Potassium hexafluoromanganate powder, method of producing manganese-containing fluoride phosphor, manganese-containing fluoride phosphor, composite body, light-emitting device and method of producing potassium hexafluoromanganate powder

Abstract

To provide potassium hexafluoromanganate suitable for producing manganese-containing fluoride phosphor.SOLUTION: A diffuse reflectance ρd550 of a potassium hexafluoromanganate powder for light at a wavelength of 550 nm is 66.0-70.0%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to potassium hexafluoromanganate powder, a method for producing a manganese-containing fluoride phosphor, a manganese-containing fluoride phosphor, a composite, a light-emitting device, and a method for producing potassium hexafluoromanganate powder. [Background technology]

[0002] As a phosphor that can convert blue light emitted from a blue light-emitting diode into red light, K2SiF6:Mn 4+ A fluoride phosphor represented by the formula: is known. This phosphor is often referred to as "KSF phosphor." KSF phosphors are efficiently excited by blue light. Furthermore, the half-width of their emission spectra tends to be narrow and sharp. Therefore, by using KSF phosphors as red phosphors, it is possible to achieve excellent color rendering and color reproducibility without reducing the brightness of white LEDs.

[0003] KSF phosphors can be produced using potassium hexafluoromanganate (typically represented by the chemical formula K2MnF6) as a raw material. The properties of the raw material potassium hexafluoromanganate can affect the properties of the final KSF phosphor, so research has focused on the properties of potassium hexafluoromanganate and on the manufacturing methods of potassium hexafluoromanganate.

[0004] Patent Document 1 describes potassium hexafluoromanganate, which is represented by the general formula: K2MnF6 and has a diffuse reflectance of 60% or more for light with a wavelength of 550 nm. Patent Document 2 describes a method in which an anode and a cathode are inserted into a reaction solution containing a compound containing manganese whose valence is less than 4 and / or more than 4 and hydrogen fluoride, and a current density of 100 to 1000 A / m is applied between the anode and cathode. 2 The present invention describes a method for producing hexafluoromanganate (IV) salt, which is characterized by passing a current of Patent Document 3 describes 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 radiation. In Patent Document 4, Examples 1 to 3 describe a method for synthesizing and purifying K2MnF6.

[0005] The Experimental section of Non-Patent Document 1 describes that K2MnF6 was obtained through the reaction formula 2KMnO4 + 2KF + 10HF + 3H2O2 → 2K2MnF6 + 8H2O + 3O2↑. Non-Patent Document 2 discusses how the properties of the raw material potassium hexafluoromanganate affect the properties of the final KSF phosphor. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2021 / 029289 [Patent Document 2] Patent No. 6327125 [Patent Document 3] Japanese Patent Application Publication No. 2018-123017 [Patent Document 4] Patent No. 6595998 [Non-patent literature]

[0007] [Non-Patent Document 1] J.Mater.Chem.C,2016,4,9561 [Non-patent document 2] ACS Appl.Mater.Interfaces 2018,10,18845-18856 Summary of the Invention [Problem to be solved by the invention]

[0008] As mentioned above, the properties of manganese-containing fluoride phosphors, such as KSF phosphors, can be affected by the properties of their raw material, potassium hexafluoromanganate. As described in the cited prior art documents, attempts have been made to improve the properties of KSF phosphors produced using potassium hexafluoromanganate as a raw material. However, the inventors felt that there was still room for improvement in potassium hexafluoromanganate.

[0009] The present invention has been made in view of the above circumstances, and one of the objects of the present invention is to provide potassium hexafluoromanganate that is suitable for producing manganese-containing fluoride phosphors, such as KSF phosphors. [Means for solving the problem]

[0010] The present inventors have completed the invention provided below and solved the above problems.

[0011] 1. Diffuse reflectance ρd of light with a wavelength of 550 nm 550 A powder of potassium hexafluoromanganate having a % saturation of 66.0 to 70.0%. 2. 1. The potassium hexafluoromanganate powder according to claim 1, The diffuse reflectance of light with a wavelength of 310 nm is ρd 310 The diffuse reflectance of light with a wavelength of 455 nm is ρd 455 When this is the case, ρd 310 / ρd 455 Potassium hexafluoromanganate powder with a value of 1.60 or more. 3. 1. or 2. The potassium hexafluoromanganate powder according to Diffuse reflectance ρd of light with a wavelength of 310 nm 310 A powder of potassium hexafluoromanganate, having a % saturation point of 16.0 to 25.0%. 4. The potassium hexafluoromanganate powder according to any one of 1. to 3., Diffuse reflectance ρd of light with a wavelength of 455 nm 455 Potassium hexafluoromanganate powder, having a ZnO content of 9.0 to 15.0%. 5. The potassium hexafluoromanganate powder according to any one of 1. to 4., Potassium hexafluoromanganate powder with an average particle size of 35 to 70 μm as determined from electron microscope images. 6. A method for producing a manganese-containing fluoride fluorescent material, using the potassium hexafluoromanganate powder according to any one of 1. to 5. as a raw material. 7. 6. A manganese-containing fluoride phosphor obtained by the method for producing a manganese-containing fluoride phosphor described in 6. 8. 7. A composite comprising the manganese-containing fluoride phosphor according to Item 7. and an encapsulant that encapsulates the manganese-containing fluoride phosphor. 9. A light-emitting device comprising: a light-emitting element that emits excitation light; and the composite according to 8. that converts the wavelength of the excitation light. 10. A method for producing the potassium hexafluoromanganate powder according to any one of 1. to 5., a first step of adding a potassium source to an aqueous solution of hydrogen fluoride and stirring the mixture to obtain a first liquid; a second step of adding a Mn-containing raw material to the first liquid and stirring the mixture to obtain a second liquid; a third step of adding hydrogen peroxide to the second liquid and stirring the mixture to obtain a precipitate of potassium hexafluoromanganate; Including, A method for producing potassium hexafluoromanganate powder, wherein the liquid temperature in the third step is 0 to 30°C. 11. 10. A method for producing the potassium hexafluoromanganate powder according to claim 10, comprising the steps of: A method for producing potassium hexafluoromanganate powder, wherein the potassium source comprises KHF2. 12. 10. or 11. A method for producing a potassium hexafluoromanganate powder according to the above, comprising: The method for producing potassium hexafluoromanganate powder, wherein the Mn-containing raw material includes KMnO4. [Effects of the Invention]

[0012] According to the present invention, potassium hexafluoromanganate suitable for producing KSF phosphor is provided, and the KSF phosphor produced using the potassium hexafluoromanganate of the present invention has good properties. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of a light emitting device. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The drawings are for illustrative purposes only, and the shapes and dimensional ratios of the components in the drawings do not necessarily correspond to the actual products.

[0015] 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."

[0016] In this specification, potassium hexafluoromanganate may be abbreviated as "KMF."

[0017] <Potassium hexafluoromanganate (KMF) powder> The diffuse reflectance ρd of the KMF powder of this embodiment at a wavelength of 550 nm 550 This value is preferably 66.5 to 70.0%, more preferably 66.5 to 69.5%, even more preferably 67.0 to 69.0%, and particularly preferably 67.0 to 68.5%.

[0018] Based on previous findings, the diffuse reflectance of KMF is related to the state of Mn in KMF, such as the valence of Mn in KMF and the ligand of Mn in KMF. Although the details are unclear, the state of Mn in KMF is inherited by the manganese-containing fluoride phosphor produced using that KMF. Therefore, it is thought that by producing a manganese-containing fluoride phosphor using KMF with a diffuse reflectance within a specific range (i.e., Mn in a specific state), it is possible to produce a manganese-containing fluoride phosphor with good luminescence properties.

[0019] The KMF powder of this embodiment can be produced through an appropriate manufacturing process using appropriate materials in appropriate amounts. 550 It may not be possible to produce KMF powder with a % of 66.0 to 70.0%. The details of the appropriate materials, their amounts, and the appropriate manufacturing process will be explained in detail later in the Examples, but a brief description of the "appropriate manufacturing process" will be given below. In the production of KMF, a step of adding hydrogen peroxide to an aqueous solution to precipitate KMF can be carried out. In this step, it is preferable to cool the aqueous solution to preferably 0 to 30°C, more preferably 5 to 15°C, or to add hydrogen peroxide dropwise over a certain period of time. If such cooling conditions or addition conditions are not adopted, ρd 550 It may not be possible to produce KMF powder with a % of 66.0 to 70.0%.

[0020] The KMF powder of this embodiment will now be described.

[0021] For the KMF powder of this embodiment, the diffuse reflectance ρd of light with a wavelength of 310 nm 310 is preferably 16.0 to 25.0%, more preferably 17.0 to 24.0%, and even more preferably 17.9 to 23.1%. For the KMF powder of this embodiment, the diffuse reflectance ρd of light with a wavelength of 455 nm 455is preferably 9.0 to 15.0%, more preferably 9.5 to 14.0%, and even more preferably 10.0 to 13.5%. Also, ρd 310 / ρd 455 The value of is preferably 1.60 or more, more preferably 1.60 to 1.90, and even more preferably 1.70 to 1.80. The diffuse reflectance of KMF may reflect the state of Mn and other elements in KMF. KMF powder having the above-mentioned diffuse reflectance or ratio can be preferably used for producing KSF phosphor.

[0022] The average particle size of the KMF particles in the KMF powder of this embodiment is, for example, 15 to 100 μm, preferably 30 to 85 μm, and more preferably 35 to 70 μm. The average particle size can be determined, for example, by measuring the diameter of particles (primary particles) that are free of agglomerates or overlaps in an image of KMF powder taken with an electron microscope, for as many particles as possible (at least 50, preferably 100), and then averaging the results. If the outline of the primary particle is not circular, the circle-equivalent diameter can be used as the diameter of the primary particle.

[0023] <Method for manufacturing potassium hexafluoromanganate (KMF) powder> The KMF powder of this embodiment preferably comprises: a first step of adding a potassium source to an aqueous solution of hydrogen fluoride and stirring the mixture to obtain a first liquid; a second step of adding a Mn-containing raw material to the first liquid and stirring the mixture to obtain a second liquid; a third step of adding hydrogen peroxide to the second liquid and stirring to obtain a precipitate of potassium hexafluoromanganate; It can be produced by a series of steps including the steps of: Here, the liquid temperature in the third step is preferably 0 to 30°C, more preferably 5 to 15°C, so that ρd 550 It is easy to produce KMF powder with a % of 66.0 to 70.0%.

[0024] The first to third steps will be explained below.

[0025] ·1st process 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, and may be a saturated concentration. The potassium source preferably contains KHF2. KHF2 may be used alone as the potassium source. Potassium sources other than KHF2 include KF and KF·2H2O. The amount of potassium source (preferably KHF2) added in the first step can be, for example, 0.08 to 0.18 mol, preferably 0.08 to 0.15 mol, more preferably 0.08 to 0.09 mol relative to 1 mol of HF in the aqueous solution. From another perspective, the potassium ion concentration of the first liquid obtained in the first step is adjusted to, for example, 1.80 to 5.60 mol / L, preferably 1.80 to 4.15 mol / L, and more preferably 1.80 to 1.84 mol / L. In the first step, the potassium source is usually sufficiently dissolved in an aqueous solution of hydrogen fluoride. It is preferable that the first liquid does not contain any undissolved residue immediately before the second step.

[0026] ·Second process The total amount of Mn atoms in the Mn-containing raw material added in the second step can be adjusted appropriately, taking into account the final composition of the KMF. In the second step, the Mn-containing raw material may be added to the first liquid until it no longer dissolves (i.e., until it reaches saturation). The amount of Mn-containing raw material added is preferably such that the Mn atom concentration in the second liquid obtained in the second step is 0.07 to 0.17 mol / L. Note that if the amount of Mn atoms is increased beyond this amount, the Mn source may remain undissolved, leading to a decrease in properties. Note also that if the amount of Mn atoms is reduced beyond this amount, the resulting KMF concentration will be low, preventing precipitation and resulting in a decrease in yield.

[0027] Examples of Mn-containing raw materials include hexafluoromanganates, permanganates, oxides (excluding permanganates), fluorides (excluding hexafluoromanganates), chlorides, sulfates, and nitrates. From the viewpoints of availability and reactivity, the Mn-containing raw material preferably includes KMnO4.

[0028] In the second step, the Mn-containing raw material is usually dissolved sufficiently in the first liquid. It is preferable that the second liquid does not contain any undissolved material immediately before the third step.

[0029] ·3rd process In the third step, hydrogen peroxide is added to the second liquid and stirred. This allows potassium hexafluoromanganate to precipitate. According to the inventors' findings, it is preferable to appropriately control the temperature of the second liquid and the method of adding hydrogen peroxide. As will be understood from the examples and comparative examples below, the state of the precipitated KMF varies depending on the precipitation conditions.

[0030] In this embodiment, it is preferable to control (by cooling, etc.) the liquid temperature in the third step to preferably 0 to 30° C., more preferably 5 to 15° C. Although the details are unclear, the inventors speculate that if the liquid temperature is not too low, the precipitation of KMF containing excess oxygen atoms is suppressed, and if the liquid temperature is not too high, a sufficiently fast precipitation rate is easily obtained.

[0031] It is preferable to gradually add an appropriate amount of hydrogen peroxide dropwise rather than all at once. Dropwise addition can be carried out using a burette or the like. As an example, the preferable amount of hydrogen peroxide is determined by the ratio of the amount of hydrogen peroxide solution to the amount of Mn dissolved in the second liquid (= amount of KMnO4), i.e., H2O 2mol / KMnO 4mol It is preferable to adjust the amount of hydrogen peroxide to be added so that the ratio is 1.00 to 1.55. Furthermore, the preferred dropping speed is, for example, 0.07 to 0.14 g / s when the volume of the second liquid is about 1 to 2 L.

[0032] Just to be clear, in order to grow KMF crystals appropriately, it is preferable to continue stirring and temperature control for a certain period of time (for example, up to 1 hour) even after the addition (dropping) of hydrogen peroxide is completed. By adopting appropriate deposition conditions, ρd 550 It is easy to obtain KMF powder with a KMF content of 66.0 to 70.0%.

[0033] The KMF precipitated in the third step is usually allowed to settle sufficiently by leaving the container to stand. It is then preferably washed, filtered, dried, and sieved to remove coarse particles. Methanol is preferably used for washing.

[0034] The fact that the precipitated substance has a composition expressed as K2MnF6 can be confirmed through various analytical methods. Specifically, potassium and manganese can be quantitatively analyzed by ICP-MS. Fluorine can be analyzed by ion chromatography. In other words, these measurements can confirm that the composition is expressed as K2MnF6.

[0035] <Manufacturing method of manganese-containing fluoride phosphor, and manganese-containing fluoride phosphor> By using the above-mentioned KMF powder as a raw material, a manganese-containing fluoride phosphor (preferably a KSF phosphor) can be produced.

[0036] The manganese-containing fluoride phosphor can be produced, for example, by the following procedure. Process A: Add KHF2 to an aqueous solution of hydrogen fluoride and stir to obtain Liquid A Process B: Add KMF and Si-containing raw materials to liquid A and stir to obtain liquid B. Process C: Adding KMF to Liquid B in one or more batches and stirring to obtain Liquid C

[0037] The concentration of the aqueous hydrogen fluoride solution in step A 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.

[0038] The amount of KHF2 added is preferably adjusted so that the potassium ion concentration in liquid A obtained in step A is appropriate. Specifically, the amount of KHF2 added is adjusted so that the potassium ion concentration in liquid A is preferably 1.83 to 2.93 mol / L, more preferably 2.01 to 2.19 mol / L, and even more preferably 2.07 to 2.13 mol / L. The total amount of KMF added in steps B and C may be adjusted appropriately taking into consideration the final composition. For example, the total amount of KMF may be preferably 0.01 to 0.10 mol, more preferably 0.05 to 0.09 mol, per 1 mol of Si atoms in the Si-containing raw material in step B.

[0039] Examples of Si-containing raw materials include silicon dioxide, K2SiF6, H2SiF6, etc. 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.

[0040] Typically, fluoride phosphor particles are precipitated in step C. The precipitated fluoride phosphor particles can be obtained by leaving liquid C to settle and then removing the supernatant. The obtained fluoride phosphor particles are preferably washed, dried, and sieved to remove coarse particles. Methanol is preferably used for washing.

[0041] For other circumstances not specified above when producing a fluoride phosphor, known techniques may be referred to or trial and error may be carried out as appropriate. An example of known techniques that can be used as reference is International Publication No. 2017 / 057671.

[0042] The luminescence characteristics of the obtained manganese-containing fluoride phosphor can be further improved by having an appropriate particle size distribution. The cumulative 50% value (median value) in the volume-based particle size distribution curve of the manganese-containing fluoride phosphor is defined as D. 50 When D 50 is preferably 10 to 50 μm, more preferably 20 to 40 μm. 50 A moderate value of may result in, for example, a higher internal or external quantum efficiency.

[0043] From another perspective, the cumulative 50% value (median value) in the volume-based particle size distribution curve of the manganese-containing fluoride phosphor 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 1.20, more preferably 0.70 to 1.10. (D 90 -D 10 ) / D 50 The value of can be interpreted as an index that quantitatively indicates whether the particle size distribution is broad or sharp. (D 90 -D 10 ) / D 50 Fluoride phosphors with a value that is not too large, that is, with a moderately sharp particle size distribution, tend to have excellent light-emitting properties because they do not contain many ultrafine particles or coarse particles that tend to reduce quantum efficiency. As the inventors have found, as will be described later, in the production of a fluoride phosphor, by appropriately controlling the timing and number of times that a Mn-containing raw material is added to an aqueous solution, it is possible to obtain a fluoride phosphor having a high purity (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.

[0044] 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.

[0045] <Composite and Light-Emitting Device> A composite comprising the manganese-containing fluoride phosphor obtained as described above and a sealing material for sealing it is preferably used as a wavelength conversion member in a light emitting device, for example. That is, a light emitting device can be configured by a light emitting element that emits excitation light and the above composite that converts the wavelength of the excitation light.

[0046] An example of the composite and the light emitting device will be described below with reference to FIG.

[0047] FIG. 1 is a schematic diagram of a light emitting device 1. As shown in FIG. 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 bottom 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 a manganese-containing fluoride phosphor.

[0048] The composite 10 can be composed of the above-mentioned manganese-containing fluoride phosphor and a sealing material that seals the phosphor powder. As the encapsulant, for example, various curable resin materials (materials that are cured by heat and / or light) can be used. Any curable resin material can be used as long as it is sufficiently transparent and can provide the optical properties required for displays and lighting devices. Examples of the sealing material include, for example, 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 from the viewpoints of high transparency and excellent heat resistance. In addition, examples of the sealing material also include epoxy resin materials and urethane resin materials. The amount of the manganese-containing fluoride phosphor in the composite 10 is, for example, 10 to 70% by mass, preferably 25 to 55% by mass.

[0049] The size and shape of the light-emitting element 20 are not particularly limited. Depending on the use of the light-emitting device 1, the light-emitting element 20 can have any size and shape.

[0050] As described above, the embodiments of the present invention have been described, but these are examples of the present invention, and various configurations other than those described above can be adopted. Further, the present invention is not limited to the above-described embodiments, and modifications, improvements, etc. within the range that can achieve the object of the present invention are included in the present invention.

Examples

[0051] Embodiments of the present invention will be described in detail based on examples and comparative examples. Just to be on the safe side, the present invention is not limited only to the examples.

[0052] <Production of KMF powder> KMF powder was obtained by the following procedure. Except for the following third step, it was carried out at room temperature. (1) First step 1100 mL of a 55% by mass hydrofluoric acid aqueous solution was placed in a Teflon (registered trademark) beaker. 495 mL of water was added to this hydrofluoric acid aqueous solution and stirred to dilute the aqueous solution. 227 g of a potassium source: KHF2 was added to this aqueous solution, and it was stirred for 5 minutes at a rotation speed of 350 rpm using a magnetic stirrer. Thereby, a first liquid was obtained. (2) Second step 18 g of KMnO4 was added to the above first liquid, and it was stirred for 35 minutes at a rotation speed of 350 rpm using a magnetic stirrer. Thereby, a second liquid was obtained. (5) Step 3 While stirring the second liquid with a magnetic stirrer at a rotational speed of 350 rpm, 16.8 g of 35% by mass hydrogen peroxide solution was dropped at the speed shown in Table 1 using a burette. Stirring with the magnetic stirrer continued even after the dropping ended. Stirring was continued for 10 minutes after the dropping of the hydrogen peroxide solution ended. At this time, the liquid temperature was maintained at the temperature shown in Table 1. Potassium hexafluoromanganate was precipitated by this Step 3. (6) Post-treatment After the completion of Step 3, the container was allowed to stand still to sufficiently precipitate the precipitated potassium hexafluoromanganate. Thereafter, washing with methanol, filtration, drying, removal of coarse particles by sieving, etc. were performed.

[0053] Regarding that the powder obtained through the above (6) post-treatment was indeed potassium hexafluoromanganate, it was confirmed based on X-ray diffraction measurement, etc.

[0054] <Measurement of Diffuse Reflectance of KMF Powder> The diffuse reflectance of the obtained KMF powder was measured using an ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, product name: V-550). Specifically, after performing baseline correction with a standard reflector (Spectralon), a solid sample holder made of PMMA filled with KMF powder was attached to a predetermined position of the apparatus, and the diffuse reflectance was measured in the wavelength range of 22~850 nm.

[0055] Table 1 shows the production conditions of KMF powder (dropping time of hydrogen peroxide solution and liquid temperature in Step 3) and the measurement results of the diffuse reflectance of KMF powder.

[0056]

Table 1

[0057] <Average Particle Size of Particles in KMF Powder> The powders of KMF in Examples 1 to 3 were photographed with an electron microscope. Based on the photographed images, it was confirmed that the average particle size of the KMF powders in Examples 1 to 3 was within the range of 35 to 70 μm.

[0058] <Production of KSF Phosphor> Using the KMF powder obtained above (any one of Examples 1 to 3, Comparative Examples 1 and 2), a KSF phosphor was produced by the following procedure. (1) At room temperature, 1260 mL of an HF aqueous solution with a concentration of 55% by mass was placed in a beaker made of Teflon (registered trademark), 189 g of KHF₂ was added, and it was sufficiently stirred using a magnetic stirrer. Thereby, a uniform solution (the first solution) was obtained. (2) The above beaker was immersed in the antifreeze in a cooling bath containing antifreeze, and cooling was started while continuing stirring. Then, when the first solution reached -7°C, 43.2 g of SiO₂ and 2.4 g of KMF were simultaneously added to the first solution. The time of this addition was taken as time t = 0. In this way, the second solution was obtained. (3) While continuing stirring and cooling, 2.4 g of KMF was sequentially added to the second solution at t = 45 s, 2.4 g of KMF at t = 90 s, and 2.4 g of KMF at t = 135 s. Then, stirring was terminated at the time point of t = 1500 s (25 minutes). (4) After the stirring in (3) above was completed, the solution was allowed to stand to sufficiently precipitate the yellow solid content. Then, the supernatant was removed, the yellow solid content was washed with hydrofluoric acid with a concentration of about 24% by mass, and then washed with methanol. The washed solid content was filtered to separate and recover the solid content, and further by drying treatment, the residual methanol was evaporated and removed. After the drying treatment, using a nylon sieve with a mesh size of 75 μm, only the yellow powder that passed through this sieve was classified and recovered.

[0059] <00003​​​​30 mL of ethanol was weighed into a 50 mL beaker, and 0.03 g of KSF phosphor was added thereto. Next, the container was set in a homogenizer (manufactured by Nippon Seiki Co., Ltd., product name US-150E) whose output had been adjusted to "Altitude: 100%" in advance, and pretreatment was carried out for 3 minutes. Thus, a dispersion of phosphor particles was obtained. Using a laser diffraction / scattering particle size distribution analyzer (manufactured by Microtrac BEL Corporation, product name MT3300EXII), a volume-based particle size distribution curve was obtained for the dispersion prepared as described above. Then, from the obtained curve, D 50 、D 10 and D 90 were determined.

[0060] (Measurement of Diffuse Reflectance) The diffuse reflectance of the KSF phosphor was measured in the same manner as in <Measurement of Diffuse Reflectance of the Above-mentioned KMF Powder>. The diffuse reflectance of light with a wavelength of 455 nm is described in the table shown later.

[0061] (Evaluation of Luminescence Characteristics) A standard reflector with a reflectance of 99% (manufactured by Labsphere, product name Spectralon) was set at the side opening (φ10 mm) of an integrating sphere (φ60 mm). Monochromatic light having a wavelength of 455 nm, which was spectrally separated from a light-emitting light source (Xe lamp), was introduced into this integrating sphere through an optical fiber. Then, the spectrum of the reflected light was measured with a spectrophotometer (manufactured by Otsuka Electronics Co., Ltd., product name QE-2000). At this time, 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 KSF phosphor particles so that the surface was smooth was set at the opening of the integrating sphere. Then, the phosphor particles were irradiated with monochromatic light having a wavelength of 455 nm. Then, the spectra of the excitation reflected light and fluorescence were measured with a spectrophotometer. From the obtained spectral data, the number of excitation reflected photons (Qref) and the number of fluorescence photons (Qem) were calculated. The number of excitation reflected photons was calculated in the same wavelength range as the number of excitation photons, and the number of fluorescence photons was calculated in the wavelength range of 465 to 800 nm. The following three characteristics were calculated from the three types of photon counts obtained. Absorption rate (%): {(Qex-Qref) / Qex} x 100 Internal quantum efficiency (%): {Qem / (Qex-Qref)}×100 External quantum efficiency (%): (Qem / Qex) x 100

[0062] The measurement / evaluation results for the KSF phosphor are summarized in the table below.

[0063] [Table 2]

[0064] As can be seen from Tables 1 and 2, by using the KMFs of Examples 1 to 3, which have a diffuse reflectance of light with a wavelength of 550 nm in the range of 66.0 to 70.0%, as raw materials for producing KSF phosphors, it was possible to produce fluoride phosphors (KSF phosphors) with good luminescence properties, with an internal quantum efficiency of 83.0% or more and an external quantum efficiency of 66.0% or more. In contrast, the fluoride phosphors (KSF phosphors) produced using the KMF of Comparative Examples 1 and 2, which had a diffuse reflectance of less than 66.0% for light with a wavelength of 550 nm, as raw materials had internal quantum efficiencies of less than 83.0% and external quantum efficiencies of less than 66.0%. In other words, the light-emitting properties of the produced fluoride phosphors (KSF phosphors) were inferior to those when the KMF of Examples 1 to 3 were used as raw materials for producing KSF phosphors. [Explanation of symbols]

[0065] 1. Light-emitting device 10 Complex 20 Light-emitting element

Claims

1. Diffuse reflectance ρd of light with a wavelength of 550 nm ５５０ A powder of potassium hexafluoromanganate, wherein the content of manganese is 66.0 to 70.0%.

2. The potassium hexafluoromanganate powder according to claim 1, The diffuse reflectance of light with a wavelength of 310 nm is ρd ３１０ The diffuse reflectance of light with a wavelength of 455 nm is ρd ４５５ When this is the case, ρd ３１０ / ρd ４５５ A powder of potassium hexafluoromanganate having a value of 1.60 or more.

3. The potassium hexafluoromanganate powder according to claim 1 or 2, Diffuse reflectance ρd of light with a wavelength of 310 nm ３１０ A powder of potassium hexafluoromanganate, wherein the content of manganese is 16.0 to 25.0%.

4. The potassium hexafluoromanganate powder according to claim 1 or 2, Diffuse reflectance ρd of light with a wavelength of 455 nm ４５５ A powder of potassium hexafluoromanganate, wherein the content of manganese is 9.0 to 15.0%.

5. The potassium hexafluoromanganate powder according to claim 1 or 2, A powder of potassium hexafluoromanganate having an average particle size of 35 to 70 μm as determined from an electron microscope image.

6. A method for producing a manganese-containing fluoride fluorescent material, using the potassium hexafluoromanganate powder according to claim 1 or 2 as a raw material.

7. A manganese-containing fluoride phosphor obtained by the method for producing a manganese-containing fluoride phosphor according to claim 6.

8. A composite comprising the manganese-containing fluoride phosphor according to claim 7 and an encapsulant that encapsulates the manganese-containing fluoride phosphor.

9. A light emitting device comprising: a light emitting element that emits excitation light; and the composite according to claim 8 that converts the wavelength of the excitation light.

10. A method for producing the potassium hexafluoromanganate powder according to claim 1 or 2, comprising: a first step of adding a potassium source to an aqueous solution of hydrogen fluoride and stirring the mixture to obtain a first liquid; a second step of adding a Mn-containing raw material to the first liquid and stirring the mixture to obtain a second liquid; a third step of adding hydrogen peroxide to the second liquid and stirring the mixture to obtain a precipitate of potassium hexafluoromanganate; Including, The method for producing potassium hexafluoromanganate powder, wherein the liquid temperature in the third step is 0 to 30°C.

11. A method for producing the potassium hexafluoromanganate powder according to claim 10, comprising: The potassium source is KHF ２ A method for producing potassium hexafluoromanganate powder, comprising:

12. A method for producing the potassium hexafluoromanganate powder according to claim 10 or 11, comprising: The Mn-containing raw material is KMnO ４ A method for producing potassium hexafluoromanganate powder, comprising:

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