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• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent materials, e.g. electroluminescent or chemiluminescent
  • C09K11/08—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent materials, e.g. electroluminescent or chemiluminescent
  • C09K11/08—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials
  • C09K11/64—Luminescent materials, e.g. electroluminescent or chemiluminescent containing inorganic luminescent materials containing aluminium

Definitions

• the present invention relates to a method for producing phosphor particles.
• Patent Document 1 describes a method for producing SrLiAl 3 N 4 : Eu (SLAN phosphor) (claim 1, paragraph 0113, etc. of Patent Document 1).
• the present inventor has found that the emission characteristics of the phosphor such as the internal quantum efficiency may be lowered due to the different phase generated in the manufacturing process of the phosphor particles.
• the type of flux to be mixed with the raw material mixture of phosphor particles was appropriately selected, and acid treatment using a mixed solution containing acid and alcohol was performed during the manufacturing process.
• phosphor particles with excellent internal quantum efficiency can be realized, and have completed the present invention.
• LiF functions as an appropriate flux, so that grain growth can be promoted and the optical properties of the phosphor particles can be improved, and LiF was used by applying an acid treatment. This is thought to be because it is possible to remove the heterogeneous phase that sometimes occurs.
• a method for producing fluorescent particles having the above is provided.
• the method for producing the fluorescent particles is as follows: at least one element M 1 selected from the group consisting of Sr, Mg, Ca and Ba, at least one element M 2 selected from the group consisting of Li and Na, Eu and Fluorescent particles (fluorescent particles) having a composition containing at least one element M 3 , Al, and N selected from the group consisting of Ce are produced.
• the method for producing the phosphor particles can include a mixing step, a firing step, a pulverization step, an acid treatment step, a hydrofluoric acid treatment step, and a heat treatment step. Each step will be described in detail.
• a raw material mixture containing each element constituting the composition of the phosphor and LiF as a flux are mixed to obtain a mixture.
• each raw material weighed so as to obtain the desired phosphor particles may be mixed to obtain a powdery mixture.
• the method of mixing the raw materials is not particularly limited, but for example, there is a method of sufficiently mixing using a mixing device such as a mortar, a ball mill, a V-type mixer, and a planetary mill. It is appropriate to handle strontium nitride, lithium nitride, etc., which react violently with moisture and oxygen in the air, in a glove box whose interior is replaced with an inert atmosphere or by using a mixing device.
• a mixing device such as a mortar, a ball mill, a V-type mixer, and a planetary mill. It is appropriate to handle strontium nitride, lithium nitride, etc., which react violently with moisture and oxygen in the air, in a glove box whose interior is replaced with an inert atmosphere or by using a mixing device.
• the amount of M 1 charged when the molar ratio of Al is 3 is 1.10 or more in terms of molar ratio.
• the charge amount of M 1 it is possible to prevent the shortage of M 1 in the phosphor due to volatilization of M 1 during the firing process, and it is difficult for defects to occur in M 1. , Crystalline is kept good. As a result, a narrow-band fluorescence spectrum can be obtained, and it is presumed that the emission intensity can be increased.
• the amount of M 1 charged when the molar ratio of Al is 3 is 1.20 or less in terms of molar ratio.
• Each raw material used in the mixing step can include one or more selected from the group consisting of a simple substance of a metal element contained in the composition of a phosphor and a metal compound containing the metal element.
• the metal compound include nitrides, hydrides, fluorides, oxides, carbonates, chlorides and the like. Of these, nitrides are preferably used as the metal compound containing M 1 and M 2 from the viewpoint of improving the emission intensity of the phosphor.
• a metal compound containing M 1, Sr 3 N 2, SrN 2, etc. SrN the like.
• the metal compound containing M 2 include Li 3 N and Li N 3 .
• the metal compound containing M 3 include Eu 2 O 3 , Eu N, and Eu F 3 .
• the metal compound containing Al include AlN, AlH 3 , AlF 3 , LiAlH 4 and the like.
• the lower limit of the amount of LiF added is, for example, 1% by mass or more, preferably 2% by mass or more, and more preferably 4% by mass or more, based on 100% by mass of the total of LiF and the raw material mixture.
• the upper limit of the amount of LiF added may be, for example, 10% by mass or less, preferably 5% by mass or less, based on 100% by mass of the total of LiF and the raw material mixture.
• the flux LiF may be used alone, or may be used in combination with other fluxes.
• the content of LiF in the flux used in the mixing step is, for example, 50% by mass or more, preferably 80% by mass or more, and more preferably 100% by mass.
• the firing step fires the above-mentioned mixture.
• the mixture filled inside the firing container may be fired.
• the firing container preferably has a structure that can improve airtightness.
• the firing vessel is preferably made of a material that is stable under high temperature atmospheric gas and does not easily react with the mixture of raw materials and its reaction products.
• a vessel made of boron nitride or carbon, molybdenum or tantalum It is preferable to use a container made of a refractory metal such as molybdenum or tungsten.
• an atmospheric gas of non-oxidizing gas such as argon, helium, hydrogen, and nitrogen.
• the lower limit of the firing temperature in the firing step is preferably 900 ° C. or higher, more preferably 1000 ° C. or higher, and even more preferably 1100 ° C. or higher.
• the upper limit of the firing temperature is preferably 1500 ° C. or lower, more preferably 1400 ° C. or lower, and even more preferably 1300 ° C. or lower.
• Type of firing atmosphere gas As the type of firing atmosphere gas in the firing step, for example, a gas containing nitrogen as an element can be preferably used. Specific examples include nitrogen and / or ammonia, with nitrogen being particularly preferred. Similarly, an inert gas such as argon or helium can also be preferably used.
• the firing atmosphere gas may be composed of one type of gas or a mixed gas of a plurality of types of gases.
• the pressure of the firing atmosphere gas is selected according to the firing temperature, but is usually in a pressurized state in the range of 0.1 MPa ⁇ G or more and 10 MPa ⁇ G or less.
• the raw material mixture (calcined product) after the firing step is pulverized to obtain a pulverized product.
• the state of the fired product obtained by the firing process varies from powdery to lumpy depending on the raw material composition and firing conditions.
• the fired product can be made into a powder of a predetermined size.
• the member of the device that comes into contact with the fired product is made of ceramics such as silicon nitride, alumina, and sialon in order to prevent impurities derived from the treatment from being mixed.
• the average particle size of the pulverized product may be adjusted so that the average particle size of the phosphor particles is 5 ⁇ m or more and 30 ⁇ m or less.
• the phosphor particles have excellent absorption efficiency and luminous efficiency of excitation light, and therefore can be suitably used for LEDs and the like.
• the pulverized product is acid-treated with a mixed solution containing an acid and an alcohol.
• the acid treatment may be added to the pulverized product in a mixed solution containing the acid and alcohol, or the acid may be added to the pulverized product in alcohol.
• the mixed solution may be allowed to stand during the acid treatment, or may be stirred under appropriate conditions.
• decantation solid-liquid separation treatment
• Decantation may be performed once or more than once. As a result, the acid can be washed and removed from the pulverized product. Then, the pulverized product is filtered and dried.
• the mixed solution may contain an aqueous solvent.
• an aliphatic alcohol specifically, MeOH, EtOH, IPA and the like are used.
• the alcohol and the acid may be mixed so that the concentration of the acid in the mixed solution is, for example, 0.1% by mass to 5% by mass, preferably 0.5% by mass to 3% by mass.
• impurity elements contained in the raw material, impurity elements derived from the firing container, different phases generated in the firing process, and impurity elements mixed in the crushing process can be dissolved and removed. That is, the acid treatment can wash foreign substances and the like. As a result, the internal quantum efficiency of the phosphor can be improved.
• the pulverized product may be dispersed and immersed in a mixed solution containing an acid and an alcohol for, for example, 0.5 hours or more and 5 hours or less.
• hydrofluoric acid treatment process In the hydrofluoric acid treatment, the pulverized product after the acid treatment step is subjected to the hydrofluoric acid treatment.
• an aqueous solution containing hydrogen fluoride is preferably used as the compound containing a fluorine element.
• hydrofluoric acid treatment for example, a pulverized product may be added to the hydrofluoric acid.
• the lower limit of the concentration of hydrofluoric acid (HF) in hydrofluoric acid is preferably 20% by mass or more, more preferably 25% by mass or more, still more preferably 30% by mass or more.
• the upper limit of the concentration of hydrogen fluoride in hydrofluoric acid is preferably 40% by mass or less, more preferably 38% by mass or less, still more preferably 35% by mass or less.
• a coating portion containing (NH 4 ) 3 AlF 6 can be formed on at least a part of the outermost surface of the particles containing the phosphor.
• concentration of hydrogen fluoride it is possible to prevent the reaction between the particles and hydrofluoric acid from becoming too violent.
• the type of acid and solvent in the acid treatment step, the acid concentration, the hydrofluoric acid concentration in the hydrofluoric acid treatment step, the hydrofluoric acid treatment time, the heating temperature and the heating time in the heat treatment step performed after the hydrofluoric acid treatment.
• Heat treatment process In the heat treatment, the pulverized product after the hydrofluoric acid treatment is heated in the air.
• the lower limit of the heating temperature in the heat treatment step is preferably 220 ° C. or higher, more preferably 250 ° C. or higher.
• the upper limit of the heating temperature is preferably 380 ° C. or lower, more preferably 350 ° C. or lower, and even more preferably 330 ° C. or lower.
• the heating temperature to the above upper limit or less, the crystal structure of the phosphor can be maintained well and the emission intensity can be increased.
• the lower limit of the heating time is preferably 1 hour or more, more preferably 1.5 hours or more, still more preferably 2 hours or more.
• the upper limit of the heating time is preferably 6 hours or less, more preferably 5.5 hours or less, and even more preferably 5 hours or less.
• the heat treatment step is preferably carried out in the air or in a nitrogen atmosphere. According to this, the target substance can be produced without the substance itself in the heating atmosphere hindering the above reaction formula (1).
• the phosphor particles of the present embodiment will be described.
• the phosphor particles of the present embodiment may be composed of surface-coated phosphor particles containing particles containing a phosphor and a coating portion that covers the surface of the particles.
• the phosphor contained in the phosphor particles has a composition represented by the general formula M 1 a M 2 b M 3 c Al 3 N 4-d Od .
• M 1 is one or more elements selected from Sr, Mg, Ca and Ba
• M 2 is one or more elements selected from Li and Na
• M 3 is selected from Eu and Ce. It is one or more elements.
• a, b, c, 4-d, and d indicate the molar ratio of each element.
• A, b, c, and d in the general formula satisfy each of the following formulas. 0.850 ⁇ a ⁇ 1.150 0.850 ⁇ b ⁇ 1.150 0.001 ⁇ c ⁇ 0.015 0 ⁇ d ⁇ 0.40 0 ⁇ d / (a + d) ⁇ 0.30
• M 1 is one or more elements selected from Sr, Mg, Ca and Ba, and preferably contains at least Sr.
• the lower limit of the molar ratio a of M 1 is preferably 0.850 or more, more preferably 0.950 or more.
• the upper limit of the molar ratio a of M 1 is preferably 1.150 or less, more preferably 1.100 or less, and even more preferably 1.050 or less.
• M 2 is one or more elements selected from Li and Na, preferably containing at least Li.
• Molar ratio lower limit of b of M 2 is preferably not less than 0.850, more preferably not less than 0.950.
• the upper limit of the molar ratio b of M 2 is preferably 1.150 or less, more preferably 1.100 or less, more preferably 1.050 or less.
• the molar ratio a of M 2 is in the above range, it is possible to improve the crystal structure stability.
• M 3 is an activator added to the parent crystal, that is, an element constituting the emission center ion of the phosphor, and is one or more elements selected from Eu and Ce. M 3 can be selected according to the required emission wavelength, and preferably contains at least Eu.
• the lower limit of the molar ratio c of M 3 is preferably 0.001 or more, and more preferably 0.005 or more.
• the upper limit of the molar ratio c of M 3 is preferably 0.015 or less, more preferably 0.010 or less.
• the lower limit of the molar ratio d of oxygen (O) is preferably 0 or more, more preferably 0.05 or more.
• the upper limit of the molar ratio d of oxygen is preferably 0.40 or less, more preferably 0.35 or less.
• the lower limit of the molar ratio of M 1 and oxygen that is, the value of d / (a + d) calculated from a and d is preferably 0 or more, and more preferably 0.05 or more.
• the upper limit of the value of d / (a + d) is preferably less than 0.30, more preferably 0.25 or less.
• the coating portion constitutes at least a part of the outermost surface of the particles containing the above-mentioned phosphor.
• the coating contains a fluorine-containing compound containing a fluorine element and an aluminum element.
• the fluorine-containing compound it is preferable that the fluorine element and the aluminum element are directly covalently bonded, and more specifically, the fluorine-containing compound is one or both of (NH 4 ) 3 AlF 6 and AlF 3. Is preferably included.
• the fluorine-containing compound may be composed of a single compound containing a fluorine element and an aluminum element.
• the coating portion containing the fluorine-containing compound constitutes at least a part of the outermost surface of the particles containing the phosphor, the moisture resistance of the phosphor constituting the particles can be improved. From the viewpoint of further improving the moisture resistance of the phosphor, it is more preferable that the coating portion contains AlF 3 .
• the mode of the covering portion is not particularly limited.
• Examples of the mode of the coating portion include a mode in which a large number of particulate fluorine-containing compounds are distributed on the surface of the particles containing the phosphor, and a mode in which the fluorine-containing compound continuously covers the surface of the particles containing the phosphor. Can be mentioned.
• the coating may be configured to cover part or all of the particle surface.
• the diffuse reflectance with respect to light irradiation having a wavelength of 300 nm is, for example, 56% or more, preferably 65% or more, and more preferably 70% or more. Further, in the phosphor particles, the diffuse reflectance with respect to light irradiation at the peak wavelength of the fluorescence spectrum is, for example, 80% or more, preferably 83% or more, and more preferably 85% or more. By providing such a diffuse reflectance, the luminous efficiency is further increased and the emission intensity is improved.
• the phosphor particles When excited with blue light having a wavelength of 455 nm, the phosphor particles may be configured so that the peak wavelength is in the range of, for example, 640 nm or more and 670 nm or less, and the half width thereof satisfies, for example, 45 nm or more and 60 nm or less. By providing such characteristics, excellent color rendering and color reproducibility can be expected.
• the phosphor particles When excited with blue light having a wavelength of 455 nm, the phosphor particles may be configured such that the x value in the CIE-xy chromaticity diagram satisfies, for example, 0.680 ⁇ x ⁇ 0.735. By providing such characteristics, excellent color rendering and color reproducibility can be expected. If the x value is 0.680 or more, red emission with good color purity can be further expected, and if the x value is 0.735 or more, it exceeds the maximum value in the CIE-xy chromaticity diagram, so the above range is satisfied. Is preferable.
• the light emitting device according to the present embodiment includes phosphor particles and a light emitting element.
• the phosphor particles in addition to the phosphor particles, fluorescent particles having other emission colors may be used in combination.
• the phosphor particles having other emission colors include blue emission phosphor particles, green emission phosphor particles, yellow emission phosphor particles, orange emission phosphor particles, and red phosphor.
• Ca 3 Sc 2 Si 3 O 12 : Ce, CaSc 2 O 4 : Ce, ⁇ -SiAlON: Eu, Y 3 Al 5 O 12 : Ce, Tb 3 Al 5 O 12 : Ce, (Sr, Ca, Ba) 2 SiO 4 : Eu, La 3 Si 6 N 11 : Ce, ⁇ -SiAlON: Eu, Sr 2 Si 5 N 8 : Eu and the like can be mentioned.
• the other phosphor particles are not particularly limited, and can be appropriately selected according to the brightness, color rendering properties, etc. required for the light emitting device. By mixing the phosphor particles and the phosphor particles of other emission colors, it is possible to realize white at various color temperatures such as neutral white and light bulb color.
• the light emitting device include a lighting device, a backlight device, an image display device, a signal device, and the like.
• the light emitting device By providing the light emitting device with phosphor particles, it is possible to improve the reliability while realizing high light emitting intensity.
• Example 1 5 g of the phosphor powder obtained in the same manner as in Comparative Example 1 was mixed with 500 ml of MeOH (purity 99%) (manufactured by Kokusan Kagaku Co., Ltd.) and 10 ml of nitric acid (HNO 3 concentration 60%) (manufactured by Wako Pure Chemical Industries, Ltd.). After adding to the added mixed solution and stirring for 3 hours, the mixture was neutralized by decantation with MeOH, and then filtered and dried to obtain a phosphor powder.
• MeOH purity 99%
• HNO 3 concentration 60% manufactured by Wako Pure Chemical Industries, Ltd.
• Example 2 The phosphor powder obtained in the same manner as in Comparative Example 1 was added to a mixed solution of EtOH with nitric acid (HNO 3 concentration 60%) (manufactured by Wako Pure Chemical Industries, Ltd.) and stirred for 3 hours.
• the phosphor powder of Example 2 was obtained by the same raw material charge amount and procedure as in Example 1.
• Example 3 The phosphor powder obtained in the same manner as in Comparative Example 1 was added to a mixed solution of IPA containing nitric acid (HNO 3 concentration 60%) (manufactured by Wako Pure Chemical Industries, Ltd.) and stirred for 3 hours.
• the phosphor powder of Example 3 was obtained by the same raw material charge amount and procedure as in Example 1.
• Comparative Example 2 The phosphor powder of Comparative Example 2 was obtained by the same raw material charge amount and procedure as in Example 1 except that SrF 2 was used as the flux instead of LiF.
• the obtained phosphor particles were determined Sr a Li b Eu c Al 3 N 4-d O subscripts a ⁇ d of each element d. Specifically, for Sr, Li, Al and Eu, an ICP emission spectroscopic analyzer (CIROS-120, manufactured by SPECTRO) was used, and for O and N, an oxygen nitrogen analyzer (EMGA-920, manufactured by Horiba Seisakusho) was used. Subscripts a to d were calculated using the analysis results used. The numerical values of a to d of each phosphor particle are shown in Table 1.
• the obtained phosphor particles were evaluated based on the following evaluation items.
• a concave cell filled with a phosphor so as to have a smooth surface is set in the opening of the integrating sphere, monochromatic light having a wavelength of 455 nm is irradiated, and the spectrum of the reflected light of excitation and the fluorescence is spectrophotometer. Measured by meter. From the obtained spectral data, the number of excited reflected light photons (Qref) and the number of fluorescent photons (Qem) were calculated. The number of excited reflected light photons was calculated in the same wavelength range as the number of excited light photons, and the number of fluorescent photons was calculated in the range of 465 to 800 nm.
• the internal quantum efficiency Qem / (Qex-Qref) ⁇ 100 was obtained from the obtained three types of photon numbers.
• the peak wavelength, full width at half maximum, and chromaticity x value were obtained from the fluorescence spectrum obtained by this measurement.
• the chromaticity is calculated according to JIS Z 8724 (color measurement method-light source color-), and the chromaticity coordinates (x, y) are calculated by the calculation method in the XYZ color system defined in JIS Z 8701. did.
• the wavelength range used for calculating the chromaticity coordinates was 550 to 780 nm.
• the diffuse reflectance was measured by attaching an integrating sphere device (ISV-469) to an ultraviolet-visible spectrophotometer (V-550 manufactured by JASCO Corporation). Baseline correction was performed with a standard reflector (Spectralon), and a solid sample holder filled with the obtained phosphor particles was attached, and the diffuse reflectance for light of 300 nm and peak wavelength was measured.

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• 2020
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