Fluoride fluorescent material particle, composite material, light-emitting device, and method for producing fluoride fluorescent material

Abstract

This fluoride fluorescent material particle has a composition represented by A2M(1-n)F6: Mn4+ n. The element A is one or more alkali metal elements including K. The element M is elemental Si, elemental Ge 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. When a cross section of this fluoride fluorescent material particle is subjected to elemental analysis using a JXA-8230 electron beam probe microanalyzer produced by JEOL Ltd. and accompanying software under conditions whereby the accelerating voltage is 15 kV, the irradiation current is 5×10-8 A, the measurement time is 30 ms, the size of the measurement region is 160×160 μm and the number of measurement points is 400×400 pixels, if the Mn level in the vicinity of the center of the fluoride fluorescent material particle is denoted by Pc and the Mn level in the vicinity of the surface is denoted by Ps, then Pc≥Ps.

Description

Fluoride phosphor particles, composite, light-emitting device, and method for manufacturing fluoride phosphor

[0001] The present invention relates to a fluoride phosphor particle, a composite, a light-emitting device, and a method for manufacturing a fluoride phosphor. More specifically, the present invention relates to a Mn-containing fluoride phosphor particle, a composite using the phosphor particle, a light-emitting device including the composite, and a method for manufacturing the Mn-containing fluoride phosphor particle.

[0002] Fluoride phosphors, particularly manganese (Mn)-containing fluoride phosphors, have been extensively studied so far from the viewpoint of application to wavelength conversion members in light-emitting diodes and the like.

[0003] Patent Document 1 describes a compound of the general formula: K ２ MnF ６ and has a diffuse reflectance of 60% or more for light with a wavelength of 550 nm. It also describes that a fluoride phosphor is produced by dissolving such potassium hexafluoromanganate in an aqueous hydrofluoric acid solution.

[0004] In Patent Document 2, a color-stable Mn is obtained by causing precipitation from an aqueous solution. ４＋ Methods for making doped complex fluoride phosphors are described.

[0005] Patent Document 3 describes the use of potassium hexafluoromanganate, 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 method for producing a manganese-based electrochemical reaction by inserting an anode and a cathode into a reaction solution containing a compound containing manganese with a valence of less than 4 and / or more than 4 and hydrogen fluoride, and applying a current density of 100 to 1000 A / m between the anode and cathode. ２The present invention also describes a method for producing a hexafluoromanganate (IV) salt, which is characterized by passing a current of 1000 kJ / s. Also, the present invention describes a method for producing a fluoride fluorescent material using the hexafluoromanganate (IV) salt thus produced.

[0007] Patent Document 5 describes a fluoride phosphor particle having at least one micro recess on the surface.

[0008] Patent Document 6 describes a compound of the general formula: A ２ SiF ６ The publication describes a method for producing a fluoride phosphor represented by the formula: Mn (element A is an alkali metal element containing at least potassium). This production method includes the steps of preparing an aqueous solution in which element A and fluorine are dissolved in a solvent, and adding to the aqueous solution solid silicon dioxide and a manganese compound that supplies manganese with a valence other than +7. In this production method, the amount of manganese compound added is in a range such that 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 compound of formula A ２ M （１－ｎ） F ６ : 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). The distance from the center to the surface of each particle constituting this powder is taken as 100%, and the average values ​​of Mn concentrations (mol%) measured at points of 0%, 25%, 50%, 75%, and 100% distance from the center are respectively expressed as [Mn ０ ], [Mn ２５ ], [Mn ５０ ], [Mn ７５ ], [Mn １００ ], then 0≦([Mn ０ ]+[Mn ２５ ]+[Mn ５０ ]) / ([Mn ５０ ]+[Mn ７５ ]+[Mn１００ ])≦0.9.

[0010] International Publication No. 2021 / 029289 Japanese Patent No. 6595998 JP 2018-123017 A Japanese Patent No. 6327125 International Publication No. 2022 / 202689 International Publication No. 2017 / 057671 Japanese Patent No. 2019-011429

[0011] As described above, various studies have been conducted on fluoride phosphors, particularly Mn-containing fluoride phosphors. However, with the widespread use of light-emitting devices using phosphors and the need for even higher performance in light-emitting devices using phosphors, further improvements in the properties of fluoride phosphors are desired.

[0012] The present inventors have attempted to improve Mn-containing fluoride phosphors, with the aim of improving the light-emitting properties.

[0013] The present inventors have investigated improvements to Mn-containing fluoride phosphors from every possible perspective. As a result of their investigations, they have found that the Mn concentration near the particle center and the Mn concentration near the particle surface in particulate Mn-containing fluoride phosphors appear to correlate with the luminescence characteristics. Based on this finding, the present inventors have further investigated the matter and have completed the invention provided below.

[0014] 1. Fluoride phosphor particles having a composition represented by the following general formula (1), which were measured using an electron probe microanalyzer manufactured by JEOL Ltd., product number JXA-8230, and the accompanying software at an acceleration voltage of 15 kV and a probe current of 5 × 10 －８ A fluoride phosphor particle, wherein Pc≧Ps is an Mn level near the center of the fluoride phosphor particle, and Ps is an Mn level near the surface of the fluoride phosphor particle, which are determined by elemental analysis of a cross section of the fluoride phosphor particle under the conditions of A, a measurement time of 30 ms, a measurement area size of 160×160 μm, and a number of measurement points of 400×400 pixels. ２ M （１－ｎ） F ６ : Mn ４＋ ｎIn general formula (1), the element A is one or more alkali metal elements containing K, and the element M is Si alone, Ge alone, or a combination of Si with one or more elements selected from the group consisting of Ge, Sn, Ti, Zr, and Hf, and 0<n≦0.1. 2. The fluoride phosphor particles according to 1., wherein the value of Pc−Ps is 4 to 20. 3. The fluoride phosphor particles according to 1. or 2., wherein the value of Pc / Ps is 1.2 to 3.0. 4. The fluoride phosphor particles according to any one of 1. to 3., wherein the value of Pc is 20 to 40. 5. The fluoride phosphor particles according to 1. to 4. 5. A fluoride phosphor particle according to any one of 1. to 4., wherein the value of Ps is 10 to 20. 6. A fluoride phosphor particle according to any one of 1. to 5., wherein the value of average Mn level Pa in the cross section of the fluoride phosphor particle is 14 to 20. 7. A fluoride phosphor particle according to any one of 1. to 6., wherein a region in the cross section of the fluoride phosphor particle where the Mn level is 31 or more accounts for 3 to 15% of the entire particle cross section. 8. A fluoride phosphor particle according to any one of 1. to 7., wherein the region in the cross section of the fluoride phosphor particle where the Mn level is 31 or more accounts for 3 to 15% of the entire particle cross section. 9. A fluoride phosphor particle according to any one of 1. to 8., wherein in the cross section of the fluoride phosphor particle, a region where the Mn level is 11 to 30 accounts for 70 to 90% of the entire particle cross section, and a region where the Mn level is 10 or less accounts for 0 to 20% of the entire particle cross section. 9. A fluoride phosphor particle according to any one of 1. to 8., wherein the Mn content based on ICP optical emission spectroscopy is 0.5 to 1.5 mass %. 10. A composite comprising the fluoride phosphor particle according to any one of 1. to 9., and a sealant that seals the fluoride phosphor particle. 11. A light emitting device comprising a light emitting element that emits excitation light, and the composite according to 10. that converts the wavelength of the excitation light. 12. A fluoride phosphor particle according to any one of 1. to 8., wherein an aqueous solution of hydrogen fluoride is added with KHF ２a second step of simultaneously adding a Mn-containing raw material and a Si-containing raw material to the first liquid and stirring to obtain a second liquid; and a third step of adding a Mn-containing raw material to the second liquid in one or more batches and stirring to obtain a third liquid, wherein the time at which the Mn-containing raw material and the Si-containing raw material are added in the second step is defined as time 0, and the time at which the Mn-containing raw material is finally added in the third step is defined as time T, and the total amount of the Mn-containing raw material added in the second step and the third step is defined as time 0. ｔ When this is the case, by time T / 2, it will be 0.60M ｔ 13. A method for producing a fluoride phosphor according to 12., wherein the Mn-containing raw material is added in a plurality of batches in the third step. 14. A method for producing a fluoride phosphor according to 12. or 13., wherein the Mn-containing raw material is K ２ MnF ６ 15. A method for producing a fluoride fluorescent material according to any one of 12. to 14., wherein the Si-containing raw material is SiO ２ A method for producing a fluoride phosphor, comprising:

[0015] The fluoride phosphor particles of the present invention have good light-emitting properties.

[0016] Fig. 1 is a schematic diagram of a light emitting device 1. Fig. 2 is a mapping image of Mn level in a cross section of a fluoride phosphor particle of Example 1. Fig. 3 is a mapping image of Mn level in a cross section of a fluoride phosphor particle of Example 2. Fig. 4 is a mapping image of Mn level in a cross section of a fluoride phosphor particle of Comparative Example 1. Fig. 5 is a diagram for helping the reader of this specification understand a method for analyzing the distribution of Mn in a cross section of a fluoride phosphor particle in the examples.

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings, which are for illustrative purposes only and may not correspond to actual products.

[0018] In this specification, unless otherwise specified, the expression "X to Y" in the description of a numerical range means at least X and at most Y. For example, "1 to 5% by mass" means "at least 1% by mass and at most 5% by mass."

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

[0020] <Fluoride phosphor particles> The composition of the fluoride phosphor particles of this embodiment is a compound represented by the general formula (1): A ２ M （１－ｎ） F ６ : Mn ４＋ ｎ In the general formula (1), the element A is one or more alkali metal elements containing K, the element M is Si alone, Ge alone, or a combination of Si with one or more elements selected from the group consisting of Ge, Sn, Ti, Zr, and Hf, and 0<n≦0.1.

[0021] An electron probe microanalyzer manufactured by JEOL Ltd., product number: JXA-8230, and the accompanying software were used. The accelerating voltage was 15 kV, and the probe current was 5 × 10 －８ By performing elemental analysis on a cross section of a fluoride phosphor particle of this embodiment under the conditions of A, measurement time 30 ms, measurement area size 160 × 160 μm, and number of measurement points 400 × 400 pixels, it is possible to determine the Mn level (an index corresponding to the Mn concentration; details are provided below) at each point on the cross section. In this measurement, when the Mn level near the center of the fluoride phosphor particle of this embodiment is Pc and the Mn level near the surface of the fluoride phosphor particle is Ps, Pc ≧ Ps.

[0022] The cross section of the fluoride phosphor particle can be obtained by embedding the particle in an epoxy resin or the like and then performing cross section milling. As a cross section milling technique, ion milling using a cross section polisher (CP) is preferably employed. To prevent charging during observation with an electron microscope, the cross section of the fluoride phosphor particle is preferably coated with osmium.

[0023] The Mn level is an index that quantitatively represents the characteristic X-ray intensity of Mn in the measurement area on the surface of the object to be measured, calculated by measurement using the above-mentioned analyzer and analysis using the above-mentioned software. According to information from JEOL Ltd., although the unit of Mn level is not mol% or mass%, the numerical value of the Mn level is positively correlated with the actual amount of Mn present, and therefore the amount of Mn can be discussed based on the value of the Mn level.

[0024] The present inventors have investigated the improvement of Mn-containing fluoride phosphors from every possible perspective. As a result of their investigations, they have found that the distribution of Mn, the luminescent center, in particulate Mn-containing fluoride phosphors is not uniform; for example, the Mn concentration near the particle's center may differ from that near the particle's surface. They have also found that the non-uniform distribution of Mn in the phosphor appears to be related to the luminescence characteristics. Furthermore, they have found that the Mn distribution in the phosphor can be controlled by devising a manufacturing method for the phosphor. Based on these findings, the present inventors have devised a manufacturing method for the phosphor to newly produce Mn-containing fluoride phosphor particles whose composition is represented by general formula (1) and whose Mn concentration near the center, Pc, is equal to or greater than the Mn concentration near the surface, Ps. These Mn-containing fluoride phosphor particles exhibit excellent luminescence characteristics. The reason why the luminescence characteristics are improved when Pc≧Ps is not entirely clear, but one possible reason is that crystal defects and heterophases (phases that do not contribute to luminescence) are less likely to occur near the center of the particle than near the surface.The presence of Mn (luminescence centers) near the center of the particle, where there are fewer crystal defects and heterophases, at a concentration equal to or higher than that near the surface of the particle is thought to improve luminescence characteristics such as quantum efficiency, even if the Mn amount in the entire particle is the same.

[0025] Incidentally, the fluoride phosphor particles of this embodiment have good luminescence characteristics and good moisture resistance, i.e., they tend to be less susceptible to deterioration due to moisture in the air. Since Pc≧Ps, i.e., the Mn concentration at the particle surface is smaller than or equal to the Mn concentration at the particle center, unintended environmental changes, deterioration, and falling off of Mn, which functions as the luminescence center, may be suppressed, thereby improving moisture resistance.

[0026] The method for producing fluoride phosphor particles of this embodiment will be described later, but will be briefly described here. Conventionally, a known method for producing a Mn-containing fluoride phosphor having a composition represented by general formula (1) involves growing fluoride phosphor crystals in an aqueous solution containing dissolved raw materials to obtain phosphor particles as a precipitate. The present inventors have investigated the reasons why the Mn concentration near the particle center and near the particle surface may differ in conventional Mn-containing fluoride phosphor particles. As a result of their investigation, they believe that (i) the crystal growth rate differs between the initial and middle stages of crystal growth of the fluoride phosphor, or (ii) the ease of Mn incorporation into the crystal may differ between the initial and middle stages of crystal growth. Although the details are unknown, it is possible that (i) and / or (ii) may occur due to solid-liquid equilibrium or kinetic factors at supersaturation. Based on this idea, the inventors decided to add the Mn-containing raw material to the aqueous solution in two or more batches when growing crystals of a fluoride phosphor in an aqueous solution, rather than adding it all at once. In particular, a large amount of the Mn-containing raw material is added to the aqueous solution at a relatively early stage of crystal growth, and a relatively small amount of the Mn-containing raw material, or no Mn-containing raw material, is added to the aqueous solution from the middle stage of crystal growth onward. This allows the Mn distribution in the fluoride phosphor particles to be controlled, and fluoride phosphor particles satisfying Pc≧Ps can be produced.

[0027] The fluoride phosphor particles of this embodiment will be described further.

[0028] (Composition: Regarding general formula (1)) Element A is one or more alkali metal elements containing K. Specifically, it can be potassium alone, 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 the content of potassium in element A is high (for example, 50 mol % or more of potassium in element A), and it is more preferable that element A is potassium alone.

[0029] The element M is Si alone, Ge alone, or a combination of Si and one or more elements selected from the group consisting of Ge, Sn, Ti, Zr, and Hf. From the viewpoint of chemical stability, it is preferable that the content of silicon in the element M is high (for example, 50 mol % or more of silicon in the element M), and it is more preferable that the element M is silicon alone.

[0030] In the general formula (1), n ​​may be in the range of 0<n≦0.1, but from the viewpoint of better light-emitting properties, it is preferable that n be in the range of 0.015≦n≦0.04.

[0031] (Pc and Ps, difference and ratio between them, etc.) In this embodiment, it is sufficient that Pc≧Ps, but the light-emitting properties and moisture resistance of the fluoride phosphor particles may be further improved by adjusting the values ​​of Pc and Ps (Mn level), the difference between Pc and Ps, the ratio between Pc and Ps, etc. In particular, when the values ​​of Pc and Ps are sufficiently different, there is a tendency that the effect of improving the light-emitting properties and moisture resistance is clearly obtained.

[0032] Pc is preferably 20 to 40, more preferably 25 to 40, and even more preferably 29 to 31. Ps is preferably 10 to 20, more preferably 10 to 19, and even more preferably 11 to 18. The value of Pc-Ps is preferably 4 to 20, and more preferably 11 to 18. The value of Pc / Ps is preferably 1.2 to 3.0, more preferably 1.5 to 3.0, and even more preferably 2.0 to 2.5. It is believed that when Ps itself is small and / or Ps is sufficiently small compared to Pc, the reaction between moisture in the air and Mn near the surface of the fluoride phosphor particles is suppressed, thereby further improving moisture resistance.

[0033] From the viewpoint of good luminescence characteristics and other performances, it is preferable that the Mn content in the fluoride phosphor particles be appropriately controlled. In other words, it is preferable that the "average" Mn content in the fluoride phosphor particles be within an appropriate numerical range. Specifically, the average Mn level Pa in the cross section of the fluoride phosphor particle that is the subject of elemental analysis is preferably 14 to 20, more preferably 16 to 20.

[0034] The "average" Mn content in the fluoride phosphor particles can also be used as an index of the Mn content determined by ICP emission spectroscopy (ICP: Inductively Coupled Plasma). Specifically, the Mn content of the fluoride phosphor particles of this embodiment based on ICP emission spectroscopy is preferably 0.5 to 1.5 mass%, more preferably 0.5 to 1.15 mass%, and even more preferably 0.6 to 1.10 mass%.

[0035] (Regarding the Distribution of Mn in the Cross Section of the Particle) When the cross section of the fluoride phosphor particle of this embodiment is subjected to elemental analysis and the Mn amount (Mn level) near the center and near the surface of the particle is considered, it is sufficient if Pc≧Ps holds. However, by appropriately controlling the distribution of Mn throughout the entire cross section, the luminescence characteristics, moisture resistance, etc. tend to be further improved.

[0036] Specifically, in the cross section of a fluoride phosphor particle to be subjected to elemental analysis, the region having an Mn level of 31 or more preferably accounts for 3 to 15% of the entire particle cross section, more preferably 5 to 12%, and even more preferably 7 to 9%. Furthermore, in the cross section of a fluoride phosphor particle to be subjected to elemental analysis, the region having an Mn level of 11 to 30 preferably accounts for 70 to 90% of the entire particle cross section, more preferably 73 to 85%. Furthermore, in the cross section of a fluoride phosphor particle to be subjected to elemental analysis, the region having an Mn level of 10 or less preferably accounts for 0 to 20% of the entire particle cross section, more preferably 4 to 20%, and even more preferably 7 to 20%. (Just to be clear, "%" here means area %.)

[0037] The above-mentioned range of the area ratio for the Mn distribution means that the particle cross section has relatively few regions where the Mn concentration is too high or too low, and has relatively many regions where the Mn concentration is neither too high nor too low, which can further improve the luminescence characteristics, moisture resistance, etc. The inventors have found that the internal quantum efficiency can be further improved by having the region with an Mn level of 31 or more account for 15% or less of the entire particle cross section. Fluoride phosphor particles having such a Mn distribution can be produced by appropriately controlling the number of times and timing at which Mn-containing raw materials are added to an aqueous solution when growing fluoride phosphor crystals in the aqueous solution, as has already been briefly described and will be described in detail later.

[0038] (Particle size distribution) With regard to the fluoride phosphor particles of this embodiment (more precisely, phosphor powder, which is an aggregate of phosphor particles), an appropriate particle size distribution can improve the light-emitting characteristics and make it easier to apply to various applications.

[0039] The cumulative 50% value (median value) in the volume-based particle size distribution curve of the phosphor particles of this embodiment is D ５０ When this is done, D ５０ is preferably 10 to 50 μm, more preferably 20 to 40 μm. ５０A moderate value of may result in, for example, a higher internal or external quantum efficiency.

[0040] From another perspective, the cumulative 50% value (median value) in the volume-based particle size distribution curve of the phosphor particles of this embodiment is D ５０ , the cumulative 10% value in the volume-based particle size distribution curve is D １０ , the cumulative 90% value in the volume-based particle size distribution curve is D ９０ , then (D ９０ -D １０ ) / D ５０ The value of is preferably 0.60 to 0.89, more preferably 0.77 to 0.84. (D ９０ -D １０ ) / D ５０ The value of D can be interpreted as an index that quantitatively indicates whether the particle size distribution is broad or sharp. ９０ -D １０ ) / D ５０ Fluoride phosphors having a particle size distribution that is not too large, i.e., that has a moderately sharp particle size distribution, tend to have excellent luminescence properties because they do not contain many ultrafine particles or coarse particles that tend to reduce quantum efficiency. The inventors have found that, as will be described later, in the production of fluoride phosphors, by appropriately controlling the timing and number of times that a Mn-containing raw material is added to an aqueous solution, (D ９０ -D １０ ) / D ５０ In some cases, the value of (D ９０ -D １０ ) / D ５０ By appropriately controlling the value of , the performance such as the light emitting characteristics may be further improved.

[0041] The volume-based particle size distribution curve can be obtained through measurement by laser diffraction scattering. For details of the measurement method, see the Examples below.

[0042] <Composite and Light-Emitting Device> The composite of this embodiment includes the above-described fluoride phosphor and a sealant that seals the fluoride phosphor. Furthermore, the light-emitting device of this embodiment includes a light-emitting element that emits excitation light and the above-described composite that converts the wavelength of the excitation light.

[0043] An example of a composite and a light-emitting device will be described below with reference to FIG.

[0044] FIG. 1 is a schematic diagram of a light-emitting device 1. The light-emitting device 1 includes 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 present on the lower part of the light-emitting element 20. When the terminals are connected to a power source, 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. When the excitation light is blue light, the blue light is wavelength-converted to red light by the composite 10 containing phosphor powder.

[0045] The composite 10 can be composed of the above-described phosphor powder and a sealant that seals the phosphor powder. Examples of the sealant include various curable resin materials (materials that cure with heat and / or light). 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 the sealant include silicone resin materials. Curable silicone resin materials are supplied by companies such as Dow Corning Toray and Shin-Etsu Chemical Co., Ltd. Silicone resin materials are preferred for their high transparency and excellent heat resistance. Other examples of the sealant 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.

[0046] There is no particular limitation on the size or shape of the light-emitting element 20. Depending on the application of the light-emitting device 1, the light-emitting element 20 can have any size or shape.

[0047] <Method for producing fluoride phosphor> As already briefly mentioned, fluoride phosphor particles satisfying Pc≧Ps can be produced by appropriately controlling the timing and number of times that a Mn-containing raw material is added to an aqueous solution when crystals of the fluoride phosphor are grown in the aqueous solution to form phosphor particles.

[0048] Specifically, fluoride phosphor particles satisfying Pc≧Ps can be manufactured through a series of steps including the following first to third steps. In this series of steps, particles (crystals) of fluoride phosphor particles are usually gradually precipitated in the second and third steps. In other words, it is preferable to appropriately adjust the concentration (amount used) of each raw material so that the aqueous solution is saturated in the second step. For the preferred concentration (amount used) of each raw material, the examples below can be referred to, for example. - Adding KHF to an aqueous solution of hydrogen fluoride ２ a first step of adding and stirring to obtain a first liquid; a second step of simultaneously adding a Mn-containing raw material and a Si-containing raw material to the first liquid and stirring to obtain a second liquid; and a third step of adding a Mn-containing raw material to the second liquid in one or more batches and stirring to obtain a third liquid.

[0049] In the above series of steps, the time when the Mn-containing raw material and the Si-containing raw material are added in the second step is defined as time 0, the time when the last Mn-containing raw material is added in the third step is defined as time T, and the total amount of the Mn-containing raw material added in the second step and the third step is defined as time M. ｔ When this is the case, by time T / 2, preferably 0.60M ｔ More preferably, 0.70M ｔ More preferably, 0.80M ｔ By adding the above Mn-containing raw material, it is possible to produce fluoride phosphor particles satisfying Pc≧Ps. In other words, by adding a relatively large amount of Mn-containing raw material to the aqueous solution at a relatively early stage in the process of growing crystal particles of the fluoride phosphor in the aqueous solution, it is possible to produce fluoride phosphor particles satisfying Pc≧Ps.

[0050] The concentration of the aqueous hydrogen fluoride solution in the first step is preferably 40% by mass or more, more preferably 55% by mass or more. The concentration of the aqueous hydrogen fluoride solution may be a saturated concentration. ２The amount of Mn atoms in the Mn-containing raw material introduced in the second and third steps can be adjusted appropriately in consideration of the value of n in general formula (1). The total amount of Mn atoms can be adjusted, for example, to 0.01 to 0.10 mol, more preferably 0.05 to 0.09 mol, relative to 1 mol of Si atoms in the Si-containing raw material introduced in the second step.

[0051] 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 for the Si site in the fluoride phosphor, thereby obtaining good luminescence characteristics, and among fluorides, hexafluoromanganates are preferred. Hexafluoromanganates include Na ２ MnF ６ , K. ２ MnF ６ , Rb ２ MnF ６ , MgMnF ６ , CaMnF ６ , SrMnF ６ , BaMnF ６ In particular, K ２ MnF ６ is preferable because it can simultaneously supply fluorine atoms and potassium atoms (potassium atoms correspond to element A in general formula (1)) that constitute the fluoride fluorescent material in addition to Mn. ２ SiF ６ , H ２ SiF ６ In view of the performance of the final fluoride phosphor particles and ease of availability as a raw material, silicon dioxide is preferred as the Si-containing raw material.

[0052] In addition, when producing a fluoride phosphor, for circumstances not specified above, known techniques may be referred to or appropriate trial and error may be carried out. Known techniques that can be referred to include, for example, the above-mentioned Patent Document 6 (WO 2017 / 057671).

[0053] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention.

[0054] The embodiments of the present invention will be described in detail based on Examples and Comparative Examples. However, it should be noted that the present invention is not limited to the Examples.

[0055] <Preparation of Raw Materials> The following raw materials were prepared. HF: Aqueous solution with a concentration of 55% by mass manufactured by Stella Chemifa Corporation. ２ MnF ６ : Stella Chemifa Corporation (K ２ MnF ６ (hereinafter referred to as "KMF") KHF ２ : Special grade reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. SiO ２ : FB-50R manufactured by Denka Co., Ltd.

[0056] Example 1: Production of fluoride phosphor particles Fluoride phosphor particles were produced by the following procedure. (First step) At room temperature, 2100 mL of an aqueous HF solution with a concentration of 55% by mass was placed in a Teflon (registered trademark) beaker. ２ 330 g of SiO2 was added and thoroughly stirred using a magnetic stirrer. This resulted in a homogeneous solution (first solution). (Second step) The beaker was immersed in the antifreeze solution in a cooling bath, and cooling was initiated while continuing to stir. Then, when the first solution reached -7°C, SiO2 was added to the first solution. ２72 g of KMF and 8.53 g of KMF were simultaneously added. The time of this addition was designated as time t = 0. In this manner, a second liquid was obtained. (Third Step) While continuing stirring and cooling, 4.27 g of KMF were added to the second liquid at t = 90 s, 2.13 g of KMF at t = 180 s, and 1.07 g of KMF at t = 270 s. Stirring was then stopped at t = 1500 s (25 minutes). (Post-Treatment) After the stirring in the third step was completed, the solution was allowed to stand to allow the yellow solid to fully precipitate. The supernatant was then removed, and the yellow solid was washed with hydrofluoric acid having a concentration of approximately 24% by mass, followed by washing with methanol. The washed solid was separated and recovered by filtration, and further dried to remove the remaining methanol by evaporation. After the drying treatment, the yellow powder that passed through a nylon sieve with 75 μm openings was separated and collected. In this way, 233.08 g of fluoride phosphor particles of Example 1 was obtained.

[0057] In the above procedure, the time T at which the Mn-containing raw material is finally added in the third step is 270 s. Therefore, T / 2 = 135 s. The amount of KMF added up to T / 2 = 135 s is 8.53 g + 4.27 g = 12.80 g. The total amount of KMF added in the second and third steps, M ｔ By calculating 12.80g / 16.00g, in Example 1, 0.80M ｔ It can be seen that the Mn-containing raw material was charged.

[0058] Example 2: Production of fluoride phosphor particles Fluoride phosphor particles were produced by the following procedure. (First step) A uniform solution (first liquid) was obtained in the same manner as in the first step of Example 1. (Second step) A beaker containing the first liquid was immersed in the antifreeze solution in a cooling bath, and cooling was initiated while stirring was continued. When the first liquid reached -7°C, SiO ２72 g of KMF and 12.00 g of KMF were simultaneously added. The time of this addition was designated as time t=0. In this manner, a second liquid was obtained. (Third Step) While continuing stirring and cooling, 6.02 g of KMF were added to the second liquid at t=90 s, 3.01 g of KMF at t=180 s, 1.51 g of KMF at t=270 s, 0.75 g of KMF at t=360 s, 0.38 g of KMF at t=450 s, 0.20 g of KMF at t=540 s, and 0.10 g of KMF at t=630 s. Stirring was then terminated at t=1500 s (25 minutes). (Post-treatment) The same post-treatment as in Example 1 was carried out. 241.69 g of fluoride phosphor particles of Example 2 was obtained.

[0059] In the above procedure, the time T at which the Mn-containing raw material is finally added in the third step is 630 s. Therefore, T / 2 is 315 s (5 minutes 15 seconds). The amount of KMF added up to T / 2 = 315 s is 12.00 g + 6.02 g + 3.01 g + 1.51 g = 22.54 g. The total amount of KMF added in the second and third steps, M ｔ By calculating 22.54g / 23.97g, in Example 2, 0.94M ｔ It can be seen that the Mn-containing raw material was charged.

[0060] Comparative Example 1: Production of Fluoride Fluorescent Particles Fluoride fluorescent particles were produced according to the following procedure. All procedures were carried out under cooling. (First Step) A uniform solution (first liquid) was obtained in the same manner as in the first step of Example 1. (Second Step) A beaker containing the first liquid was immersed in the antifreeze solution in a cooling bath containing the antifreeze solution, and cooling was started while stirring was continued. When the first liquid reached -7°C, SiO ２72g of KMF and 4.00g of KMF were simultaneously added. The time of this addition was designated as time t=0. In this manner, a second liquid was obtained. (Third Step) While continuing stirring and cooling, 4.00g of KMF was added to the second liquid at t=45 s, 4.00g of KMF at t=90 s, and 4.00g of KMF at t=135 s in sequence. Then, stirring was stopped at t=1500 s (25 minutes). (Post-treatment) A post-treatment similar to that of Example 1 was carried out. 234.75g of fluoride phosphor particles of Comparative Example 1 was obtained.

[0061] In the above procedure, the time T at which the Mn-containing raw material is finally added in the third step is 135 s. Therefore, T / 2 is 67.5 s. The amount of KMF added up to T / 2 = 67.5 s is 4.00 g + 4.00 g = 8.00 g. The total amount of KMF added in the second and third steps, M ｔ By calculating 8.00g / 16.00g, in Example 2, 0.50M ｔ It can be seen that the Mn-containing raw material was charged.

[0062] <Analysis of elemental composition of fluoride phosphor particles as a whole> The elemental composition of the fluoride phosphor particles obtained in Examples 1 and 2 and Comparative Example 1 was analyzed by ICP atomic emission spectroscopy for K, Si, and Mn, and by ion chromatography for F. As a result of the analysis, it was found that the molar ratios of K, Si, and F in the fluoride phosphor particles obtained in Examples 1 and 2 and Comparative Example 1 all satisfy the chemical formula K ２ SiF ６ The stoichiometric ratio was 2:1:6, which is derived from the above. ２ SiF ６ The amount of Mn in the fluoride phosphor particles is shown in Table 1 below.

[0063] <Elemental analysis of particle cross section> This was carried out according to the following procedure. (Particle cross section processing) First, the fluoride phosphor particles were embedded in an embedding epoxy resin known as "G2 epoxy." Then, the cross section of the fluoride phosphor particles was exposed by ion milling using a cross-section polisher (CP). After that, the cross section of the fluoride phosphor particles was coated with osmium. (Elemental analysis) Elemental analysis was carried out on the cross section of the fluoride phosphor particles embedded in the cured epoxy resin prepared above using an electron probe microanalyzer (product number: JXA-8230) manufactured by JEOL Ltd. and the accompanying software. Then, data on the Mn level at each measurement point was obtained. The detailed measurement conditions were as follows: Acceleration voltage: 15 kV, Exposure current: 5 x 10 －８ A Measurement time: 30 ms Size of measurement area: 160 × 160 μm Number of measurement points: 400 × 400 pixels (Based on the size of the measurement area and the number of measurement points described above, in this example, the Mn level was measured with an area of ​​0.4 × 0.4 μm as 1 pixel.)

[0064] For reference, FIG. 2 shows an elemental mapping image of the cross section of the fluoride phosphor particles of Example 1, FIG. 3 shows an elemental mapping image of the cross section of the fluoride phosphor particles of Example 2, and FIG. 4 shows a mapping image of the Mn level of the cross section of the fluoride phosphor particles of Comparative Example 1. In each figure, the straight dashed lines 1 to 5 drawn on the fluoride phosphor particles are for the following data analysis. The dashed lines were drawn from end to end of the particle cross section (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 portion with an Mn level of 5 or less was considered to be the cured product of the embedding epoxy resin, and the portion with an Mn level of 6 or more was considered to be the fluoride phosphor particle. (Supplementary information) - The reason for determining the "edge" of a particle cross section based on whether the Mn level was 5 or less or 6 or more: in the element mapping, pixels with a non-zero Mn level (maximum 5) existed even in parts that were clearly not particles (parts that clearly corresponded to the embedding epoxy resin). - For analytical purposes, the dashed lines 1 to 5 could not be drawn diagonally, so in the element mapping image, we first found a particle where a straight line could be drawn from one end of the particle to the other, and where that line passed through the particle center as closely as possible. Then, we drew a straight line (straight dashed line 1 to 5) from one end of that particle to the other.

[0065] (Calculation of Pc, Ps, etc. by analysis of obtained data) The following procedure was carried out. (1) From the data obtained by elemental analysis, the Mn level values ​​at the measurement points on the dashed lines 1 to 5 in Figures 2 to 4 were extracted. (2) For each of the dashed lines 1 to 5, the average value ps of the Mn level for 10 pixels at one end was calculated. １ ~P.S. ５ was calculated. １ ~P.S. ５ The arithmetic mean value of ps ａｖ Also, for the other end of the dashed lines 1 to 5, the average value ps' of the Mn level for the end 10 pixels was calculated. １ ~ps' ５ was calculated. １ ~ps' ５ The arithmetic mean value ps' of ａｖwas calculated. (3) (ps ａｖ +ps' ａｖ ) / 2 was used as Ps, that is, the Mn level near the surface of the fluoride phosphor particle. (4) For each of the dashed lines 1 to 5, the average value pc of the Mn level for 10 pixels near the midpoint (5 pixels on each side of the midpoint) １ ~pc ５ was calculated. １ ~pc ５ The arithmetic mean value of these values ​​was adopted as Pc, i.e., the Mn level near the center of the fluoride phosphor particle. (5) Based on Ps obtained in (3) and Pc obtained in (4), the difference, ratio, etc. between them was calculated.

[0066] (Analysis of Mn distribution in particle cross section) Using Microsoft Excel (trade name) software, the following were counted in the cross section of each particle: - the number of pixels with Mn level of 0 to 10, - the number of pixels with Mn level of 11 to 20, - the number of pixels with Mn level of 21 to 30, - the number of pixels with Mn level of 31 to 40, - the number of pixels with Mn level of 51 to 60, - the number of pixels with Mn level of 61 to 70, - the number of pixels with Mn level of 71 to 80, - the number of pixels with Mn level of 81 to 90, and - the number of pixels with Mn level of 91 to 100. Based on the counting results, the proportion (area ratio) of regions in the cross section of the fluoride phosphor particle where the Mn level is 31 or higher, the proportion (area ratio) of regions in the cross section of the Mn level is 11 to 30, and the proportion (area ratio) of regions in the cross section of the Mn level is 10 or lower were calculated. Furthermore, based on the counting results, the average value Pa of the Mn level in the cross section of the fluoride phosphor particle was calculated. (Pa = sum of Mn levels of all pixels in the cross section of the particle / total number of pixels in the cross section of the particle)

[0067] Supplementary Note: As with the calculation of Ps above, in the analysis of Mn distribution here, the criterion for the "end" of the particle cross section was whether the Mn level was 5 or less or 6 or more. In other words, near the end of the particle cross section, the part with an Mn level of 5 or less was considered to be the cured product of the embedding epoxy resin and was not counted, while the part with an Mn level of 6 or more was considered to be a fluoride phosphor particle and was counted. However, since there are pixels with an Mn level of 5 or less even in a part of the region of the particle cross section that is far enough inside the particle from the end, these pixels were counted.

[0068] To aid readers of this specification in understanding the above analysis, Fig. 5 shows the Mn level of each pixel (part of an Excel screenshot) in a part of the cross section of the fluoride phosphor particle of Example 1. The right side of the figure is the end.

[0069] <Particle size distribution measurement> 30 mL of ethanol was weighed into a 50 mL beaker, and 0.03 g of fluoride phosphor particles was placed therein. Next, the container was placed in a homogenizer (manufactured by Nippon Seiki Seisakusho, trade name US-150E) whose output had been adjusted to "Altitude: 100%" in advance, and pretreatment was carried out for 3 minutes. In this way, a dispersion of fluoride phosphor particles was obtained. A volume-based particle size distribution curve was obtained for the dispersion prepared in this way using a laser diffraction scattering particle size distribution analyzer (manufactured by Microtrackbell, trade name MT3300EXII). Then, from the obtained curve, D ５０ , D １０ and D ９０ asked for.

[0070] <Evaluation of Light-Emitting Properties> A standard reflector (Spectralon, manufactured by Labsphere) with a reflectance of 99% was set in the side opening (φ10 mm) of an integrating sphere (φ60 mm). Monochromatic light, dispersed to a wavelength of 455 nm from a light source (Xe lamp), was introduced into the integrating sphere via an optical fiber. The spectrum of the reflected light was then measured using a spectrophotometer (QE-2000, manufactured by Otsuka Electronics Co., Ltd.). The number of excitation light 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 set in the opening of the integrating sphere. The fluoride phosphor particles were then irradiated with monochromatic light with a wavelength of 455 nm. The reflected and fluorescent excitation light spectra were then measured using the spectrophotometer. The number of reflected excitation light photons (Qref) and the number of fluorescent photons (Qem) were calculated from the obtained spectral data. The number of reflected excitation light photons was calculated in the same wavelength range as the number of excitation light photons, and the number of fluorescent photons was calculated in the wavelength range of 465 to 800 nm. The following three characteristics were calculated from the obtained three types of photon counts: - Absorption rate (%): {(Qex-Qref) / Qex} x 100 - Internal quantum efficiency (%): {Qem / (Qex-Qref)} x 100 - External quantum efficiency (%): (Qem / Qex) x 100

[0071] <Evaluation of Moisture Resistance> Three grams of fluoride phosphor particles were placed on a watch glass and placed in a small high-temperature hygrostat (model: IW222) manufactured by Yamato Scientific Co., Ltd., and an exposure degradation test was performed under conditions of 60°C, 90% RH, and 25 hours. The external quantum efficiency was measured before and after the exposure degradation test. The moisture resistance was evaluated using the formula {(external quantum efficiency after test) / (external quantum efficiency before test)} × 100 (%). The closer the value calculated by this formula is to 100, the better the moisture resistance. The external quantum efficiency was measured as described above in <Evaluation of Light-Emitting Properties>.

[0072] Various information is summarized in Tables 1 and 2.

[0073]

[0074]

[0075] As shown in the table above, the internal quantum efficiency and external quantum efficiency of the fluoride phosphor particles of Examples 1 and 2, where Pc≧Ps (Pc−Ps is 0 or greater), were better than the internal quantum efficiency and external quantum efficiency of the fluoride phosphor particles of Comparative Example 1, where Pc<Ps (Pc−Ps is negative). In other words, the fluoride phosphor particles of Examples 1 and 2, where Pc≧Ps, exhibited good luminescence characteristics. Furthermore, from the difference in the manufacturing methods of Examples 1 and 2 and Comparative Example 1, it can be understood that appropriately adjusting the timing of adding the Mn-containing raw material when growing fluoride phosphor crystals in an aqueous solution can be a key to producing fluoride phosphor particles where Pc≧Ps.

[0076] In addition to good light-emitting properties, the fluoride phosphor particles of Example 1 exhibited better moisture resistance than the fluoride phosphor particles of Example 2. It is presumed that this result regarding moisture resistance is related to the fact that the fluoride phosphor particles of Example 1 had a smaller amount of Mn present near the particle surface. In other words, it is presumed that the fluoride phosphor particles of Example 1 had a smaller amount of Mn present on the particle surface than the fluoride phosphor particles of Example 2, and therefore hydrolysis of Mn was suppressed even in an environment of 60°C and 90% RH, thereby suppressing a decrease in external quantum efficiency.

[0077] This application claims priority based on Japanese Patent Application No. 2024-002436, filed January 11, 2024, the disclosure of which is incorporated herein in its entirety by reference.

[0078] 1 Light-emitting device 10 Composite 20 Light-emitting element

Claims

1. Fluoride phosphor particles represented by the following general formula (1), determined by elemental analysis of the cross-section of the fluoride phosphor particles under the conditions of an acceleration voltage of 15 kV, an irradiation current of 5 × 10 －８ A, a measurement time of 30 ms, a measurement area size of 160 × 160 μm, and 400 × 400 pixels of the number of measurement points, where the Mn level near the center of the fluoride phosphor particles is Pc and the Mn level near the surface of the fluoride phosphor particles is Ps, when Pc ≧ Ps, fluoride phosphor particles. General formula (1): A ２ M （１－ｎ） F ６ : Mn ４＋ ｎ In the general formula (1), the element A is one or more alkali metal elements containing K, the element M is a single Si, a single Ge, 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.

2. The fluoride phosphor particles according to claim 1, wherein the value of Pc - Ps is from 4 to 20.

3. The fluoride phosphor particles according to claim 1 or 2, wherein the value of Pc / Ps is from 1.2 to 3.

0.

4. The fluoride phosphor particles according to claim 1 or 2, wherein the value of Pc is from 20 to 40.

5. The fluoride phosphor particles according to claim 1 or 2, wherein the value of Ps is from 10 to 20.

6. The fluoride phosphor particles according to claim 1 or 2, wherein the average value Pa of the Mn level in the cross-section of the fluoride phosphor particles is from 14 to 20.

7. The fluoride phosphor particles according to claim 1 or 2, wherein the region where the Mn level is 31 or more in the cross-section of the fluoride phosphor particles occupies 3 to 15% of the entire particle cross-section.

8. The fluoride phosphor particles according to claim 1 or 2, wherein the region where the Mn level is from 11 to 30 in the cross-section of the fluoride phosphor particles occupies 70 to 90% of the entire particle cross-section, and the region where the Mn level is 10 or less occupies 0 to 20% of the entire particle cross-section.

9. The fluoride phosphor particles according to claim 1 or 2, wherein the Mn content based on ICP emission spectrometry is from 0.5 to 1.5% by mass.

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

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

12. Add KHF to an aqueous solution of hydrogen fluoride and stir to obtain a first liquid in a first step; in the first liquid, simultaneously add an Mn-containing raw material and an Si-containing raw material and stir to obtain a second liquid in a second step; and in the second liquid, add the Mn-containing raw material in one or more portions and stir to obtain a third liquid in a third step. A method for producing a fluoride phosphor, comprising: setting the time point of adding the Mn-containing raw material and the raw material containing Si in the second step as time 0, and setting the last addition time point of the Mn-containing raw material in the third step as time T; when the total amount of the Mn-containing raw material added in the second step and the third step is M ２ a method for producing a fluoride phosphor, wherein more than 0.60 M of the Mn-containing raw material is added by time T / 2. ｔ When the above is satisfied, ｔ ​ 13. The method for producing a fluoride phosphor according to claim 12, wherein in the third step, the Mn-containing raw material is charged in multiple portions.

14. The method for producing a fluoride phosphor according to claim 12 or 13, wherein the Mn-containing raw material is K ２ MnF ６ and the method for producing a fluoride phosphor.

15. A method for producing a fluoride phosphor according to claim 12 or 13, wherein the Si-containing raw material contains SiO ２ A method for producing a fluoride phosphor.

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