example, 0.5% by mass or more of the interior region. The thickness of the surface region depends on the particle size of the fluoride phosphor, but may be, for example, about 1 / 10 to 1 / 50 of the average particle size. Specifically, for example, if the average particle size of the first fluoride particles is 20 μm or more and 40 μm or less, the thickness of the surface region may be, for example, 2 μm or less. First fluoride particles having a surface region with a lower manganese concentration than the manganese concentration in the interior region can be manufactured, for example, by referring to the manufacturing method described in Japanese Patent Application Publication No. 2015-042705.

[0036] The fluoride phosphor may contain phosphate (metal phosphate) arranged on at least a portion of the surface of the first fluoride particles. The shape of the phosphate arranged on the surface of the first fluoride particles may be particulate or film-like. Here, having a particulate shape means that the individual shapes of the arranged phosphates are similar, and the outer edge of one phosphate can be distinguished from the outer edge of another. The shape of the phosphate may be, for example, spherical or rod-shaped. A film-like shape means that the outer edges of individual phosphates are irregular in shape. The shape of the phosphate may preferably be film-like. By arranging the phosphate in a film-like manner on the surface of the first fluoride particles, the surface of the first fluoride particles can be more uniformly coated. The coating rate of the first fluoride particles by phosphate in the fluoride phosphor may be, for example, 50% or more, preferably 80% or more, or 90% or more. The coverage rate of the first fluoride particles by phosphate is calculated as the ratio of the area covered by phosphate to the surface area of ​​the first fluoride particles.

[0037] The phosphate, which is positioned on at least a portion of the surface of the first fluoride particles, may contain at least zinc (Zn) ions as metal ions. That is, the phosphate may contain at least zinc phosphate (e.g., Zn3(PO4)2). The presence of zinc ions in the phosphate tends to make it easier to adhere more uniformly to the surface of the first fluoride particles.

[0038] The phosphate may contain metal ions other than zinc ions. Examples of metal ions other than zinc ions include magnesium (Mg) ions, calcium (Ca) ions, and strontium (Sr) ions. The phosphate may contain at least zinc ions and further contain at least one metal ion selected from the group consisting of magnesium ions, calcium ions, and strontium ions. The phosphate disposed on at least a portion of the surface of the first fluoride particles may be only one type or a combination of two or more types.

[0039] When the phosphate contains zinc ions, the ratio of the number of moles of zinc ions to the total number of moles of metal ions in the phosphate may be, for example, 60 mol% or more, preferably 80 mol% or more, and may be 100 mol% or less. When the phosphate contains metal ions other than zinc ions, the ratio of the number of moles of metal ions other than zinc ions to the total number of moles of metal ions in the phosphate may be, for example, 60 mol% or less, preferably 40 mol% or less, or 20 mol% or less, and may be 10 mol% or more. In one embodiment, the phosphate may be substantially zinc phosphate. Here, "substantially" means that metal ions other than zinc ions that are inevitably mixed in are not excluded. Specifically, this means that the ratio of the number of moles of metal ions other than zinc ions to the total number of moles of metal ions in the phosphate is 5 mol% or less, or 1 mol% or less.

[0040] The phosphate content in the fluoride phosphor may be, for example, 0.01% by mass or more, preferably 0.1% by mass or more, or 0.2% by mass or more, and may be 5% by mass or less, or 2% by mass or less, in terms of zinc relative to the fluoride phosphor. When the phosphate content is within the above range, the reliability of the light-emitting device tends to be improved more effectively. The phosphate content in the fluoride phosphor can be calculated by inductively coupled plasma (ICP) emission spectroscopy.

[0041] The fluoride phosphor may further contain an oxide disposed on at least a portion of the surface of the first fluoride particles. The oxide may coat at least a portion of the surface of the first fluoride particles. The oxide may be directly disposed on the surface of the first fluoride particles and coat them, or it may coat the first fluoride particles via a phosphate disposed on the surface of the first fluoride particles. The oxide may also, for example, coat the surface of the first fluoride particles in a film-like manner, or it may be disposed on the surface of the first fluoride particles as an oxide layer. The oxide film covering the surface of the first fluoride particles is not limited to a state in which there are no cracks at all, and cracks may be present in a portion of the oxide film covering the surface of the first fluoride particles to the extent that the effects of the invention are obtained. Although it is preferable that the oxide film covering the surface of the first fluoride particles completely covers the entire surface, a portion of the oxide film may be missing, and a portion of the surface of the first fluoride particles may be exposed to the extent that the effects are obtained. The oxide coverage rate of the first fluoride particles in the fluoride phosphor may be, for example, 50% or more, preferably 80% or more, or 90% or more. The oxide coverage rate of the first fluoride particles is calculated as the ratio of the area covered by the oxide to the surface area of ​​the first fluoride particles.

[0042] The oxide may contain at least one selected from the group consisting of silicon (Si), aluminum (Al), titanium (Ti), zirconium (Zr), tin (Sn), and zinc (Zn). That is, the oxide may contain at least one selected from the group consisting of silicon oxide (e.g., SiOx, where x is 1 or more and 2 or less, preferably 1.5 or more and 2 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 consist of only one type, or it may contain two or more types.

[0043] The oxide content in the fluoride phosphor may be 2% by mass or more and 30% by mass or less relative to the fluoride phosphor, preferably 5% by mass or more and 20% by mass or 8% by mass or more and 15% by mass or less. For example, when the oxide is silicon oxide, the oxide content in the fluoride phosphor is determined by inductively coupled plasma (ICP) emission spectroscopy, where the amounts of each constituent element in oxide-covered fluoride particles and oxide-free fluoride particles are analyzed, and the molar ratio of each constituent element is calculated such that the number of moles of alkali metal is 2. The difference in the molar ratio of silicon before and after oxide coating is converted to the mass of silicon oxide (e.g., SiO2), and the silicon oxide (e.g., SiO2) content is calculated by setting the mass of the oxide-covered first fluoride particles (fluoride phosphor) to 100% by mass. Having the oxide content within the above range can further improve the reliability of the light-emitting device.

[0044] In fluoride phosphors, the first fluoride particles may be covered with an oxide layer. The average thickness of the oxide layer covering the first fluoride particles may be, for example, 20 nm to 800 nm, preferably 100 nm or more, or 200 nm or more, and 700 nm or less, or 500 nm or less. The average thickness of the oxide layer in the first fluoride phosphor may be, for example, the measured average thickness obtained by measuring the thickness of the layer identified as the oxide layer at several locations in a cross-sectional image of the fluoride phosphor and taking the arithmetic mean. Alternatively, the average thickness of the oxide layer in the fluoride phosphor may be the theoretical thickness calculated from 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 from the ratio of the peak intensity of the Kα-ray of element F in the first fluoride phosphor covered with an oxide layer to the peak intensity of the Kα-ray of element F in the first fluoride phosphor covered with an oxide layer. The theoretical thickness is calculated as an average value that takes into account the presence of defects such as cracks and chips in the oxide layer.

[0045] In fluoride phosphors containing oxides, the peak intensity of characteristic X-rays originating from the first fluoride particles decreases in proportion to the amount of oxide covering the first fluoride particles, because the first fluoride particles are covered with oxide. Therefore, in fluoride phosphors, the oxide coating state can be evaluated by evaluating the peak intensity of characteristic X-rays originating from the first fluoride particles. Specifically, in X-ray fluorescence (XRF) elemental analysis, the ratio of the peak intensity of the Kα line of element F in the fluoride phosphor to the peak intensity of the Kα line of element F in the first fluoride particles may be, for example, 80% or less, preferably 70% or less, or 60% or less. The lower limit of the peak intensity ratio may be, for example, 20% or more. By keeping the ratio of the peak intensity of the Kα line of element F in the fluoride phosphor within the above range, the reliability of the light-emitting device can be more effectively improved.

[0046] The surface of the fluoride phosphor may be treated with a coupling agent. That is, a surface treatment layer containing functional groups derived from the coupling agent may be arranged on the surface of the fluoride phosphor. By arranging a surface treatment layer on the surface of the fluoride phosphor, for example, the moisture resistance of the fluoride phosphor is further improved.

[0047] Examples of functional groups derived from the coupling agent include silyl groups having an aliphatic group with 1 to 20 carbon atoms, and preferably silyl groups having an aliphatic group with 6 to 12 carbon atoms. The functional groups derived from the coupling agent may be a single type or a combination of two or more types.

[0048] Examples of coupling agents include silane coupling agents, titanium coupling agents, and aluminum coupling agents. Examples of silane coupling agents include alkyltrialkoxysilanes such as methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, and decyltriethylsilane; aryltrialkoxysilanes such as phenyltrimethoxysilane and styryltrimethoxysilane; vinyltrialkoxysilanes such as vinyltrimethoxysilane; aminoalkyltrialkoxysilanes such as 3-aminopropyltriethoxysilane; and glycidoxyalkyltrialkoxysilanes such as 3-glycidoxypropyltrimethoxysilane. At least one of these may be selected from the group. Silane coupling agents are preferred as coupling agents because they are relatively easy to obtain.

[0049] The volume-based median diameter of the fluoride phosphor may be, for example, 10 μm to 90 μm, preferably 15 μm to 70 μm, or 20 μm to 50 μm, from the viewpoint of improving brightness. The particle size distribution of the fluoride phosphor may, for example, show a single-peak particle size distribution, preferably a single-peak particle size distribution with a narrow distribution width, from the viewpoint of improving brightness. Specifically, in the volume-based particle size distribution, the ratio of D90 to D10 (D90 / D10) may be, for example, 3.0 or less.

[0050] A fluoride phosphor is, for example, a phosphor activated with tetravalent manganese ions, which absorbs light in the short-wavelength region of the visible light and emits red light. The excitation light may be mainly in the blue region, and the peak wavelength of the excitation light may be, for example, in the wavelength range of 380 nm to 485 nm. The emission peak wavelength in the emission spectrum of the fluoride phosphor may be, for example, in the wavelength range of 610 nm to 650 nm. The full width at half maximum in the emission spectrum of the fluoride phosphor may be, for example, 10 nm or less.

[0051] Method for producing fluoride phosphors A method for producing a fluoride phosphor may include a preparation step of preparing first fluoride particles having a specific composition, and a phosphate deposition step of contacting the first fluoride particles with at least one metal ion selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and zinc (Zn) and a phosphate ion in a liquid medium to obtain a second fluoride phosphor in which phosphate is attached to the first fluoride particles, and may further include other steps as needed. The first fluoride particles may contain in their composition an element M including at least one selected from the group consisting of group 4 elements, group 13 elements, and group 14 elements, an alkali metal, manganese, and a fluorine atom, and when the number of moles of alkali metal is 2, the number of moles of manganese may be greater than 0 and less than 0.2, the number of moles of element M may be greater than 0.8 and less than 1, and the number of moles of fluorine atoms may be greater than 5 and less than 7.

[0052] By bringing specific metal ions and phosphate ions into contact with first fluoride particles in a liquid medium, metal phosphates containing the specific metal ions precipitate on at least a portion of the surface of the first fluoride particles, thereby obtaining a second fluoride phosphor with metal phosphates attached to the surface of the first fluoride particles. A light-emitting device constructed using the obtained second fluoride particles can have improved reliability in high-temperature and high-humidity environments.

[0053] In the preparation step, first fluoride particles having a predetermined composition are prepared. In the preparation step, the first fluoride particles may be obtained by acquisition or other means, or the desired first fluoride particles may be manufactured. Details of the first fluoride particles to be prepared are as previously described.

[0054] The first fluoride particles can be produced, for example, as follows. If the first fluoride particles have a first composition, they can be produced by a manufacturing method that includes mixing solution a, which contains at least a first complex ion including tetravalent manganese, at least one selected from the group consisting of group 4 and group 14 elements, a second complex ion including a fluoride ion, and hydrogen fluoride, with solution b, which contains at least an alkali metal including potassium and at least hydrogen fluoride.

[0055] Furthermore, it can also be produced by a manufacturing method that includes, for example, mixing a first solution containing at least a first complex ion including tetravalent manganese and hydrogen fluoride, a second solution containing at least an alkali metal including at least potassium and hydrogen fluoride, and a third solution containing at least one element selected from the group consisting of group 4 and group 14 elements and a second complex ion containing fluoride ions. For a method of producing first fluoride particles having the first composition, see, for example, Japanese Patent Application Publication No. 2015-044973.

[0056] If the first fluoride particles have a second composition, the first fluoride particles having the second composition can be produced by a method that includes, for example, preparing fluoride particles having the first composition, preparing a composite fluoride containing Al, an alkali metal, and F, and performing a first heat treatment step in which the mixture containing this composite fluoride and the fluoride particles having the first composition is subjected to a first heat treatment at a first heat treatment temperature of 600°C to 780°C in an inert gas atmosphere. Here, the composition of the composite fluoride containing Al, an alkali metal, and F may be such that the ratio of the total number of moles of alkali metal to the number of moles of Al is 1 or more and 3 or less, and the ratio of the number of moles of F is 4 or more and 6 or less. Alternatively, the ratio of the total number of moles of alkali metal to the number of moles of Al is 2 or more and 3 or less, and the ratio of the number of moles of F is 5 or more and 6 or less.

[0057] The method for producing the first fluoride particles may further include a second heat treatment step, in which the first heat-treated product obtained after the first heat treatment is subjected to a second heat treatment at a second heat treatment temperature of 400°C or higher to obtain a second heat-treated product.

[0058] The second heat treatment step may be performed using only the first fluoride particles obtained in the first heat treatment, or it may be performed by bringing the first fluoride particles into contact with a fluorine-containing substance. This fluorine-containing substance may be in a solid, liquid, or gaseous state at room temperature. Examples of fluorine-containing substances in a solid or liquid state include NH4F. Examples of fluorine-containing substances in a gaseous state include F2, CHF3, CF4, NH4HF2, HF, SiF4, KrF4, XeF2, XeF4, NF3, etc., and may be at least one selected from the group consisting of these, preferably at least one selected from the group consisting of F2 and HF.

[0059] The second heat treatment temperature is preferably higher than 400°C, may be 425°C or higher, 450°C or higher, or 480°C or higher. The upper limit of the second heat treatment temperature may be, for example, less than 600°C, preferably 580°C or lower, 550°C or lower, or 520°C or lower. The second heat treatment temperature may be lower than the first heat treatment temperature.

[0060] The first fluoride particles of the second composition, synthesized by the solid-phase reaction method in the first heat treatment step, are thought to contain a compound with mixed valence, so to speak, because tetravalent Si ions, trivalent Al ions, and tetravalent Mn ions are present at the same positions within the crystal of the first fluoride particles. Consequently, it is thought that vacancies exist at the positions where fluoride ions should be located in the crystal, proportional to the abundance ratio of tetravalent Si ions, trivalent Al ions, and tetravalent Mn ions, in order to compensate for the overall charge deficiency of the mixed-valence cations.

[0061] Here, for example, in the first fluoride particles synthesized by a liquid-phase reaction method, as disclosed in Japanese Patent Publication No. 2010-254933, numerous hydroxide ions introduced into the crystal from hydroxide ions present in the solution are mixed with the fluoride ions at the positions where fluoride ions should be located in the crystal. It is thought that these hydroxide ions are the cause of the instability of the first fluoride particles. On the other hand, in the second composition of first fluoride particles synthesized by a solid-phase reaction method using heat treatment, no solution in which hydroxide ions may be present is used, so hydroxide ions that cause the instability of the first fluoride particles are not present.

[0062] Furthermore, the first fluoride particles of the second composition, synthesized by a solid-phase reaction method in the first heat treatment step, may contain Mn ions with different valencies in the crystal structure or on the crystal surface of the fluoride particles. When Mn ions with different valencies are present in the fluoride particles, it is possible to further heat-treat them in contact with a fluorine-containing material to unify the valence of the Mn ions to a tetravalent state, thereby increasing the luminescence efficiency of the first fluoride particles. For a method of producing the first fluoride particles having the second composition, see, for example, Japanese Patent Application Publication No. 2022-099232.

[0063] The preparation step may further include a modification step in which a surface region with a lower manganese concentration than the internal region is formed on the first fluoride particles. By having a surface region with a lower manganese concentration on the first fluoride particles, the formation of manganese dioxide on the particle surface is suppressed, which suppresses the decrease in luminescence output and chromaticity shift over a long period of time, and further improves the reliability of the light-emitting device.

[0064] The modification step may include a reduction step in which first fluoride particles are brought into contact with a reducing agent, and a surface region formation step in which, in the presence of hydrogen fluoride, the first fluoride particles that have been brought into contact with the reducing agent are brought into contact with a second complex ion containing at least one element selected from the group consisting of Group 4 and Group 14 elements and a fluoride ion, and a cation containing at least an alkali metal including potassium. Examples of reducing agents include hydrogen peroxide and oxalic acid. For a method of producing first fluoride particles having a surface region with a manganese concentration lower than that of the internal region, refer to Japanese Patent Application Publication No. 2023-058411.

[0065] The preparation step may further include a pressurized heating step in which the first fluoride particles are pressurized and heated in a liquid medium. By pressurizing and heating the fluoride particles in a liquid medium, first fluoride particles with superior luminescence brightness and durability can be obtained. The first fluoride particles obtained by pressurizing and heating have a higher reflectivity at a wavelength of 510 nm, for example, and when applied to lighting applications together with a green-emitting phosphor, the decrease in brightness in the green region can be suppressed more effectively.

[0066] In the pressurized heating process, a mixture containing first fluoride particles and a liquid medium is subjected to pressurized and heated treatment. Treatment in a liquid medium allows for a more uniform treatment effect on the first fluoride particles. The composition of the liquid medium is not particularly limited and can be appropriately selected from commonly used liquids depending on the purpose. Specific examples of liquid mediums include water; alcohol solvents such as methanol, ethanol, and isopropyl alcohol; ketone solvents such as acetone and methyl ethyl ketone; and organic solvents such as diethyl ether and diisopropyl ether. The liquid medium may also be a substance that is a gas at normal pressure but liquefies under pressure, or a substance that is a solid at room temperature but liquefies under heat. Preferably, the liquid medium contains at least water. The liquid medium may be used alone or in combination of two or more types.

[0067] The liquid medium may further contain components that are soluble in the liquid medium. Examples of components that are soluble in the liquid medium include inorganic acids such as hydrogen fluoride (HF), hexafluorosilicic acid (H2SiF6), and nitric acid (HNO3); peroxides such as hydrogen peroxide; and inorganic salts containing potassium ions such as potassium hydrogen fluoride (KHF2), potassium nitrate (KNO3), and potassium fluoride (KF). In particular, the liquid medium preferably contains at least potassium ions, and more preferably contains at least an inorganic salt containing potassium ions. When the liquid medium contains potassium ions, the concentration of potassium ions can be, for example, 5% by mass or more and 10% by mass or less. The components that are soluble in the liquid medium may be used individually or in combination of two or more.

[0068] The amount of liquid medium used is not particularly limited and can be appropriately selected depending on the processing method, etc. For example, the amount of liquid medium used may be 100 parts by mass or more and 160 parts by mass or less per 100 parts by mass of first fluoride particles, preferably 130 parts by mass or more and 160 parts by mass or less.

[0069] From the viewpoint of improving durability, the pressure conditions for pressurization treatment may be calculated to be, for example, 1.5 MPa or higher, preferably 2.5 MPa or higher, or 5.0 MPa or higher. Also, from the viewpoint of durability and manufacturing efficiency, the pressure conditions may be, for example, 30 MPa or lower, preferably 15 MPa or lower. The pressurization treatment time may be appropriately selected according to the treatment conditions such as pressure. From the viewpoint of improving durability, the treatment time may be, for example, 4 hours or more, preferably 6 hours or more, or 8 hours or more. From the viewpoint of durability and manufacturing efficiency, the treatment time may be, for example, 48 hours or less, preferably 24 hours or less, or 20 hours or less.

[0070] The pressurized treatment can be carried out by placing the above mixture in a pressure-resistant sealed container, such as an autoclave, and applying pressure. The pressurization method is not particularly limited and can be appropriately selected from commonly used pressurization methods. Specifically, for example, the pressurized treatment may be carried out by reducing the volume of the pressure-resistant sealed container, by injecting a gas such as air or an inert gas, or by heating while maintaining a sealed state to apply pressure using the vapor pressure of the liquid medium. The atmosphere during the pressurized treatment is not particularly limited and may be an atmospheric atmosphere or an inert gas atmosphere.

[0071] From the viewpoint of improving durability, the heat treatment temperature may 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 heat treatment temperature may be, for example, 300°C or lower, preferably 200°C or lower. The heat treatment time may be appropriately selected according to the treatment conditions such as temperature. From the viewpoint of improving durability, the heat treatment time may be, for example, 4 hours or more, preferably 8 hours or more. From the viewpoint of durability and manufacturing efficiency, the heat treatment time may be, for example, 24 hours or less, preferably 20 hours or less. The atmosphere during the heat treatment is not particularly limited and may be an air atmosphere or an inert gas atmosphere.

[0072] In the pressurized heating process, the pressurizing treatment and the heating treatment may be performed sequentially, or they may overlap in terms of time. When the pressurizing treatment and the heating treatment overlap in terms of time, for example, the mixture can be placed in a pressure-resistant sealed container and heated, thereby pressurizing the mixture using the vapor pressure of the liquid medium. The pressurized heating process is preferably performed at a heating temperature of 120°C to 300°C and a pressure of 2.5 MPa to 30 MPa for 8 hours to 48 hours, and more preferably at a temperature of 150°C to 200°C and a pressure of 5.0 MPa to 12 MPa for 6 hours to 24 hours. For the pressurized heating process for the first fluoride particles, refer to, for example, the description in Japanese Patent Application Publication No. 2015-199877.

[0073] The preparation steps may further include steps such as recovering the obtained first fluoride phosphor by solid-liquid separation and drying the solid-liquid separated fluoride phosphor.

[0074] In the phosphate deposition process, the prepared first fluoride particles are brought into contact with phosphate ions and at least one metal ion selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and zinc (Zn) in a liquid medium. As a result, phosphate containing the specific metal ion adheres to the surface of the fluoride particles, yielding second fluoride particles with the metal phosphate attached. It is believed that depositing the metal phosphate onto the first fluoride particles in a liquid medium allows the metal phosphate to adhere more uniformly, for example, to the surface of the first fluoride particles.

[0075] The liquid medium only needs to be capable of dissolving phosphate ions and metal ions, and it is preferable that it contains at least water, as these ions dissolve easily. The liquid medium may further contain, as needed, a reducing agent such as hydrogen peroxide, an organic solvent, a pH adjuster, etc. Examples of organic solvents that the liquid medium may contain include alcohol solvents such as ethanol and isopropanol. Examples of pH adjusters include basic 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 may be, for example, 3 to 9, preferably 4 to 8, or 5 to 7. A pH above the lower limit tends to result in a sufficient amount of metal phosphate deposition, while a pH below the upper limit tends to suppress the decrease in the luminescence properties of the second fluoride phosphor. The pH is measured at 2°C. 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.

[0076] The mass ratio of the liquid medium to the first fluoride particles may be, for example, 100% by mass or more, or 200% by mass or more, or for example, 1000% by mass or less, or 800% by mass or less. When the mass ratio of the liquid medium is above the lower limit, it becomes easier to uniformly adhere the metal phosphate to the surface of the first fluoride particles, and when the mass ratio of the liquid medium is below the upper limit, the adhesion rate of the metal phosphate to the first fluoride particles tends to improve further.

[0077] The liquid medium preferably contains phosphate ions, and more preferably contains water and phosphate ions. When the liquid medium contains phosphate ions, the prepared first fluoride particles and the liquid medium are mixed, and then mixed with a solution containing specific metal ions, thereby bringing the phosphate ions and metal ions into contact in the liquid medium containing the first fluoride particles. When the liquid medium contains phosphate ions, the phosphate ion concentration 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 phosphate ion concentration in the liquid medium is above the above lower limit, the amount of liquid medium does not become too large, the elution of compositional components from the first fluoride particles is suppressed, and the properties of the second fluoride phosphor tend to be well maintained. When it is below the above upper limit, the uniformity of the deposits on the first fluoride particles tends to be good.

[0078] Phosphate ions include orthophosphate ions, polyphosphate (metaphosphate) ions, phosphite ions, and hypophosphate ions. Polyphosphate ions include linear polyphosphate ions such as pyrophosphate ions and tripolyphosphate ions, and cyclic polyphosphate ions such as hexametaphosphate.

[0079] If the liquid medium contains phosphate ions, it may be prepared by dissolving a compound that serves as a phosphate ion source in the liquid medium, or by mixing a solution containing a 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.

[0080] The liquid medium may contain a reducing agent, preferably water and a reducing agent, and more preferably water, phosphate ions and a reducing agent. The presence of a reducing agent in the liquid medium effectively suppresses the precipitation of manganese dioxide and other substances derived from manganese contained in the first fluoride particles. The reducing agent in the liquid medium should be capable of reducing, for example, tetravalent manganese ions that elute from the first fluoride particles into the liquid medium. Examples of reducing agents include hydrogen peroxide, oxalic acid, and hydroxyamine hydrochloride. Of these, hydrogen peroxide is preferred because it decomposes in water and therefore does not adversely affect the second fluoride particles.

[0081] If the liquid medium contains a reducing agent, it may be prepared by dissolving the reducing agent compound in the liquid medium, or by mixing the solution containing the reducing agent with the liquid medium. The content of the reducing agent in the liquid medium is not particularly limited, but for the reasons mentioned above, it is preferably 0.1% by mass or more, and preferably 0.3% by mass or more.

[0082] The metal element to be brought into contact with the phosphate ion is preferably at least one selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and zinc (Zn), and more preferably contains at least zinc. The ratio of the number of moles of zinc ions to the total number of moles of metal ions brought into contact with the phosphate ion may be, for example, 40 mol% or more, preferably 60 mol% or more, or 80 mol% or more, and may be 100 mol% or less, or 90 mol or less. If the metal ions brought into contact with the phosphate ion include metal ions other than zinc ions, the ratio of the number of moles of metal ions other than zinc ions to the total number of moles of metal ions may be, for example, 60 mol% or less, preferably 40 mol% or less, or 20 mol% or less, and may be 10 mol% or more.

[0083] Contact between phosphate ions and metal ions in a liquid medium may be carried out, for example, by dissolving a compound that serves as a metal ion source in a liquid medium containing phosphate ions, or by mixing a liquid medium containing phosphate ions with a solution containing metal ions. A solution containing metal ions can be prepared, for example, by dissolving a compound that serves as a metal ion source in a solvent such as water. A compound that serves as a metal ion source is, for example, a metal salt containing a specific metal element, and examples of anions constituting the metal salt include nitrate ions, sulfate ions, acetate ions, chloride ions, etc.

[0084] Contact between phosphate ions and metal ions in a liquid medium can include, for example, mixing a liquid medium containing phosphate ions, preferably further containing a reducing agent, with first fluoride particles to obtain a phosphor slurry, or mixing the phosphor slurry with a solution containing metal ions. Mixing the phosphor slurry with the solution containing metal ions may be carried out by adding the solution containing metal ions to the phosphor slurry. The time required for adding the solution containing metal ions may be, for example, 30 seconds to 4 hours, preferably 1 hour or more and 3 hours or less. When adding a solution containing metal ions to a phosphor slurry, the pH of the phosphor slurry may change with the addition of the solution containing metal ions. The change in pH may be, for example, a decrease in pH. The range of the pH change may be, for example, 3 to 9, preferably 5 or more, or 7 or less.

[0085] The metal ion content in a solution containing metal ions may be, for example, 0.05% by mass or more, or 0.1% by mass or more, or for example, 3% by mass or less, or 2% by mass or less. The metal ion content relative to the amount of fluoride particles in the liquid medium may be, for example, 0.2% by mass or more, or 0.5% by mass or more, or for example, 30% by mass or less, or 20% by mass or less. When the metal ion content is above the lower limit, the adhesion rate of metal phosphate to the first fluoride particles tends to improve, and when the metal ion concentration is below the upper limit, it tends to be easier to uniformly adhere the metal phosphate to the surface of the first fluoride particles.

[0086] The ratio of the total number of moles of metal ions in a solution containing metal ions to the total number of moles of phosphate ions in the liquid medium, based on phosphorus atoms, may be, for example, 0.01 or more and 5 or less, preferably 0.1 or more, or 0.5 or more, preferably 3 or less, or 1.5 or less.

[0087] The contact temperature between the phosphate ions forming the metal phosphate and the metal ions may be, for example, 0°C to 50°C, and preferably 35°C or lower, 20°C or lower, 10°C or lower, or 5°C or lower. When the contact temperature is within the above range, the adhesion of the metal phosphate to the surface of the first fluoride particles tends to be more uniform. The contact time may be, for example, 1 minute to 4 hours, and preferably 10 minutes to 3 hours. Contact may be carried out while stirring the liquid medium. Note that the contact time includes the time required to add the solution containing the metal ions.

[0088] Following the adhesion step, a separation step may be provided to separate the second fluoride particles to which the metal phosphate has adhered from the liquid medium. Separation can be carried out, for example, by solid-liquid separation means such as filtration or centrifugation. The second fluoride particles obtained by solid-liquid separation may be subjected to washing, drying, or other treatments as needed.

[0089] Metal phosphates are arranged on the surface of the second fluoride particles obtained in the adhesion process. The shape of the arranged metal phosphates may be, for example, particulate. The shape of the particulate phosphates may be, for example, rod-shaped, needle-shaped, etc. The coverage rate of the metal phosphates on the surface of the second fluoride particles may be, for example, 50% or more, preferably 80% or more, or 90% or more.

[0090] A method for producing a fluoride phosphor may further include an alkali treatment step in which the second fluoride particles obtained in the adhesion step are brought into contact with an alkaline liquid medium to obtain third fluoride particles. By alkali treatment of the second fluoride particles to which metal phosphates are attached, third fluoride particles in which the metal phosphates are more uniformly distributed can be obtained.

[0091] The liquid medium in the alkaline treatment process may contain water and an alkaline substance. The liquid medium may further contain reducing agents such as hydrogen peroxide, organic solvents, etc., as needed. Examples of organic solvents that the liquid medium may contain include alcohol solvents such as ethanol and isopropanol, ketone solvents such as acetone and methyl ethyl ketone, and ether solvents such as diethyl ether and diisopropyl ether. When the liquid medium contains an organic solvent, the content of the organic solvent in the liquid medium may be, for example, 50% by volume or more and 99% by volume or less, preferably 80% by volume or more, or 95% by volume or less. When the liquid medium contains a reducing agent, the content of the reducing agent in the liquid medium may be, for example, 0.5% by mass or more and 10% by mass or less, preferably 2% by mass or more, or 5% by mass or less.

[0092] Examples of alkaline substances contained in the liquid medium include basic compounds such as ammonia, sodium hydroxide, and potassium hydroxide. The pH of the liquid medium may be, for example, 8 to 13, preferably 9 or higher, or 10 or higher, and may be 12 or lower, or 11 or lower. When the pH of the liquid medium is within the above range, zinc phosphate tends to dissolve and form a film. The pH of the liquid medium is measured at 25°C.

[0093] The contact temperature between the second fluoride particles and the alkaline liquid medium may be, for example, 10°C to 50°C, preferably 20°C to 35°C. The contact time may be, for example, 1 minute to 4 hours, preferably 60 minutes to 3 hours. Contact may be carried out while stirring the liquid medium.

[0094] A separation step may be provided after the alkali treatment step to separate the third fluoride particles from the liquid medium. Separation can be carried out by solid-liquid separation means such as filtration or centrifugation. The third fluoride particles obtained by solid-liquid separation may be subjected to washing, drying, or other treatments as needed.

[0095] A metal phosphate is arranged on the surface of the third fluoride particles obtained in the alkali treatment step. The shape of the arranged metal phosphate may be, for example, a film. The coverage rate of the metal phosphate on the surface of the third fluoride particles may be, for example, 50% or more, preferably 80% or more, or 90% or more.

[0096] A method for producing a fluoride phosphor may further include an oxide coating step, in which a second fluoride particle obtained in an adhesion step or a third fluoride particle obtained in an alkali treatment step is brought into contact in a liquid medium with a metal alkoxide containing at least one selected from the group consisting of silicon (Si), aluminum (Al), titanium (Ti), zirconium (Zr), tin (Sn), and zinc (Zn), thereby obtaining a fourth fluoride particle in which an oxide derived from the metal alkoxide is disposed on at least a portion of the surface of the second or third fluoride particle. In a light-emitting device equipped with a fluorescent member containing the obtained fourth fluoride particle and a resin, reliability is further improved, for example, in high-temperature and high-humidity environments.

[0097] In the oxide coating step, the prepared second fluoride particles or third fluoride particles (hereinafter collectively referred to as "phosphate-attached fluoride particles") are brought into contact with a metal alkoxide containing at least one selected from the group consisting of silicon, aluminum, titanium, zirconium, tin, and zinc in a liquid medium to coat the phosphate-attached fluoride particles with an oxide derived from the metal alkoxide and obtain a fourth fluoride phosphor. By solvolysis of the metal alkoxide, an oxide derived from the metal alkoxide can be generated, and a fluoride phosphor containing fourth fluoride particles covered with the generated oxide can be obtained.

[0098] The aliphatic group of the alkoxide constituting the metal alkoxide may have, for example, 1 to 6 carbon atoms, preferably 1 to 4 or 1 to 3 carbon atoms. The metal alkoxide contains at least one element selected from the group consisting of silicon, aluminum, titanium, zirconium, tin, and zinc, but may contain at least silicon. The metal and aliphatic group contained in the metal alkoxide may each be only one type, or may be a combination of two or more types.

[0099] Specific examples of metal alkoxides include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, trimethoxyaluminum, triethoxyaluminum, triisopropoxyaluminum, tetramethoxytitanium, tetraethoxytitanium, tetraisopropoxytitanium, tetramethoxyzirconium, tetraethoxyzirconium, tetraisopropoxyzirconium, tetraethoxytin, dimethoxyzinc, diethoxyzinc, etc., and may contain at least one selected from the group consisting of these, preferably at least one selected from the group consisting of tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane. The metal alkoxide in the oxide coating step may be used alone or in combination of two or more.

[0100] The amount of metal alkoxide added in the oxide coating process may be, as an amount added in terms of oxide, for example, 0.3% to 30% by mass, preferably 1% or more by mass, or 3% or more by mass, and preferably 25% or less by mass, or 20% or less by mass, based on the total mass of phosphate-attached fluoride particles. Furthermore, the amount of metal alkoxide added in the oxide coating process may be, as an amount of metal alkoxide added, for example, 0.5% to 110% by mass, preferably 2% or more by mass, or 5% or more by mass, and preferably 90% or less by mass, or 75% or less by mass, based on the total mass of fluoride particles.

[0101] Contact between phosphate-adhered fluoride particles and metal alkoxides is carried out in a liquid medium. Examples of liquid mediums include water; alcohol solvents such as methanol, ethanol, and isopropyl alcohol; nitrile solvents such as acetonitrile; and hydrocarbon solvents such as hexane. The liquid medium may contain at least water and an alcohol solvent. If the liquid medium contains an alcohol solvent, the content of the alcohol solvent in the liquid medium may be, for example, 60% by mass or more, preferably 70% by mass or more. The water content in the liquid medium may be, for example, 4% by mass or more and 40% by mass or less.

[0102] Furthermore, the liquid medium may further contain a pH adjusting agent. Examples of pH adjusting agents 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 adjusting agent, the pH of the liquid medium may be between 1 and 6 under acidic conditions, preferably between 2 and 5. Under alkaline conditions, it may be between 8 and 12, preferably between 8 and 11.

[0103] The mass ratio of the liquid medium to the phosphate-coated fluoride particles may 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, the fluoride particles tend to be coated with oxide more uniformly.

[0104] Contact between phosphate-attached fluoride particles and metal alkoxides can be achieved, for example, by adding the metal alkoxide to a suspension containing phosphate-attached fluoride particles. Stirring may be performed as needed. The contact temperature between the fluoride particles and the metal alkoxide may be, for example, 0°C to 70°C, preferably 10°C to 40°C. The contact time may be, for example, 1 hour to 12 hours. Note that the contact time includes the time required for adding the metal alkoxide.

[0105] A separation step may be provided after the oxide coating step to separate the fourth fluoride particles from the liquid medium. Separation can be carried out by solid-liquid separation means such as filtration or centrifugation. The fourth fluoride particles obtained by solid-liquid separation may be subjected to washing, drying, or other treatments as needed.

[0106] A method for producing a fluoride phosphor may include a surface treatment step in which the fluoride phosphor obtained in the synthesis step is treated with a coupling agent. The method may also include covering the fluoride particles with an oxide derived from a metal alkoxide, followed by a silane coupling treatment. In the surface treatment step, contact between the fluoride phosphor and the coupling agent can impart a surface treatment layer containing functional groups derived from the coupling agent to the surface of the fluoride phosphor. This, for example, improves the moisture resistance of the fluoride phosphor.

[0107] Specific examples of coupling agents used in the surface treatment process have been previously described. The amount of coupling agent used in the surface treatment process may be, for example, 0.5% to 10% by mass relative to the mass of the fluoride phosphor, preferably 1% to 5% by mass. The contact temperature between the fluoride phosphor and the coupling agent may be, for example, 0°C to 70°C, preferably 10°C to 40°C. The contact time between the fluoride phosphor and the coupling agent may be, for example, 1 minute to 10 hours, preferably 10 minutes to 1 hour.

[0108] Light-emitting device The light-emitting device includes a wavelength conversion member containing a first phosphor including the fluoride phosphor and a resin, and a light-emitting element having an emission peak wavelength in the wavelength range of 380 nm to 485 nm. The light-emitting device may further include other components as needed.

[0109] An example of a light-emitting device will be described based on the drawings. Figure 1 is a schematic cross-sectional view showing an example of a 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 having an emission peak wavelength in the short wavelength range of visible light, for example, in the range of 380 nm to 485 nm, 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 from a thermoplastic resin or a thermosetting resin. The molded body 40 has a recess formed therein with a bottom surface and sides, 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, and the pair of positive and negative electrodes are electrically connected to the first lead 20 and the second lead 30 via a wire 60. The light-emitting element 10 is sealed by a wavelength conversion member 50. The wavelength conversion member 50 contains a phosphor 70 including a fluoride phosphor that converts the wavelength of light from the light-emitting element 10. The phosphor 70 may include a first phosphor containing the fluoride phosphor and a light-emitting material that emits light having an emission peak wavelength in a different wavelength range from the fluoride phosphor when excited by light from the light-emitting element 10.

[0110] The wavelength conversion member may contain a resin and a phosphor. Examples of resins constituting the wavelength conversion member include silicone resin, epoxy resin, modified silicone resin, modified epoxy resin, and acrylic resin. For example, the refractive index of the silicone resin may be between 1.35 and 1.55, and more preferably between 1.38 and 1.43. Silicone resins within these refractive index ranges exhibit excellent light transmittance and can be suitably used as resins constituting the wavelength conversion member. Here, the refractive index of the silicone resin is the refractive index after curing and is measured in accordance with JIS K7142:2008. In addition to the resin and phosphor, the wavelength conversion member may further contain a light diffusing material. By including a light diffusing material, the directivity from the light-emitting element can be reduced and the viewing angle can be increased. Examples of light diffusing materials include silicon dioxide, titanium dioxide, zinc oxide, zirconium oxide, and aluminum oxide.

[0111] The light-emitting element emits light having an emission peak wavelength in the short-wavelength region of visible light, specifically in the wavelength range of 380 nm to 485 nm. The light-emitting element may be an excitation light source that excites a fluoride phosphor. Preferably, the light-emitting element has an emission peak wavelength in the range of 380 nm to 480 nm, more preferably in the range of 410 nm to 480 nm, and even more preferably in the range of 430 nm to 480 nm. It is preferable to use a semiconductor light-emitting element as the excitation light source. By using a semiconductor light-emitting element as the excitation light source, a stable light-emitting device can be obtained that is highly efficient, has high linearity of output to input, and is resistant to mechanical shock. As the semiconductor light-emitting element, for example, a semiconductor light-emitting element using a nitride-based semiconductor can be used. Preferably, the full width at half maximum of the emission peak in the emission spectrum of the light-emitting element is, for example, 30 nm or less.

[0112] The light-emitting device is composed of a first phosphor containing a fluoride phosphor. Details of the fluoride phosphor included in the light-emitting device are as previously described. The fluoride phosphor is contained, for example, in a wavelength conversion member that covers the excitation light source. In a light-emitting device in which the excitation light source is covered with a wavelength conversion member containing a fluoride phosphor, a portion of the light emitted from the excitation light source is absorbed by the fluoride phosphor and emitted as red light. By using an excitation light source that emits light having an emission peak 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 highly efficient light-emitting device can be provided.

[0113] The light-emitting device preferably further includes a light-emitting material other than a fluoride phosphor (hereinafter also referred to as a second phosphor) in addition to a first phosphor containing a fluoride phosphor. The light-emitting material other than the fluoride phosphor can be any material that absorbs light from a light source and converts it to light of a different wavelength than that of the fluoride phosphor. The light-emitting material can be included, for example, in a wavelength conversion member in the same way as the first phosphor.

[0114] The luminescent material may have an emission peak wavelength in the wavelength range of 495 nm or more and 590 nm or less, and is preferably at least one selected from the group consisting of β-sialon phosphors, halosilicate phosphors, silicate phosphors, rare earth aluminate phosphors, and nitride phosphors. The β-sialon phosphor may have a composition represented by, for example, the following formula (IIa). The halosilicate phosphor may have a composition represented by, for example, the following formula (IIb). The silicate phosphor may have a composition represented by, for example, the following formula (IIc). The rare earth aluminate phosphor may have a composition represented by the following formula (IId). The nitride phosphor may have a composition represented by, for example, the following formula (IIe), (IIf), or (IIg). When the wavelength conversion member includes a β-sialon phosphor or a perovskite-based luminescent material as a luminescent material other than the fluoride phosphor, when the light-emitting device is used as a light source for a backlight, for example, a light-emitting device with a wider range of color reproducibility can be obtained. When the wavelength conversion member includes a halosilicate phosphor, a silicate phosphor, a rare earth aluminate phosphor, or a nitride phosphor as a second phosphor other than the fluoride phosphor, when the light-emitting device is used as a light source for illumination, for example, a light-emitting device with higher color rendering properties or higher luminous efficiency can be obtained.

[0115] Si 6-t Al t O t N 8-t :Eu (IIa) (In formula (IIa), t is a number satisfying 0 < t ≤ 4.2.) (Ca,Sr,Ba)8MgSi4O 16 (F,Cl,Br)2:Eu (IIb) [[ID=二十]](Ba,Sr,Ca,Mg)2SiO4:Eu (IIc) (Y,Lu,Gd,Tb)3(Al,Ga)5O 12 :Ce (IId) (La,Y,Gd)3Si6N 11 :Ce (IIe) (Sr,Ca)LiAl3N4:Eu (IIf) (Ca,Sr)AlSiN3:Eu (IIg)

[0116] The average particle size of the light-emitting material may be, for example, 0.1 μm or more and 7 μm or less, preferably 0.2 μm or more, or 0.5 μm or more. Alternatively, the average particle size may be 5 μm or less, or 3 μm or less. The average particle size of the light-emitting material is measured by the FSSS method. The wavelength conversion member may contain one type of light-emitting material alone, or two or more types in combination.

[0117] The wavelength conversion member may further include at least one quantum dot in addition to the first phosphor. The quantum dot may absorb light from the light source and convert it to light of a different wavelength than the first phosphor, or it may convert it to light of a similar wavelength. Examples of quantum dots include quantum dots having a perovskite structure with a composition such as (Cs,FA,MA)(Pb,Sn)(Cl,Br,I)3 (where FA is formamidinium and MA is methylammonium), quantum dots having a chalcopyrite structure with a composition such as (Ag,Cu,Au)(In,Ga)(S,Se,Te)2, semiconductor quantum dots such as (Cd,Zn)(Se,S), and InP-based semiconductor quantum dots, and may include at least one selected from the group consisting of these. Here, in the formula representing the composition of the quantum dot, the multiple elements or cations listed separated by commas (,) mean that at least one of these multiple elements or cations is included in the composition.

[0118] The invention relating to this disclosure may encompass, for example, the following embodiments: [1] comprising first fluoride particles and a phosphate disposed on at least a portion of the surface of the first fluoride particles, The phosphate salt contains at least zinc in its composition, The first fluoride particles contain at least one element M selected from the group consisting of Group 4 elements, Group 13 elements, and Group 14 elements, an alkali metal, manganese, and fluorine atoms. When the number of moles of the alkali metal is 2, the number of moles of manganese is more than 0 and less than 0.2, the number of moles of element M is more than 0.8 and less than 1, and the number of moles of fluorine atoms is more than 5 and less than 7. A fluoride phosphor having such a composition.

[0119] [2] The first fluoride particles contain at least one of silicon and germanium as element M in their composition. When the number of moles of the alkali metal is 2, the total number of moles of silicon, germanium, and manganese is 0.9 or more and 1.1 or less. The fluoride phosphor according to [1].

[0120] [3] The first fluoride particles have a composition represented by the following formula (1). The fluoride phosphor according to [1] or [2]. A 1 c [M 1 1-b Mn b F d (1)

[0121] In formula (1), A 1 contains at least one selected from the group consisting of Li, Na, K, Rb, and Cs. M 1 contains at least one of Si and Ge, and may further contain at least one element selected from the group consisting of Group 4 elements and Group 14 elements. b satisfies 0 < b <​​​​​​​​​​​​​​[5] The fluoride phosphor according to any one of [1] to [4], wherein the zinc content of the phosphate is 0.01% by mass or more relative to the fluoride phosphor.

[0124] [6] A fluoride phosphor according to any one of [1] to [5], wherein an oxide comprising at least one selected from the group consisting of silicon, aluminum, titanium, zirconium, tin, and zinc is further disposed on at least a portion of the surface.

[0125] [7] The fluoride phosphor according to [6], wherein the oxide comprises at least silicon.

[0126] [8] The fluoride phosphor according to [6] or [7], wherein the oxide has an average thickness of 20 nm or more.

[0127] [9] Preparing first fluoride particles having a composition comprising element M, which includes at least one element selected from the group consisting of Group 4, Group 13, and Group 14 elements, an alkali metal, manganese, and a fluorine atom, wherein when the number of moles of the alkali metal is 2, the number of moles of manganese is greater than 0 and less than 0.2, the number of moles of element M is greater than 0.8 and less than 1, and the number of moles of fluorine atoms is greater than 5 and less than 7, In a liquid medium, the first fluoride particles are brought into contact with at least one metal ion selected from the group consisting of magnesium, calcium, strontium, and zinc, and a phosphate ion to obtain a second fluoride phosphor in which phosphate is attached to the first fluoride particles. A method for producing a fluoride phosphor containing [the specified substance].

[0128]

[10] The method for producing the first fluoride particles, further comprising adjusting the pH of the liquid medium containing the first fluoride particles to a range of 3 to 9. [9]

[0129]

[11] The second fluoride phosphor is brought into contact with an alkaline liquid medium to obtain third fluoride particles, Contacting the third fluoride particles with at least one metal alkoxide selected from the group consisting of silicon, aluminum, titanium, zirconium, tin and zinc in a liquid medium to dispose an oxide derived from the metal alkoxide on at least a part of the surface of the third fluoride particles; The production method according to [9] or

[10] including this.

[0130]

[12] The production method according to any one of [9] to

[11] , wherein the first fluoride particles contain at least one of silicon and germanium as element M in its composition, and when the number of moles of the alkali metal is 2, the total number of moles of silicon, germanium and manganese is 0.9 or more and 1.1 or less.

[0131]

[13] The production method according to any one of [9] to

[12] , wherein the first fluoride particles have a composition represented by the following formula (1). A 1 c[M 1 1-b Mn b F d (1) (In formula (1), A 1 includes at least one selected from the group consisting of Li, Na, K, Rb and Cs. M 1 includes at least one of Si and Ge, and may further include at least one element selected from the group consisting of Group 4 elements and Group 14 elements. b satisfies 0 < b < 0.2, and c is the absolute value of the charge of [M 1 1-b Mn b F d ions, and d satisfies 5 < d < 7.)

[0132]

[14] A light-emitting device including a wavelength conversion member including a fluoride phosphor according to any one of [1] to [8] and a resin, and a light-emitting element having an emission peak wavelength in a wavelength range of 380 nm or more and 485 nm or less.

Example

[0133] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0134] Comparative Example 1 According to known methods, the Mn content is 1.55 mass%, and K2[Si 0.938 Mn 0.062 We obtained fluoride particles A1, which are phosphors having a composition represented by [F6].

[0135] Example 1 To an aqueous sodium pyrophosphate solution (concentration 31.8 mmol / L) prepared by dissolving 1.61 g (3.61 mmol) of sodium pyrophosphate decahydrate in 113.4 g of pure water, 5.0 g of 35% by mass hydrogen peroxide solution was added. While stirring at room temperature (25°C) with a stirring blade at a rotation speed of 300 rpm, 100 g of fluoride particles A1 from Comparative Example 1 was added to prepare a phosphor slurry which would serve as the reaction mother liquor.

[0136] Next, an aqueous zinc sulfate solution (concentration 71.1 mmol / L), prepared by dissolving 1.56 g (5.42 mmol) of zinc sulfate heptahydrate in 76.3 g of pure water, was added dropwise to the phosphor slurry at room temperature over approximately 1 minute. After approximately 30 minutes at room temperature following the completion of the dropwise addition, stirring was stopped and the mixture was allowed to stand. The supernatant was removed, and the mixture was thoroughly washed with washing water containing 1% by mass of hydrogen peroxide. After solid-liquid separation of the resulting precipitate, it was washed with ethanol and dried at 90°C for 10 hours to produce fluoride phosphor E1 of Example 1, in which the surface was coated with zinc phosphate.

[0137] Example 2 Fluoride phosphor E2 of Example 2 was prepared in the same manner as in Example 1, except that the dropping time of the zinc sulfate aqueous solution was changed to approximately 120 minutes.

[0138] Example 3 Fluoride phosphor E3 of Example 3 was prepared in the same manner as in Example 2, except that the reaction temperature was changed to 2°C. The pH of the reaction mother liquor was 9 before the reaction, but decreased to 3.3 after the reaction was completed.

[0139] Example 4 Fluoride phosphor E4 of Example 4 was prepared in the same manner as in Example 3, except that a sodium pyrophosphate aqueous solution (concentration 22.7 mmol / L) was used to prepare the reaction mother liquor by dissolving 0.44 g (0.99 mmol) of sodium pyrophosphate decahydrate in 43.5 g of pure water, and a zinc sulfate aqueous solution (concentration 70.2 mmol / L) was used dropwise by dissolving 0.42 g (1.46 mmol) of zinc sulfate heptahydrate in 20.8 g of pure water.

[0140] Example 5 Fluoride phosphor E5 of Example 5 was prepared in the same manner as in Example 3, except that a sodium pyrophosphate aqueous solution (concentration 31.8 mmol / L) was used to prepare the reaction mother liquor by dissolving 4.10 g (9.19 mmol) of sodium pyrophosphate decahydrate in 288.7 g of pure water, and a zinc sulfate aqueous solution (concentration 70.9 mmol / L) was used dropwise by dissolving 3.96 g (13.77 mmol) of zinc sulfate heptahydrate in 194.2 g of pure water.

[0141] Example 6 Fluoride phosphor E6 of Example 6 was prepared in the same manner as in Example 3, except that a sodium pyrophosphate aqueous solution (concentration 31.9 mmol / L) was used to prepare the reaction mother liquor by dissolving 2.20 g (4.93 mmol) of sodium pyrophosphate decahydrate in 154.6 g of pure water, and a zinc sulfate aqueous solution (concentration 70.9 mmol / L) was used dropwise by dissolving 2.12 g (7.37 mmol) of zinc sulfate heptahydrate in 104.0 g of pure water.

[0142] Example 7 70 g of fluoride phosphor E6 from Example 6 was weighed and added to a solution prepared by mixing 130 ml of ethanol, 28.7 ml of ammonia water containing 16.2% by mass of ammonia, and 7.0 g of 35% by mass of hydrogen peroxide water. The mixture was stirred using a stirring blade at a rotation speed of 300 rpm, and stirring was stopped after 2 hours. After solid-liquid separation of the resulting precipitate, it was washed with ethanol and dried at 105°C for 10 hours to produce fluoride phosphor E7 from Example 7.

[0143] Example 8 60 g of fluoride phosphor E7 from Example 7 was weighed and added to a solution prepared by mixing 180 ml of ethanol and 24.6 ml of ammonia water containing 16.2% by mass of ammonia. The mixture was stirred at 300 rpm using a stirring blade while maintaining the liquid temperature at room temperature to form the reaction mother liquor. 6.1 g of tetraethoxysilane (TEOS:Si(OC2H5)4) was weighed and added dropwise to the stirring mother liquor over approximately 2 hours. Stirring was then continued for 1 hour, and then 5 g of 35% by mass of hydrogen peroxide (H2O2) was added before stopping the stirring. After solid-liquid separation of the resulting precipitate, it was washed with ethanol and dried at 105°C for 10 hours to produce fluoride phosphor E8 from Example 8, which was coated with silicon dioxide (SiO2). The amount of tetraethoxysilane added was approximately 3% by mass in terms of silicon dioxide relative to the fluoride particles.

[0144] Manufacturing example According to known methods, the Mn content is 1.69 mass%, and K2[Si 0.932 Mn 0.068 Fluoride particles, which are phosphors having a composition represented by [F6], were obtained. 50 g of the obtained fluoride particles were weighed and placed in a PTFE sample container (manufactured by San-ai Chemical Co., Ltd.: HUT-100R). 75 g of a liquid medium prepared by dissolving 300 g of KHF2 in 450 g of a 65 mass% HF aqueous solution was added, stirred to form a slurry, and then the container was capped. The capped sample container was placed in a stainless steel outer cylinder (manufactured by San-ai Chemical Co., Ltd.: HUS-100) and heat-treated in a 190°C constant temperature oven for 16 hours. After the heat treatment was completed, the PTFE sample container was removed from the stainless steel outer cylinder, the precipitate obtained in the sample container was transferred to a beaker, washed with 600 ml of 1% hydrogen peroxide solution, solid-liquid separation was performed, followed by ethanol washing, and drying at 90°C for 10 hours. The resulting product had a Mn content of 1.53 mass% and K2[Si 0.938 Mn 0.062 We prepared fluoride particles A2, which are phosphors having a first theoretical composition represented by [F6].

[0145] Example 9 Fluoride phosphor E9 of Example 9 was prepared in the same manner as in Example 3, except that a sodium pyrophosphate aqueous solution (concentration 31.8 mmol / L) was prepared by dissolving 2.34 g (5.25 mmol) of sodium pyrophosphate decahydrate in 164.9 g of pure water and 100 g of fluoride particles A2 to prepare the reaction mother liquor, and a zinc sulfate aqueous solution (concentration 71.0 mmol / L) was prepared by dissolving 3.02 g (10.50 mmol) of zinc sulfate heptahydrate in 148.0 g of pure water to be added dropwise.

[0146] evaluation (1) Zinc content For each fluoride phosphor obtained, the zinc content was analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES), and the zinc content relative to the fluoride phosphor (Zn analysis value) was determined. The results are shown in Table 1. In Table 1, "-" indicates that no zinc was added.

[0147] (2) Scanning electron microscope observation The fluoride phosphors obtained in Examples 1 to 3, 6, and 7 were imaged using a scanning electron microscope (SEM). The SEM images are shown in Figures 2A to 6B.

[0148] (3) Amount of silicon dioxide The fluoride phosphor obtained in Example 8 was subjected to compositional analysis by ICP emission spectroscopy. The amount of silicon dioxide covering the fluoride particles was calculated from the difference between the analyzed Si concentration of the silicon dioxide-covered fluoride phosphor obtained in Example 8 and the analyzed Si concentration of the fluoride phosphor in Example 7, and the silicon dioxide content (SiO2 analysis value) relative to the fluoride phosphor was determined. The results are shown in Table 1. In Table 1, "-" indicates no addition.

[0149] Manufacturing example of a light-emitting device 1 Each of the fluoride phosphors obtained in Examples 1 to 5 and Comparative Example 1 was used as the first phosphor. The first phosphor was mixed with the silicone resin in an amount of 120% by mass relative to the silicone resin to obtain a resin composition. Next, a molded body having a recess was prepared, and a light-emitting element made of a gallium nitride-based compound semiconductor with an emission peak wavelength of 451 nm was placed on the first lead at the bottom of the recess. Then, the electrodes of the light-emitting element were connected to the first lead and the second lead with wires. Furthermore, the resin composition was injected into the recess of the molded body using a syringe so as to cover the light-emitting element, and the resin composition was cured to form a wavelength conversion member, thereby manufacturing the light-emitting device 1.

[0150] Manufacturing example of a light-emitting device 2 Each of the fluoride phosphors obtained in Examples 6 to 9 and Comparative Example 1 was used as the first phosphor. A nitride phosphor having a composition represented by (Ca,Sr)AlSiN3:Eu and an emission peak wavelength around 625 nm was used as the second phosphor. The light-emitting device 2 was manufactured in the same manner as in Manufacturing Example 1, except that the first phosphor was mixed with the silicone resin at a concentration of 70% by mass relative to the silicone resin and the second phosphor at a concentration of 60% by mass relative to the silicone resin to obtain a resin composition.

[0151] Durability Rating 1 For each light-emitting device 1 using the fluoride phosphors obtained in Examples 1 to 5 and Comparative Example 1, durability evaluation 1 was performed by operating the device for 100 hours at a current of 400 mA in an environmental test chamber at a temperature of 85°C and a relative humidity of 85%. The luminous flux maintenance rate 1 (%) after durability evaluation 1 was calculated, with the luminous flux of the light-emitting device 1 before durability evaluation 1 set to 100%. A higher luminous flux maintenance rate 1 indicates better durability against high temperature and high humidity. The results are shown in Table 1. In Table 1, "-" indicates that the evaluation was not performed.

[0152] Durability Rating 2 For each light-emitting device 2 using the fluoride phosphors obtained in Examples 6 to 9 and Comparative Example 1, durability evaluation 2 was performed by operating it for 500 hours at a current of 400 mA in an environmental test chamber at a temperature of 85°C and a relative humidity of 85%. The luminous flux maintenance rate 2 (%) of light-emitting device 2 after durability evaluation 2 was calculated, with the luminous flux of light-emitting device 1 before durability evaluation 2 set to 100%. A higher luminous flux maintenance rate 2 indicates better durability against high temperature and high humidity. The results are shown in Table 1. In Table 1, "-" indicates that the evaluation was not performed.

[0153] [Table 1]

[0154] Compared to the luminous flux maintenance rate of the light-emitting device 1 using the fluoride phosphor in Comparative Example 1, the luminous flux maintenance rate of the light-emitting device 1 using the fluoride phosphor obtained in Examples 1 to 5 was higher, indicating high durability.

[0155] SEM images of the fluoride phosphors obtained in Examples 1 to 3, observed with a scanning electron microscope, are shown in Figures 2A, 2B, 3A, 3B, 4A, and 4B. The magnification of Figures 2A, 3A, and 4A is 2000x, and the magnification of Figures 2B, 3B, and 4B is 25000x. In each figure, the gray areas correspond to zinc phosphate and the black areas correspond to fluoride particles A1. From this, it can be seen that zinc phosphate adheres to the fluoride particles in the fluoride phosphors. Also, as shown in Figures 3A and 3B, when the dropping time during the reaction is increased, the shape of the zinc phosphate becomes rod-shaped. Furthermore, as shown in Figures 4A and 4B, when the reaction mother liquor is cooled, the particle size of the precipitated zinc phosphate decreases, and it can be seen that it adheres densely to the surface of the fluoride particles A1. The fluoride phosphors obtained in Examples 1 to 3 showed high durability due to the coating of zinc phosphate.

[0156] After durability evaluation 1, surface observation of the light-emitting device 1 revealed that the resin in the light-emitting device 1 using the fluoride particles obtained in Comparative Example 1 had deteriorated, whereas the resin deterioration was mitigated in the light-emitting device 1 using the fluoride phosphors obtained in Examples 1 to 3. It is thought that the adhesion of zinc phosphate to the surface of the fluoride particles reduces the contact area between the resin and the fluoride particles, thereby mitigating resin deterioration and resulting in high durability.

[0157] The Zn analysis values ​​of the fluoride phosphors in Examples 4 and 5 increased as the amount of zinc sulfate heptahydrate added increased. The light-emitting device 1 using the fluoride particles obtained in Example 4 had a higher luminous flux maintenance rate 1 than the light-emitting device 1 using the fluoride particles obtained in Comparative Example 1. This indicates that an effect can be obtained even with a small amount of zinc phosphate attached. The light-emitting device 1 using the fluoride particles obtained in Example 5 showed an even greater improvement in luminous flux maintenance rate 1 than the light-emitting device 1 using the fluoride particles obtained in Example 4, indicating that when reacted under the same conditions, a larger amount of zinc phosphate attached results in higher durability.

[0158] Figures 5A, 5B, 6A, and 6B show SEM images of the fluoride phosphors obtained in Examples 6 and 7, observed with a scanning electron microscope. The magnification of Figures 5A and 6A is 2000x, and the magnification of Figures 5B and 6B is 25000x. In Figures 6A and 6B, it can be seen that the zinc phosphate covering the fluoride particles has formed a film. This is thought to be because the granular zinc phosphate attached to the fluoride particles in Figures 5A and 5B dissolved in the alkaline solution and formed a film. The luminous flux maintenance rate 2 of the light-emitting device 2 using the fluoride phosphor in Example 7 is higher than that of the light-emitting device 2 using the fluoride phosphor in Example 6. This is thought to be because the film formation of zinc phosphate eliminates gaps between zinc phosphate particles, resulting in more uniform adhesion and thus higher durability.

[0159] The luminous flux maintenance rate of the light-emitting device 2 using the fluoride phosphor obtained in Example 8 was even higher than that of the luminous flux maintenance rate of the light-emitting device 2 using the fluoride phosphor obtained in Example 7. This is thought to be because silicon dioxide uniformly covers the fluoride phosphor to which zinc phosphate is attached, further improving moisture resistance and reducing elution from fluoride particles, thereby reducing degradation due to the reaction between the eluted substances and the resin.

[0160] The luminous flux maintenance rate 2 of the light-emitting device 2 using fluoride phosphors obtained in Example 9 was higher than that of the light-emitting device 2 using fluoride particles obtained in Comparative Example 1, indicating higher durability.

[0161] SEM images of the fluoride phosphors obtained in Example 9, observed with a fluoroelectron microscope, are shown in Figures 7A and 7B. As shown in Figure 5A, zinc phosphate did not adhere well to the grain boundaries of fluoride particle A1, but fluoride particle A2 obtained by autoclaving had fewer grain boundaries and zinc phosphate adhered uniformly. This is thought to have further reduced contact between the resin and fluoride particle A2, resulting in higher durability. In addition, fluoride particle A2 also had fewer small particles that are easily degraded by moisture, which is also considered to be a factor in the improved durability. [Explanation of symbols]

[0162] 10: Light-emitting element 20: First lead 30: Second lead 40: Molded body 50: Wavelength conversion component 60: Wire 70: Phosphor 100: Light-emitting device

Claims

1. The material comprises first fluoride particles and a phosphate disposed on at least a portion of the surface of the first fluoride particles, The phosphate salt contains at least zinc in its composition, The first fluoride particles are a fluoride phosphor having a composition in which, when the number of moles of the alkali metal is 2, the number of moles of manganese is greater than 0 and less than 0.2, the number of moles of element M is greater than 0.8 and less than 1, and the number of moles of fluorine atoms is greater than 5 and less than 7.

2. The fluoride phosphor according to claim 1, wherein the first fluoride particles contain at least one of silicon and germanium as element M in their composition, and when the number of moles of the alkali metal is 2, the total number of moles of silicon, germanium and manganese is 0.9 or more and 1.1 or less.

3. The fluoride phosphor according to claim 1, wherein the first fluoride particles have a composition represented by the following formula (1). A １ ｃ [M １ １－ｂ Mn ｂ F ｄ ] (1) (In formula (1), A １ includes at least one selected from the group consisting of Li, Na, K, Rb, and Cs. M １ includes at least one of Si and Ge, and may further include at least one element selected from the group consisting of Group 4 elements and Group 14 elements. b satisfies 0 < b < 0.2, and c is [M １ １－ｂ Mn ｂ F ｄ the absolute value of the charge of the ions, and d satisfies 5 < d < 7.)

4. The fluoride phosphor according to any one of claims 1 to 3, wherein the phosphate is zinc phosphate.

5. The fluoride phosphor according to any one of claims 1 to 3, wherein the zinc content of the phosphate is 0.01% by mass or more relative to the fluoride phosphor.

6. A fluoride phosphor according to any one of claims 1 to 3, wherein an oxide comprising at least one selected from the group consisting of silicon, aluminum, titanium, zirconium, tin, and zinc is further disposed on at least a portion of the surface.

7. The fluoride phosphor according to claim 6, wherein the oxide comprises at least silicon.

8. The fluoride phosphor according to claim 7, wherein the oxide has an average thickness of 20 nm or more.

9. To prepare first fluoride particles having a composition comprising element M, which includes at least one element selected from the group consisting of Group 4, Group 13, and Group 14 elements; an alkali metal; manganese; and fluorine atoms, wherein, when the number of moles of the alkali metal is 2, the number of moles of manganese is greater than 0 and less than 0.2, the number of moles of element M is greater than 0.8 and less than 1, and the number of moles of fluorine atoms is greater than 5 and less than 7. In a liquid medium, the first fluoride particles are brought into contact with at least one metal ion selected from the group consisting of magnesium, calcium, strontium, and zinc, and a phosphate ion to obtain a second fluoride phosphor in which phosphate is attached to the first fluoride particles. A method for producing a fluoride phosphor containing [the specified substance].

10. The manufacturing method according to claim 9, further comprising setting the pH of the liquid medium containing the first fluoride particles to a range of 3 to 9.

11. The second fluoride phosphor is brought into contact with an alkaline liquid medium to obtain third fluoride particles, The third fluoride particles are brought into contact with a metal alkoxide containing at least one selected from the group consisting of silicon, aluminum, titanium, zirconium, tin, and zinc in a liquid medium, so that oxides derived from the metal alkoxide are arranged on at least a portion of the surface of the third fluoride particles. The manufacturing method according to claim 9, which includes the following:

12. The manufacturing method according to any one of claims 9 to 11, wherein the first fluoride particles contain at least one of silicon and germanium as element M in their composition, and when the number of moles of the alkali metal is 2, the total number of moles of silicon, germanium and manganese is 0.9 or more and 1.1 or less.

13. The manufacturing method according to any one of claims 9 to 11, wherein the first fluoride particles have a composition represented by the following formula (1). A １ c[M １ １－ｂ Mn ｂ F ｄ ] (1) (In formula (1), A １ It includes at least one element selected from the group consisting of Li, Na, K, Rb, and Cs. １ It includes at least one of Si and Ge, and may further include at least one element selected from the group consisting of Group 4 and Group 14 elements. b satisfies 0 < b < 0.2, and c is [M １ １－ｂ Mn ｂ F ｄ (This is the absolute value of the ion's charge, where d satisfies 5 < d < 7.)

14. A light-emitting device comprising a wavelength conversion member containing a fluoride phosphor and a resin according to any one of claims 1 to 3, and a light-emitting element having an emission peak wavelength in the wavelength range of 380 nm to 485 nm.

Images