Fluoride phosphor particles, composites, light-emitting device, and method for producing fluoride phosphors

Abstract

Improvement of the light emission characteristics of fluoride phosphors, specifically improvement of the external quantum efficiency. 【Solution means】 Fluoride phosphor particles having a composition represented by the general formula (1): A2M (1-n) F6:Mn 4+ n In the general formula (1), element A is one or more alkali metal elements containing K, element M is Si alone, Ge alone, or a combination of one or more elements selected from the group consisting of Si and Ge, Sn, Ti, Zr, and Hf, and 0 < n ≤ 0.1. For these fluoride phosphor particles, using an electron probe microanalyzer manufactured by JEOL Ltd., product number: JXA-8230 and the attached software, with an acceleration voltage of 15 kV, an irradiation current of 5 × 10 -8 A, the value Pc of the Mn level near the center of the fluoride phosphor particles, determined from cross-sectional elemental analysis under the conditions of a measurement time of 30 ms, a measurement area size of 160 × 160 μm, and 400 × 400 pixels of the number of measurement points, is 36 to 58.

Description

[Technical Field]

[0001] This invention relates to fluoride phosphor particles, composites, light-emitting devices, and methods for producing fluoride phosphors. [Background technology]

[0002] Fluoride phosphors, particularly manganese (Mn)-containing fluoride phosphors, have been the subject of various studies, for example, from the perspective of their application as wavelength conversion components in light-emitting diodes.

[0003] Patent Document 1 describes potassium hexafluoride manganese, represented by the general formula K2MnF6, which has a diffuse reflectance of 60% or more for light with a wavelength of 550 nm. It also describes the production of a fluoride phosphor by dissolving such potassium hexafluoride manganese in an aqueous solution of hydrofluoric acid.

[0004] Patent Document 2 describes how to produce a precipitate from an aqueous solution of color-stable Mn 4+ A method for producing doped composite fluoride phosphors is described.

[0005] Patent Document 3 describes using potassium hexafluoride manganese, which has diffraction peaks at diffraction angles 2θ of 18.2±0.3°, 19.2±0.3°, 26.6±0.3°, 31.8±0.3°, and 42.0±0.3° in a powder X-ray diffraction pattern measured using CuKα rays, as a raw material for a fluoride phosphor.

[0006] Patent Document 4 describes a reaction solution containing a compound with manganese having a valence of less than 4 and / or more than 4, and hydrogen fluoride, into which an anode and a cathode are inserted, and a current density of 100 to 1000 A / m² is applied between these anode and cathode. 2 A method for producing hexafluoromanganase(IV) salt, characterized by passing an electric current through it, is described. Furthermore, a method for producing a fluoride phosphor using the hexafluoromanganase(IV) salt produced in this manner is also described.

[0007] Patent Document 5 describes fluoride phosphor particles having at least one minute recess on the surface.

[0008] Patent Document 6 describes a method for producing a fluoride phosphor represented by the general formula: A2SiF6:Mn (element A is an alkali metal element containing at least potassium). This production method includes a step of preparing an aqueous solution in which element A and fluorine are dissolved in a solvent, and a step of adding a manganese compound that supplies solid silicon dioxide and manganese other than +7 valent to the aqueous solution. In this production method, the addition amount of the manganese compound is in the range where the Mn content in the fluoride phosphor is 0.1% by mass or more and 1.5% by mass or less. In this production method, the fluoride phosphor precipitates in parallel with the dissolution of silicon dioxide in the aqueous solution.

[0009] Patent Document 7 describes a fluoride phosphor powder represented by the composition formula A2M (1-n) F6:Mn 4+ n (0 < n ≤ 0.1; A is one or more alkali metal elements containing at least K; M is one or more elements selected from Si, Ge, Sn, Ti, Zr, and Hf containing at least Si). Taking the distance from the center to the surface of each particle constituting this powder as 100%, the average values of the Mn concentration (mol%) measured at points where the distance from the center is 0%, 25%, 50%, 75%, and 100% are respectively [Mn0], [Mn 25 , [Mn 50 , [Mn 75 , [Mn 100 , then 0 ≤ ([Mn0] + [Mn 25 + [Mn 50 ) / ([Mn 50 + [Mn 75 + [Mn 100 ) ≤ 0.9 holds.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

[0011] As described above, various studies have been conducted on fluoride phosphors, particularly Mn - containing fluoride phosphors. However, with the spread of light - emitting devices using phosphors and the need for further improvement in the performance of light - emitting devices using phosphors, further improvement in the characteristics of fluoride phosphors is desired.

[0012] The inventors of the present invention have attempted to improve fluoride phosphors, aiming at improving the light - emitting characteristics, specifically, improving the external quantum efficiency. [Means for Solving the Problems]

[0013] The inventor examined the improvement of Mn - containing fluoride phosphors from all viewpoints. As a result of the examination, it was found that the Mn concentration near the center of particles in particulate Mn - containing fluoride phosphors seems to be correlated with the light - emitting characteristics. Based on this finding, the inventor further advanced the examination and completed the invention provided below.

[0014] 1. Fluoride phosphor particles having a composition represented by the following general formula (1), Using an electron probe microanalyzer manufactured by JEOL Ltd., part number: JXA-8230, and its accompanying software, with an acceleration voltage of 15kV and an irradiation current of 5×10⁻¹⁰, the following measurements were taken: -8 A. Fluoride phosphor particles in which, when the Mn level near the center of the fluoride phosphor particle is defined as Pc, the Pc value is between 36 and 58, as determined by elemental analysis of the cross-section of the fluoride phosphor particle under the conditions of a measurement time of 30 ms, a measurement area size of 160 × 160 μm, and a measurement point count of 400 × 400 pixels. General formula (1): A2M (1-n) F6:Mn 4+ n In general formula (1), Element A is one or more alkali metal elements containing K, Element M is either Si in elemental form, Ge in elemental form, or a combination of Si and one or more elements selected from the group consisting of Ge, Sn, Ti, Zr, and Hf. 0 <n≦0.1である。 2. Fluoride phosphor particles as described in 1. Fluoride phosphor particles in which, when the Mn level near the surface of the fluoride phosphor particles is determined from the elemental analysis described above, the value of Ps is between 12 and 30. 3. Fluoride phosphor particles as described in 1. or 2., Fluoride phosphor particles with a Pc / Ps value of 2.1 to 3.8. 4. A fluoride phosphor particle described in any one of 1. to 3., A fluoride phosphor particle in which the region with a Mn level of 31 or higher occupies 10-40% of the entire cross-section of the particle. 5. A fluoride phosphor particle described in any one of 1. to 4., In the cross-section of the fluoride phosphor particle, The region with a Mn level of 11-30 accounts for 50-70% of the entire particle cross-section. Fluoride phosphor particles in which the region with a Mn level of 10 or less accounts for 0-22% of the entire particle cross-section. 6. A fluoride phosphor particle described in any one of 1. to 5., Fluoride phosphor particles in which the average value of the Mn level in the cross-section of the fluoride phosphor particle is 18 to 35. 7. A fluoride phosphor particle described in any one of 1. to 6., Fluoride phosphor particles with a Mn content of 0.80-1.7% by mass, as determined by ICP emission spectroscopy. 8. A fluoride phosphor particle described in any one of 1. to 7., Fluoride phosphor particles with an external quantum efficiency of 69-75% when irradiated with excitation light of a wavelength of 455 nm. 9. A composite comprising fluoride phosphor particles as described in any one of 1. to 8., and a sealing material for sealing the fluoride phosphor particles. 10. A light-emitting device comprising a light-emitting element that emits excitation light, and a composite device according to 9. that converts the wavelength of the excitation light. 11. The first step involves adding KHF2 to an aqueous solution of hydrogen fluoride and stirring to obtain the first liquid, The second step involves adding a Mn-containing raw material to the first liquid and stirring to obtain a second liquid, A third step involves adding a Si-containing raw material to the second liquid and stirring to obtain a third liquid, The fourth step involves adding a Mn-containing raw material to the third liquid in one or more batches and stirring to obtain a fourth liquid, A method for producing a fluoride phosphor containing [the specified substance]. 12. A method for producing a fluoride phosphor as described in 11. A method for producing a fluoride phosphor, wherein the fourth step involves adding the Mn-containing raw material in multiple stages. 13. A method for producing a fluoride phosphor as described in 11. or 12., The method for producing a fluoride phosphor, wherein the Mn-containing raw material contains K2MnF6. 14. A method for producing a fluoride phosphor as described in any one of 11. to 13., A method for producing a fluoride phosphor, wherein the Si-containing raw material contains SiO2. [Effects of the Invention]

[0015] The luminescence properties of the fluoride phosphor particles of the present invention, specifically the external quantum efficiency, are excellent. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram of the light-emitting device 1. [Figure 2] This is an elemental mapping image of the cross-section of the fluoride phosphor particles from Example 1 (with some additions). [Figure 3] This is an elemental mapping image of the cross-section of the fluoride phosphor particles from Example 2 (with some additions). [Figure 4] This is an elemental mapping image of the cross-section of the fluoride phosphor particles from Example 3 (with some additions). [Figure 5] This is an elemental mapping image of the cross-section of the fluoride phosphor particles from Example 4 (with some additions). [Figure 6] Reference Example 1 is an elemental mapping image of a cross-section of fluoride phosphor particles (with some additions). [Figure 7] This is an elemental mapping image of a cross-section of fluoride phosphor particles from Reference Example 2 (with some additions). [Modes for carrying out the invention]

[0017] Embodiments of the present invention will be described in detail below with reference to the drawings. The drawings are for illustrative purposes only. The shapes and dimensional ratios of the components shown in the drawings do not necessarily correspond to those of actual items.

[0018] In this specification, the notation "X~Y" in descriptions of numerical ranges means "X or greater and Y or less" unless otherwise specified. For example, "1~5 mass%" means "1 mass% or greater and 5 mass% or less".

[0019] In this specification, the term "particle" may refer to a single particle (a single grain of particle) or to a powder, which is an aggregate of particles, depending on the context.

[0020] <Fluoride phosphor particles> The composition of the fluoride phosphor particles in this embodiment is represented by the following general formula (1). General formula (1): A2M (1-n) F6:Mn 4+ n In general formula (1), Element A is one or more alkali metal elements containing K, Element M is either Si in elemental form, Ge in elemental form, or a combination of Si and one or more elements selected from the group consisting of Ge, Sn, Ti, Zr, and Hf. 0 <n≦0.1である。

[0021] Using an electron probe microanalyzer manufactured by JEOL Ltd., part number: JXA-8230, and its accompanying software, with an acceleration voltage of 15kV and an irradiation current of 5×10⁻¹⁰, the following measurements were taken: -8 A. Elemental analysis of the cross-section of the fluoride phosphor particles of this embodiment is performed under the following conditions: measurement time 30 ms, measurement area size 160 × 160 μm, and measurement points 400 × 400 pixels. When the Mn level near the center of the fluoride phosphor particle, determined from this elemental analysis, is denoted as Pc, the value of Pc is 36 to 58, preferably 36 to 55, and more preferably 36 to 53. (For clarification, the "near center" of a fluoride phosphor particle can specifically refer to the midpoint of a line segment drawn vertically or horizontally (in a direction that allows pixel counting) on ​​a cross-sectional image of a fluoride phosphor particle. In the examples described later, Pc is calculated by averaging the Mn Level of 10 to 11 pixels near the midpoint. In this process, avoid drawing line segments that pass only near the edges of the fluoride phosphor particle and not near the center of the particle. Incidentally, according to the inventor's findings, in this embodiment, if the above line segment is drawn in an arbitrary manner, the Mn level near the midpoint of that line segment tends to be approximately the maximum value of the Mn level in the cross-section of the fluoride phosphor particle.)

[0022] The cross-section of fluoride phosphor particles can be obtained by embedding them in epoxy resin or the like, and then performing cross-sectional milling. Ion milling using a cross-section polisher (CP) is a preferred method for cross-sectional milling. To suppress electrostatic charge during observation with an electron microscope, it is preferable to coat the cross-section of the fluoride phosphor particles with osmium.

[0023] The Mn level is a quantitative index representing the characteristic X-ray intensity of Mn in the measurement area of ​​the surface of the object being measured, calculated by measurement using the analyzer described above and analysis using the software described above. According to information from JEOL Ltd., although the unit of the Mn level is not mol% or mass%, the Mn level value has a positive correlation with the actual amount of Mn present. Therefore, the amount of Mn can be discussed based on the value of the Mn level.

[0024] The inventors have investigated improvements to Mn-containing fluoride phosphors from all angles. As a result of their investigations, they found that in conventional particulate Mn-containing fluoride phosphors, even if a large amount of Mn raw material is used in its manufacture, some of the Mn is not incorporated into the phosphor, and even if it is incorporated, a phenomenon called concentration quenching occurs, resulting in the luminescence characteristics (specifically, external quantum efficiency) not improving as much as expected.

[0025] This invention was further developed based on the above findings. The manufacturing method was improved to incorporate a larger portion of Mn into the phosphor than conventional methods. As a result, it was possible to novelly produce fluoride phosphor particles with a high Mn level (Pc) near the center of the particle. Since Mn is thought to act as a luminescence center within the phosphor particles, the luminescence properties (specifically, external quantum efficiency) of fluoride phosphor particles with a high Pc are expected to be good.

[0026] As described above, in order to produce fluoride phosphor particles with a Pc of 36 to 58 according to this embodiment, ingenuity in the manufacturing method is required. If the manufacturing method is inappropriate, it may not be possible to produce fluoride phosphor particles with a Pc of 36 to 58. Preferred manufacturing methods will be described in detail later, but for example, fluoride phosphor particles with a Pc of 36 to 58 can be produced by a manufacturing process including the following steps 1 to 4. • The first step involves adding KHF2 to an aqueous solution of hydrogen fluoride and stirring to obtain the first solution. The second step involves adding a Mn-containing raw material to the first liquid and stirring to obtain the second liquid. • Third step: Adding Si-containing raw material to the second liquid and stirring to obtain the third liquid. • Step 4: Add the Mn-containing raw material to the third liquid in one or more batches and stir to obtain the fourth liquid.

[0027] The description of the fluoride phosphor particles in this embodiment will continue.

[0028] (Composition: Regarding general formula (1)) Element A is one or more alkali metal elements containing K. Specifically, it can be elemental potassium, or a combination of potassium and one or more alkali metal elements selected from lithium (Li), sodium (Na), rubidium (Rb), and cesium (Cs). From the viewpoint of chemical stability, it is preferable that element A has a high potassium content (for example, 50 mol% or more of element A is potassium), and it is more preferable that element A is elemental potassium.

[0029] Element M is a single element of Si, a single element of Ge, or a combination of one or more elements selected from the group consisting of Si and Ge, Sn, Ti, Zr, and Hf. From the perspective of chemical stability, the silicon content ratio in element M is preferably high (for example, 50 mol% or more of silicon in element M), and element M is more preferably a single silicon element.

[0030] In the general formula (1), n may be 0 < n ≤ 0.1, but from the perspective of better luminescence characteristics, it is preferably 0.015 ≤ n ≤ 0.04.

[0031] (Ps: Mn level near the surface of the fluoride phosphor particles) When the Mn level near the surface of the fluoride phosphor particles of this embodiment is Ps, the value of Ps is preferably 12 to 30, more preferably 12 to 28, and even more preferably 12 to 25. (For the sake of clarification, the "near the surface" of the fluoride phosphor particles refers to the end part and its vicinity in the cross section of the fluoride phosphor particles. The "end part" can be judged by whether the Mn Level is greater than the maximum value of the background. In the examples described later, the maximum value of the Mn Level of the background was 5, so the end part was determined by whether the Mn Level was 5 or less or 6 or more, and 10 pixels from that end part was regarded as the "near the surface".)

[0032] That Ps is 13 or more means that not only the central part of the phosphor particles but also a sufficient amount of Mn is incorporated into the end part (near the surface). Phosphor particles with Ps of 12 or more are considered to have better luminescence characteristics. From another perspective, from the perspective of suppressing moisture resistance, that is, performance change due to moisture in the air, Ps is preferably 30 or less. Since the reaction between moisture in the air and Mn near the surface of the fluoride phosphor particles is suppressed by Ps not being too large, the moisture resistance is considered to be further improved.

[0033] (Pc / Ps) The Pc / Ps value is preferably 2.1 to 3.8, more preferably 2.1 to 3.7, and even more preferably 2.1 to 3.6. A Pc / Ps value of 3.8 or less indicates that the distribution of Mn within the fluoride phosphor particles is not significantly biased, and that the distance between Mn atoms within the particles is not too close. A Pc / Ps value of 3.8 or less can be expected to suppress performance variations and improve quantum efficiency (especially internal quantum efficiency). A Pc / Ps value of 2.1 or higher means that the Mn concentration at the surface (edges) of the particle is sufficiently low, while the Mn concentration at the center of the particle is sufficiently high. A Pc / Ps value of 2.1 or higher allows for improved moisture resistance while simultaneously enhancing luminescence properties. Furthermore, the sufficiently low Mn concentration at the surface (edges of the cross-section) of the particle contributes to improved moisture resistance.

[0034] (Distribution of Mn in the particle cross-section) In this embodiment, when elemental analysis of the cross-section of the fluoride phosphor particles is performed and focusing on the amount of Mn (Mn level) near the center and near the surface of the particle, the Pc value should be between 36 and 58. However, by appropriately controlling the distribution of Mn throughout the entire cross-section, the luminescence characteristics and moisture resistance tend to be further improved.

[0035] Specifically, in the cross-section of the fluoride phosphor particle that is the subject of elemental analysis, the region with a Mn level of 11 to 30 preferably accounts for 50 to 70% of the entire particle cross-section, and more preferably 52 to 68%. Furthermore, in the cross-section of the fluoride phosphor particles that are the subject of elemental analysis, the region with a Mn level of 10 or less preferably accounts for 0-22% of the entire particle cross-section, and more preferably 5-22%. The region with a Mn level of 10 or less is considered to have little contribution to luminescence. Therefore, it is thought that the luminescence characteristics of the particles will be better if the area ratio of such regions is small.

[0036] The average value Pa of the Mn level in the cross-section of the fluoride phosphor particles is preferably 18 to 35, more preferably 18 to 30. A Pa of 18 or higher can be expected to further improve the luminescence characteristics. Furthermore, a Pa of 35 or lower can be expected to further improve the moisture resistance of the fluoride phosphor particles.

[0037] (Mn content based on ICP emission spectroscopy) For the "average" amount of Mn in fluoride phosphor particles, the Mn content determined by ICP emission spectroscopy (ICP: Inductively Coupled Plasma) can also be used as an indicator. Specifically, the Mn content of the fluoride phosphor particles in this embodiment, based on ICP emission spectroscopy, is preferably 0.80 to 1.7% by mass, and more preferably 0.80 to 1.4% by mass.

[0038] (External quantum efficiency) The luminescence characteristics of the fluoride phosphor particles in this embodiment can be quantitatively evaluated, for example, by the value of the external quantum efficiency. Conversely, it is preferable to manufacture the phosphor particles such that the external quantum efficiency value is relatively large.

[0039] Specifically, when the fluoride phosphor particles of this embodiment are irradiated with excitation light of a wavelength of 455 nm, the external quantum efficiency is preferably 69-75%, more preferably 69-74%. For details on the method for measuring external quantum efficiency, please refer to the description of the examples below.

[0040] (particle size distribution) In this embodiment, the fluoride phosphor particles (more precisely, phosphor powder, which is an aggregate of phosphor particles) have an appropriate particle size distribution, which can lead to improved luminescence characteristics and easier application to a variety of applications.

[0041] In this embodiment, the cumulative 50th percentile value (median) in the volume-based particle size distribution curve of the fluoride phosphor particles is D. 50 In that case, D50 The particle size is preferably 10 to 50 μm, more preferably 20 to 40 μm. 50 When this value is appropriate, it may be possible to further increase, for example, the internal or external quantum efficiency.

[0042] From another perspective, the cumulative 50th percentile value (median) in the volume-based particle size distribution curve of the fluoride phosphor particles of this embodiment is D 50 D is the cumulative 10% value in the volume-based particle size distribution curve. 10 D is the cumulative 90th percentile value in the volume-based particle size distribution curve. 90 , when (D 90 -D 10 ) / D 50 The value is preferably 0.60 to 0.89, more preferably 0.77 to 0.84. (D 90 -D 10 ) / D 50 The value can be understood as an indicator that quantitatively represents whether the particle size distribution is broad or sharp. (D 90 -D 10 ) / D 50 Fluoride phosphors with a moderately sharp particle size distribution, meaning that the value of fluoride is not too large, tend to have excellent luminescence properties because they do not contain too many ultrafine or coarse particles, which tend to reduce quantum efficiency. As a result of the inventor's research, in the production of fluoride phosphors, by appropriately controlling the timing and number of times the Mn-containing raw material is added to the aqueous solution, (D 90 -D 10 ) / D 50 In some cases, the value of can be controlled to a favorable degree. And, (D 90 -D 10 ) / D 50 By appropriately controlling the value of this parameter, performance characteristics such as luminescence can be further improved.

[0043] The volume-based particle size distribution curve can be obtained through measurement using laser diffraction scattering. For details of the measurement method, please refer to the examples provided later.

[0044] <Complex and light-emitting device> The composite of this embodiment comprises the fluoride phosphor particles described above and a sealing material that encapsulates the fluoride phosphor particles. Furthermore, the light-emitting device of this embodiment comprises a light-emitting element that emits excitation light and the composite element that converts the wavelength of the excitation light.

[0045] Below, an example of a composite and light-emitting device will be described with reference to Figure 1.

[0046] Figure 1 is a schematic diagram of the light-emitting device 1. The light-emitting device 1 comprises a composite 10 and a light-emitting element 20. The composite 10 is provided in contact with the upper part of the light-emitting element 20. The light-emitting element 20 is typically a blue LED. Terminals are located on the bottom of the light-emitting element 20. When these terminals are connected to a power supply, the light-emitting element 20 can emit light. The excitation light emitted from the light-emitting element 20 is wavelength-converted by the composite 10. If the excitation light is blue light, the blue light is wavelength-converted to red light by the composite 10 containing phosphor powder.

[0047] The composite 10 can be composed of the above-mentioned phosphor powder and a sealing material that seals the phosphor powder. As the sealing material, for example, various curable resin materials (materials that harden with heat and / or light) can be used. Any curable resin material can be used as long as it is sufficiently transparent and provides the optical properties required for displays and lighting devices. Examples of sealing materials include silicone resin materials. Curable silicone resin materials are supplied by companies such as Toray Dow Corning and Shin-Etsu Chemical. Silicone resin materials are preferable because they offer high transparency and excellent heat resistance. Other sealing materials include epoxy resin materials and urethane resin materials. The amount of phosphor powder particles in the composite 10 is, for example, 10 to 70% by mass, preferably 25 to 55% by mass.

[0048] The size and shape of the light-emitting element 20 are not particularly limited. Depending on the application of the light-emitting device 1, the light-emitting element 20 can be of any size and shape.

[0049] <Method for producing fluoride phosphors> As briefly mentioned earlier, the fluoride phosphor particles with a Pc of 36-58 in this embodiment can be manufactured by employing a properly designed manufacturing method. If the manufacturing method is inappropriate, it may not be possible to manufacture fluoride phosphor particles with a Pc of 36-58. According to the findings of this invention, it is difficult to manufacture fluoride phosphor particles with a Pc of 32-58 using conventional fluoride phosphor manufacturing methods.

[0050] Specifically, fluoride phosphor particles with a Pc of 36-58 can be produced by a manufacturing process that includes the following steps 1 to 4. However, adopting such a manufacturing process does not guarantee the production of fluoride phosphor particles with a Pc of 36-58. For example, if the amount of Mn-containing raw material added in step 2 and step 4 is not appropriately adjusted, it may not be possible to produce fluoride phosphor particles with a Pc of 36-58. • The first step involves adding KHF2 to an aqueous solution of hydrogen fluoride and stirring to obtain the first solution. The second step involves adding a Mn-containing raw material to the first liquid and stirring to obtain the second liquid. • Third step: Adding Si-containing raw material to the second liquid and stirring to obtain the third liquid. • Step 4: Add the Mn-containing raw material to the third liquid in one or more batches and stir to obtain the fourth liquid.

[0051] Although the details are unclear, it is presumed that the arrangement of raw material inputs (Mn first, then Si), specifically the "third step of adding Si-containing raw materials" after the "second step of adding Mn-containing raw materials," contributes to increasing the Pc value.

[0052] The following provides a more detailed explanation of each of the above steps.

[0053] In the first step, KHF2 is added to an aqueous solution of hydrogen fluoride and stirred to obtain the first solution. The concentration of the aqueous solution of hydrogen fluoride in the first step is preferably 40% by mass or more, and more preferably 55% by mass or more. The concentration of the aqueous solution of hydrogen fluoride may also be the saturation concentration. The amount of KHF2 added in the first step can be, for example, 0.05 to 0.08 mol, preferably 0.0587 to 0.0726 mol, and more preferably 0.0615 to 0.0689 mol, per 1 mol of HF in the aqueous solution.

[0054] In the second step, the Mn-containing raw material is added to the first liquid obtained in the first step and stirred to obtain the second liquid. Examples of Mn-containing raw materials include hexafluoromanganates, permanganates, oxides (excluding permanganates), fluorides (excluding hexafluoromanganates), chlorides, sulfates, and nitrates. Among these, fluorides are preferred because they can efficiently substitute Mn into the Si sites in fluoride phosphors, resulting in good luminescence properties, and among fluorides, hexafluoromanganates are preferred. Examples of hexafluoromanganates include Na2MnF6, K2MnF6, Rb2MnF6, MgMnF6, CaMnF6, SrMnF6, and BaMnF6. K2MnF6 is particularly preferred because, in addition to Mn, it can simultaneously supply fluorine atoms and potassium atoms (potassium atoms correspond to element A in general formula (1)) that constitute the fluoride phosphor.

[0055] The total amount of Mn atoms in the Mn-containing raw material introduced in the second step and the fourth step described later can be adjusted as appropriate, taking into account the value of n in general formula (1). For example, the total amount of Mn atoms can be preferably 0.01 to 0.10 mol, more preferably 0.04 to 0.08 mol, per 1 mol of Si atoms in the Si-containing raw material introduced into the second liquid in the third step described later.

[0056] In order to produce fluoride phosphor particles with a Pc of 32 to 58, it is preferable that 40% or more of the total amount of Mn atoms in the Mn-containing raw material introduced in the second step and the fourth step described below be introduced in the second step, and more preferably 50% or more be introduced in the second step. On the other hand, when considering the optimization of the distribution of Mn in fluoride phosphor particles, including not only Pc but also values ​​such as Ps and Pa, it is preferable that 70% or less of the total amount of Mn atoms in the Mn-containing raw material introduced in the second step and the fourth step described later be introduced in the second step, and it is more preferable that 60% or less be introduced in the second step. In summary, of the total amount of Mn atoms in the Mn-containing raw material introduced in the second step and the fourth step described below, it is preferable that 40-70% are introduced in the second step, and more preferably that 50-60% are introduced in the second step.

[0057] In the third step, the Si-containing raw material is added to the second liquid obtained in the second step, and the mixture is stirred to obtain the third liquid. Typically, when the Si-containing raw material is added to the second liquid, crystal formation of the fluoride phosphor begins. Examples of Si-containing raw materials include silicon dioxide, K2SiF6, and H2SiF6. From the perspective of the performance of the final fluoride phosphor particles and the availability of the raw material, silicon dioxide is preferred as the Si-containing raw material. The molar ratio of Si to Mn is as described above. In other words, the amount of Si-containing raw material added should be adjusted as appropriate, referring to the molar ratio mentioned above.

[0058] In the fourth step, the Mn-containing raw material is added to the third liquid obtained in the third step, either once or in multiple batches, and stirred to obtain the fourth liquid. From the perspective of further improving performance by adjusting the values ​​of Ps and Pa, and suppressing the uneven distribution of Mn in the particles, it is preferable that the Mn-containing raw material be added to the third liquid in multiple stages in the fourth stage. Incidentally, "multiple stages" refers to, for example, 2 to 7 times, more preferably 2 to 3 times, from the perspective of improving performance as described above and from the perspective of not making the process excessively complicated. Furthermore, when adding the raw material in multiple stages, it is preferable to gradually decrease the amount of Mn-containing raw material added each time.

[0059] Furthermore, regarding matters not explicitly mentioned above in the manufacture of fluoride phosphors, one may refer to publicly available technology or conduct trial and error as appropriate. An example of publicly available technology that may be relevant is the aforementioned Patent Document 6 (International Publication No. 2017 / 057671).

[0060] Although embodiments of the present invention have been described above, these are merely examples, and various other configurations can be adopted. Furthermore, the present invention is not limited to the embodiments described above, and modifications, improvements, etc., within the scope that can achieve the objectives of the present invention are included in the present invention. [Examples]

[0061] Embodiments of the present invention will be described in detail based on examples and comparative examples. It should be noted that the present invention is not limited to these examples.

[0062] <Preparation of raw materials> The following ingredients were prepared. HF: A 55% by mass aqueous solution manufactured by Nitto Chemical Industry Co., Ltd. K2MnF6: Manufactured by Stella Chemifa Co., Ltd. (K2MnF6 may be abbreviated as "KMF" below.) KHF2: A special grade reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. SiO2: FB-50R manufactured by Denka Corporation

[0063] <Example 1: Production of fluoride phosphor particles> Fluoride phosphor particles were manufactured using the following procedure. [1st step] At room temperature, 2100 mL of a 55% by mass HF aqueous solution was placed in a PFA beaker. While cooling this beaker by immersing it in antifreeze in a cooling bath containing antifreeze, 2350 g of KHF was added and the mixture was thoroughly stirred using a magnetic stirrer. A homogeneous solution (Solution 1) was obtained. [Second process] When the first solution reached -7°C, 8.5g of KMF was added to the first solution and thoroughly stirred using a magnetic stirrer. This yielded a homogeneous solution (second solution). The starting point of this second step is defined as t=0. [3rd step] At t=90s, 72g of SiO2 was added to the second solution and thoroughly stirred using a magnetic stirrer. The addition of SiO2 initiated the formation of fluoride phosphor particles. The liquid obtained in the third step is designated as the third liquid. [4th step] To the third liquid, which was being stirred with a magnetic stirrer, 4.3g of KMF was added at t=180s, 2.1g at t=270s, and 1.1g at t=360s. Stirring was then continued until t=1500s, at which point stirring was terminated. [Post-processing] After the stirring in the fourth step was completed, the beaker was removed from the cooling tank and the solution was allowed to stand to allow the yellow solid to settle sufficiently. Then, the supernatant was removed and the yellow solid was washed with hydrofluoric acid at a concentration of approximately 24% by mass, and then washed with methanol. The washed solid was filtered to separate and recover the solid, and the remaining methanol was evaporated by drying. After drying, only the yellow powder that passed through a nylon sieve with a mesh size of 75 μm was classified and recovered. Based on the above, 231.72 g of fluoride phosphor particles for Example 1 was produced.

[0064] <Example 2: Production of fluoride phosphor particles> Except for the following two points, 245.45 g of fluoride phosphor particles for Example 2 were prepared in the same manner as in Example 1. (i) In the second step, the amount of KMF was changed to 9.6g. (ii) In the fourth step, the amount of KMF was changed so that 4.8g of KMF was added to the third liquid, which was being stirred with a magnetic stirrer, at t=180s, 2.4g of KMF at t=270s, and 1.2g of KMF at t=360s.

[0065] <Example 3: Production of fluoride phosphor particles> Except for the following two points, 234.67 g of fluoride phosphor particles for Example 3 were prepared in the same manner as in Example 1. (i) In the second step, the amount of KMF was changed to 10.7g. (ii) In the fourth step, the amount of KMF was changed so that 5.3g of KMF was added to the third liquid, which was being stirred with a magnetic stirrer, at t=180s, 2.7g of KMF at t=270s, and 1.3g of KMF at t=360s.

[0066] <Example 4: Production of fluoride phosphor particles> Except for the following two points, 239.49 g of fluoride phosphor particles for Example 4 were prepared in the same manner as in Example 1. (i) In the second step, the amount of KMF was changed to 7.4g. (ii) In the fourth step, the amount of KMF was changed so that 3.8g of KMF was added to the third liquid, which was being stirred with a magnetic stirrer, at t=180s, 1.8g of KMF at t=270s, and 1.0g of KMF at t=360s.

[0067] <Example 1: Manufacturing of fluoride phosphor particles> Fluoride phosphor particles were manufactured using the following procedure. [1] At room temperature, 2100 mL of a 55% by mass HF aqueous solution was placed in a PFA beaker. This beaker was cooled by immersing it in antifreeze in a cooling bath containing antifreeze, and 2350 g of KHF was added. The mixture was then thoroughly stirred using a magnetic stirrer. A homogeneous solution (Solution 1) was obtained. [2] When the first solution reached -7°C, 72g of SiO2 and 8.5g of KMF were simultaneously added to the first solution and thoroughly stirred using a magnetic stirrer. At this point, the formation of insoluble fluoride phosphor particles began. Let the starting point of [2] be t=0. [3] [2] After adding KMF, the liquid was stirred with a magnetic stirrer. At t=90s, 4.3g of KMF was added, at t=180s, 2.1g of KMF was added, and at t=270s, 1.1g of KMF was added. Stirring was then continued until t=1500s, at which point stirring was stopped. [Post-processing] The same post-processing as in Example 1 was performed. Then, 247.72 g of fluoride phosphor particles for the comparative example was produced.

[0068] <Example 2: Manufacturing of fluoride phosphor particles> Except for the following two points, 232.41 g of fluoride phosphor particles for Reference Example 2 were prepared in the same manner as in Example 1. (i) In the second step, the amount of KMF was changed to 6.4g. (ii) In the fourth step, the amount of KMF was changed so that 3.2g of KMF was added to the third liquid, which was being stirred with a magnetic stirrer, at t=180s, 1.6g of KMF at t=270s, and 0.8g of KMF at t=360s.

[0069] <Analysis of the elemental composition of fluoride phosphor particles as a whole> The elemental composition of the fluoride phosphor particles obtained in each example and reference example was analyzed by ICP emission spectroscopy for K, Si, and Mn, and by ion chromatography for F. Analysis revealed that the fluoride phosphor particles obtained in each example and reference example all had a molar ratio of K, Si, and F equal to the stoichiometric ratio of 2:1:6 derived from the chemical formula K2SiF6. Therefore, it was determined that crystals of K2SiF6 were obtained in each example and reference example. The amount of Mn in the fluoride phosphor particles is shown in the table below.

[0070] <Elemental analysis of particle cross-sections> I followed these steps. [Cross-sectional processing of particles] First, the fluoride phosphor particles were embedded using an embedding epoxy resin known as "G2 epoxy." Then, the cross-sections of the fluoride phosphor particles were exposed by ion milling using a cross-section polisher (CP). Subsequently, the cross-sections of the fluoride phosphor particles were coated with osmium. More specific procedures and conditions are shown below.

[0071] [Resin embedding] (i) Place the sample into the recesses of the silicone embedding plate (which has 12 x 5 x 3 mm recesses), filling each recess to the brim. Typically, about 0.2 g of sample fits into one recess. (ii) A heat-curing two-part epoxy resin (G2 epoxy manufactured by Gatan Co., Ltd.), heated to 80°C, is dropped into the depressions of the silicone embedding plate. The amount of epoxy resin used at this time is usually about 0.2 to 0.3 g. The sample and epoxy resin are then lightly mixed with a toothpick. (iii) Degass the area using a vacuum impregnation device under conditions of -100kPa for a total of 5 to 10 minutes. (iv) Using a dryer, heat at 90°C for 90 minutes, then at 130°C for another 30 minutes. (v) Remove the sample (cured material) formed by the hardening of the epoxy resin from the recess.

[0072] [Milling] The sample (cured material) prepared by the resin embedding method described above has areas where the particles are dense (closer to the bottom of the recess in the silicone embedding plate) and areas where the particles are sparse (further from the bottom of the recess in the silicone embedding plate) due to particle sedimentation before the epoxy resin fully hardens. For elemental mapping, it is preferable to cut out a portion where the particles are monodisperse and moderately dense. Therefore, the argon ion beam was irradiated so that it struck the side of the sample (cured material) where the particles were dense (closer to the bottom of the recess in the silicone embedding plate). The equipment used was the IM4000, IM4000Plus, or ArBlade5000, all manufactured by Hitachi High-Tech Corporation. The acceleration voltage was 6kV, and the processing time was approximately 2-5 hours. Incidentally, the processing time was adjusted so that 1 / 2 to 2 / 3 of the thickness of the sample (cured material) prepared by the resin embedding method described above could be removed. Specifically, with an acceleration voltage of 6kV, the optimal processing time was 5 hours when using the IM4000, 3 hours when using the IM4000Plus, and 2 hours when using the ArBlade5000. By milling under the above conditions, a recess was formed by removing a portion of the side surface in the denser part of the sample (hardened material) (the part closest to the bottom of the recess in the silicone embedding plate) in the depth direction. The following elemental analysis (elemental mapping) was performed on that recess.

[0073] [Elemental analysis] Elemental analysis was performed on cross-sections of fluoride phosphor particles embedded in the cured epoxy resin prepared as described above, using an electron probe microanalyzer (model number: JXA-8230) and its accompanying software manufactured by JEOL Ltd. Mn level data was obtained at each measurement point. The detailed measurement conditions were as follows: Acceleration voltage 15kV Irradiation current 5×10 -8 A Measurement time: 30ms Measurement area size: 160 × 160 μm Number of measurement points: 400 x 400 pixels (Based on the size of the measurement area and the number of measurement points described above, in each example and reference example, the Mn level was measured with a 0.4 × 0.4 μm area defined as 1 pixel.)

[0074] For reference, Figure 2 shows the elemental mapping image of the cross-section of the fluoride phosphor particles of Example 1, Figure 3 shows the elemental mapping image of the cross-section of the fluoride phosphor particles of Example 2, Figure 4 shows the Mn level mapping image of the cross-section of the fluoride phosphor particles of Example 3, Figure 5 shows the Mn level mapping image of the cross-section of the fluoride phosphor particles of Example 4, Figure 6 shows the Mn level mapping image of the cross-section of the fluoride phosphor particles of Reference Example 1, and Figure 7 shows the Mn level mapping image of the cross-section of the fluoride phosphor particles of Reference Example 2. In each figure, the straight dashed lines numbered 1-5 drawn on the fluoride phosphor particles are for the following data analysis. The dashed lines are drawn from one end of the particle cross-section to the other (the end of the particle cross-section corresponds to the surface of the particle before cutting). Here, the "end" of the particle cross-section was determined based on whether the Mn level was 5 or less or 6 or more. In other words, the part with an Mn level of 5 or less was considered to be the cured epoxy resin used for embedding, and the part with an Mn level of 6 or more was considered to be the fluoride phosphor particle. ※supplement The reason for determining the "edges" of the particle cross-section based on whether the Mn level was 5 or less or 6 or more is that, in elemental mapping, there were pixels with a Mn level that was not zero (maximum 5) even in areas that were clearly not particles (clearly areas corresponding to the embedding epoxy resin). Due to analytical constraints, it was not possible to draw the dashed lines 1-5 diagonally. In the elemental mapping image, we first found particles where a straight line could be drawn from one end of the particle to the other, and where that line passed as close to the center of the particle as possible. Then, we drew straight lines (the straight dashed lines 1-5) from one end of the particle to the other.

[0075] [Calculation of Pc, Ps, and Pc / Ps] I followed these steps. (1) From the data obtained from elemental analysis, the Mn level values ​​were extracted at the measurement points along the dashed lines 1 to 5 in Figures 2 to 5. (2) For each of the dashed lines 1 to 5, the average value of the Mn level for the 10 pixels at one end was calculated as ps1 to ps5. Then, the arithmetic mean of ps1 to ps5 was calculated as ps av The result was calculated. Furthermore, for the other end of dashed lines 1-5, the average values ​​of the Mn levels for the end 10 pixels, ps'1-ps'5, were calculated. Then, the arithmetic mean of ps'1-ps'5 was calculated. av The result was calculated. (3)(ps av +ps' av The value calculated by the formula ) / 2 was adopted as Ps, i.e., the Mn level near the surface of the fluoride phosphor particles. (4) For each of the dashed lines 1 to 5, the average values ​​of the Mn levels pc1 to pc5 were calculated for a 10-pixel area near the midpoint (5 pixels to the left and right of the midpoint if the number of pixels from end to end of the dashed line is even) or for an 11-pixel area (the midpoint and the 5 pixels to the left and right of it if the number of pixels from end to end of the dashed line is odd). The arithmetic mean of pc1 to pc5 was then adopted as Pc, i.e., the Mn level near the center of the fluoride phosphor particle. (5) Pc / Ps was calculated based on Ps obtained in (3) and Pc obtained in (4).

[0076] [Analysis of Mn distribution in particle cross-section] Using Microsoft's software Excel (product name), in the cross-section of each particle, • Number of pixels with Mn level between 0 and 10. • Number of pixels with Mn level between 11 and 20. • Number of pixels with Mn level between 21 and 30. • Number of pixels with Mn level between 31 and 40. • Number of pixels with Mn level between 51 and 60. • Number of pixels with Mn level between 61 and 70 • Number of pixels with Mn level between 71 and 80 • The number of pixels with a Mn level of 81-90, and • The number of pixels with a Mn level of 91-100. They counted. Based on the counting results, the proportion (area ratio) of regions with a Mn level of 31 or higher, regions with a Mn level of 11 to 30, and regions with a Mn level of 10 or lower were determined in the cross-section of the fluoride phosphor particles. Furthermore, based on the counting results, the average value Pa of the Mn level in the cross-section of the fluoride phosphor particles was determined. (Pa = sum of Mn levels of all pixels in the particle cross-section / total number of pixels in the particle cross-section)

[0077] <Particle size distribution measurement> 30 mL of ethanol was weighed into a 50 mL beaker. 0.03 g of fluoride phosphor particles were added to this ethanol, and the mixture was dispersed for 3 minutes using an ultrasonic homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd., product name: Ultrasonic Homogenizer US-150E) to prepare the measurement sample. The homogenizer settings were as follows: Altitude: 100%, Amplitude: 100%, Oscillation frequency: 19.5 kHz, Tip size: φ20, Amplitude: 32 ± 2 μm. The prepared sample was placed in a laser diffraction scattering particle size distribution analyzer (Microtrac MT3300EX II, manufactured by Microtrac Bell Co., Ltd.) to obtain a volume-based particle size distribution curve. From the obtained particle size distribution curve, D 10 (Cumulative 10% value), D 50 (Cumulative 50th percentile) and D 90 The (cumulative 90th percentile) was calculated. Also, the span value: (D 90 -D 10 ) / D 50 The result was calculated.

[0078] <Evaluation of Luminescence Properties> A standard reflector with a reflectivity of 99% (Labsphere, product name Spectralon) was placed in the side opening (φ10 mm) of an integrating sphere (φ60 mm). Monochromatic light, spectrally separated to a wavelength of 455 nm from a light source (Xe lamp), was introduced into this integrating sphere via an optical fiber. The spectrum of the reflected light was then measured using a spectrophotometer (Otsuka Electronics, product name QE-2000). The number of excitation photons (Qex) was calculated from the spectrum in the wavelength range of 450 to 465 nm. Next, a concave cell filled with fluoride phosphor particles to create a smooth surface was placed in the opening of an integrating sphere. The fluoride phosphor particles were then irradiated with monochromatic light at a wavelength of 455 nm. The spectra of the excited reflected light and fluorescence were then measured using a spectrophotometer. From the obtained spectral data, the number of excited reflected photons (Qref) and the number of fluorescent photons (Qem) were calculated. The number of excited reflected photons was calculated in the same wavelength range as the number of excited photons, and the number of fluorescent photons was calculated in the wavelength range of 465 to 800 nm. From the three types of photon counts obtained, the following three characteristics were calculated. Absorption rate (%): {(Qex-Qref) / Qex} × 100 • Internal quantum efficiency (%): {Qem / (Qex-Qref)} × 100 External quantum efficiency (%): (Qem / Qex) × 100

[0079] <Evaluation of moisture resistance> Three grams of fluoride phosphor particles were placed on a watch glass and subjected to an exposure degradation test under the conditions of 60°C, 90% RH, and 25 hours in a small high-temperature constant-humidity chamber (model: IW222) manufactured by Yamato Scientific Co., Ltd. External quantum efficiency was measured before and after exposure degradation tests. Moisture resistance was then evaluated using the formula {(External quantum efficiency after test) / (External quantum efficiency before test)} × 100 (%). A value closer to 100% in this formula indicates better moisture resistance. The external quantum efficiency was measured using the method described in <Evaluation of Luminescence Characteristics> above.

[0080] <Reference: Mn acquisition rate> Based on the following formula, we calculated the proportion of Mn in the raw material that was incorporated into the fluoride phosphor particles. The table below shows the calculation results in percentages (i.e., the value calculated using the following formula multiplied by 100%). [Calculation formula] Yield of fluoride phosphor particles (g) × {Mn content (mass%) based on ICP emission spectroscopy / 100} ÷ {Total amount of KMF added in the manufacturing process (g) × (atomic weight of Mn / molecular weight of KMF)}

[0081] Various information and data are summarized in the table below.

[0082] [Table 1]

[0083] [Table 2]

[0084] The fluoride phosphor particles in Examples 1-4, with Pc values ​​in the range of 36-58, showed better external quantum efficiency than the fluoride phosphor particles in Reference Examples 1 and 2, with Pc values ​​of 35 or less. [Explanation of Symbols]

[0085] 1. Light-emitting device 10 complex 20 Light-emitting elements

Claims

1. Fluoride phosphor particles whose composition is represented by the following general formula (1): Using an electron beam probe microanalyzer manufactured by JEOL Ltd., part number: JXA-8230, and its accompanying software, with an acceleration voltage of 15 kV and an irradiation current of 5 × 10⁻¹⁰, －８ A. Fluoride phosphor particles in which, when the Mn level near the center of the fluoride phosphor particle is denoted as Pc, the value of Pc is between 36 and 58, as determined by elemental analysis of the cross-section of the fluoride phosphor particle under the conditions of a measurement time of 30 ms, a measurement area size of 160 × 160 μm, and a measurement point count of 400 × 400 pixels. General form (1): A ２ M （１－ｎ） F ６ Mn ４＋ ｎ In general formula (1), Element A is one or more alkali metal elements containing K, Element M is either Si in elemental form, Ge in elemental form, or a combination of Si and one or more elements selected from the group consisting of Ge, Sn, Ti, Zr, and Hf. 0 < n ≤ 0.

1.

2. Fluoride phosphor particles according to claim 1 Fluoride phosphor particles in which, when Ps is the Mn level near the surface of the fluoride phosphor particles determined from the elemental analysis, the value of Ps is between 12 and 30.

3. Fluoride phosphor particles according to claim 1 or 2, Fluoride phosphor particles with a Pc / Ps value of 2.1 to 3.

8.

4. Fluoride phosphor particles according to claim 1 or 2, A fluoride phosphor particle in which the region with a Mn level of 31 or higher occupies 10 to 40% of the entire particle cross-section.

5. Fluoride phosphor particles according to claim 1 or 2, In the cross-section of the fluoride phosphor particle, The region with a Mn level of 11 to 30 accounts for 50 to 70% of the entire particle cross-section. Fluoride phosphor particles in which the region with a Mn level of 10 or less accounts for 0-22% of the entire particle cross-section.

6. Fluoride phosphor particles according to claim 1 or 2, Fluoride phosphor particles having an average value Pa of Mn level in the cross-section of the fluoride phosphor particle of 18 to 35.

7. Fluoride phosphor particles according to claim 1 or 2, Fluoride phosphor particles having a Mn content of 0.80 to 1.7% by mass, as determined by ICP emission spectrometry.

8. Fluoride phosphor particles according to claim 1 or 2, Fluoride phosphor particles having an external quantum efficiency of 69-75% when irradiated with excitation light of a wavelength of 455 nm.

9. A composite comprising fluoride phosphor particles according to claim 1 or 2, and a sealing material for sealing the fluoride phosphor particles.

10. A light-emitting device comprising a light-emitting element that emits excitation light, and a composite device according to claim 9 that converts the wavelength of the excitation light.

11. In an aqueous solution of hydrogen fluoride, add KHF ２ The first step involves adding and stirring to obtain the first liquid, The second step involves adding a Mn-containing raw material to the first liquid and stirring to obtain a second liquid, A third step involves adding a Si-containing raw material to the second liquid and stirring to obtain a third liquid, The fourth step involves adding a Mn-containing raw material to the third liquid in one or more batches and stirring to obtain a fourth liquid, A method for producing a fluoride phosphor containing [the specified substance].

12. A method for producing a fluoride phosphor according to claim 11, In the fourth step, the Mn-containing raw material is added in multiple stages, in a method for producing a fluoride phosphor.

13. A method for producing a fluoride phosphor according to claim 11 or 12, The Mn-containing raw material is K ２ MnF ６ A method for producing a fluoride phosphor, comprising

14. A method for producing a fluoride phosphor according to claim 11 or 12, The aforementioned Si-containing raw material is SiO ２ A method for producing a fluoride phosphor, including [the specified substance].

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