Method for producing sialon phosphor powder

Abstract

To provide a method of producing sialon phosphor powder that allows production of sialon phosphor powder with improved emission intensity.SOLUTION: There is provided a method for producing sialon phosphor powder, the method comprising: a step (A) in which a sialon powder (a) with europium solid-dissolved therein is prepared; and a step (B) in which a sialon powder (b) is obtained by performing an annealing treatment on a mixture comprising a europium compound and the sialon powder (a) with europium solid-dissolved therein, wherein the europium compound includes at least one selected from the group consisting of europium oxide, europium halide, europium hydroxide, europium nitride, and europium oxynitride, and in the step (B), the annealing treatment temperature is 1000°C or more and less than 1300°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a sialon phosphor powder. [Background technology]

[0002] As a technique relating to a method for producing a sialon phosphor powder, for example, the technique described in Patent Document 1 can be mentioned.

[0003] Patent Document 1 describes a method for producing a β-sialon phosphor, which includes a first heat-treatment step of heat-treating a mixture containing an aluminum compound, a first europium compound, and silicon nitride to obtain a first heat-treated product, and a second heat-treatment step of heat-treating the first heat-treated product and a second europium compound in a rare gas atmosphere to obtain a second heat-treated product. Patent Document 1 discloses that the method for producing a β-sialon phosphor described therein can provide a method for producing a β-sialon phosphor with excellent luminance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-2278 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides a method for producing a sialon phosphor powder that can provide a sialon phosphor powder with improved luminescence intensity. [Means for solving the problem]

[0006] According to the present invention, there is provided a method for producing a sialon phosphor powder as follows.

[0007] [1] A step (A) of preparing a sialon powder (a) in which europium is solid-dissolved; and (B) a step of annealing a mixture containing a europium compound and the sialon powder (a) in which europium is dissolved to obtain the sialon powder (b), the europium compound includes at least one selected from the group consisting of europium oxide, europium halide, europium hydroxide, europium nitride, and europium oxynitride, The method for producing a sialon phosphor powder, wherein the annealing temperature in the step (B) is 1000°C or higher and lower than 1300°C. [2] The method for producing a sialon phosphor powder according to [1] above, wherein in the step (B), the annealing treatment time is 6 hours or more and 30 hours or less. [3] The method for producing a sialon phosphor powder according to [1] or [2], wherein in step (B), the annealing treatment is carried out in an atmosphere containing at least one gas selected from the group consisting of a rare gas, a reducing gas, and an inert gas. [4] The method for producing a sialon phosphor powder according to any one of [1] to [3] above, wherein the europium compound includes at least one selected from the group consisting of europium oxide and europium halide. [5] The method for producing a sialon phosphor powder according to any one of [1] to [4], wherein in step (B), the amount of the europium compound is 0.05 mass % or more and 2.00 mass % or less, when the total of the sialon powder (a) in which europium is dissolved and the europium compound is 100 mass %. [6] The method for producing a sialon phosphor powder according to any one of [1] to [5] above, wherein the step (A) comprises a step (A-1) of firing a raw material powder mixture containing a raw material powder containing silicon, a raw material powder containing aluminum, and a raw material powder containing europium. [7] The method for producing a sialon phosphor powder according to [6] above, wherein in the step (A-1), the firing temperature is 1700°C or higher and 2500°C or lower. [8] The method for producing a sialon phosphor powder according to any one of [1] to [7] above, further comprising a step (C) of treating the sialon powder (b) with an acid after the step (B). [9] The method for producing a sialon phosphor powder according to any one of [1] to [8] above, wherein the sialon phosphor powder includes a β-sialon phosphor powder.

[10] The method for producing a sialon phosphor powder according to any one of [1] to [9] above, wherein the sialon phosphor powder has an emission peak wavelength of 527.0 nm or more and 551.0 nm or less. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a method for producing a sialon phosphor powder that can produce a sialon phosphor powder with improved luminescence intensity. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described. Numerical ranges "A to B" represent A or more and B or less unless otherwise specified.

[0010] [Manufacturing method of SiAlON phosphor powder] The method for producing a sialon phosphor powder of this embodiment comprises step (A) of preparing sialon powder (a) in which europium is dissolved, and step (B) of obtaining sialon powder (b) by annealing a mixture containing a europium compound and the sialon powder (a) in which europium is dissolved, wherein the europium compound contains at least one selected from the group consisting of europium oxide, europium halide, europium hydroxide, europium nitride, and europium oxynitride, and the annealing temperature in step (B) is 1000°C or higher but lower than 1300°C.

[0011] In this specification, "sialon powder (a) in which europium is dissolved" may be abbreviated to "sialon powder (a)".

[0012] Hereinafter, each step of the method for producing a sialon phosphor powder according to this embodiment will be specifically described.

[0013] <Process (A)> The method for producing a sialon phosphor powder of this embodiment includes a step (A) of preparing a sialon powder (a) in which europium is dissolved as a solid solution.

[0014] In step (A), the method for preparing the sialon powder (a) in which europium is dissolved is not particularly limited, and for example, the sialon powder (a) may be prepared by a known method.

[0015] Step (A) preferably includes a step (A-1) of firing a raw material powder mixture containing a raw material powder containing silicon, a raw material powder containing aluminum, and a raw material powder containing europium.

[0016] The silicon-containing raw material powder contains, for example, at least one selected from the group consisting of silicon nitride and silicon dioxide, and preferably contains silicon nitride.

[0017] The raw material powder containing aluminum includes, for example, at least one selected from the group consisting of aluminum nitride, aluminum oxide, and aluminum hydroxide, and preferably includes at least one selected from the group consisting of aluminum nitride and aluminum oxide.

[0018] The raw material powder containing europium contains, for example, at least one selected from the group consisting of europium oxide, europium nitride, and europium halide, and preferably europium oxide. The europium halide includes, for example, at least one selected from the group consisting of europium fluoride, europium chloride, europium bromide, and europium iodide. In the raw material powder containing europium, the valence of europium may include divalent and trivalent.

[0019] The raw material powder mixture containing silicon, aluminum, and europium is obtained by mixing the raw materials. The mixing method is not particularly limited, but the raw materials may be mixed using, for example, a V-type mixer.

[0020] In the raw material powder mixture, the mixing ratio of each raw material may be adjusted appropriately based on the composition of the target SiAlON phosphor powder.

[0021] In order to further improve the luminescence intensity of the SiAlON phosphor powder, the firing temperature in step (A-1) is preferably 1700°C or higher, more preferably 1750°C or higher, even more preferably 1800°C or higher, even more preferably 1850°C or higher, even more preferably 1900°C or higher, even more preferably 1920°C or higher, and is preferably 2500°C or lower, more preferably 2400°C or lower, even more preferably 2200°C or lower, even more preferably 2100°C or lower.

[0022] The firing time in step (A-1) is not particularly limited, and may be, for example, 1 hour to 240 hours, 2 hours to 100 hours, or 3 hours to 25 hours.

[0023] In the step (A-1), the raw material powder mixture may be fired, for example, in a nitrogen atmosphere.

[0024] The method may further include a second firing step after step (A-1) in which the fired body obtained in step (A-1) is fired. Furthermore, after the second firing step, the firing step may be further performed multiple times. The firing conditions for the second firing step and subsequent steps are not particularly limited, but the preferred ranges are the same as those for step (A-1). When firing in the second firing step or later, a mixture in which a portion of the raw material powder is added to the fired body obtained in the previous step may be fired.

[0025] The sintered body obtained in step (A-1) can be the sialon powder (a) of this embodiment in which europium is solid-dissolved. If a sintering step is further provided after step (A-1), the sintered body obtained in the final sintering step can be the sialon powder (a) of this embodiment in which europium is solid-dissolved. The fired body may be subjected to crushing, sieving, classification, and the like.

[0026] <Process (B)> The method for producing a sialon phosphor powder of this embodiment includes a step (B) of annealing a mixture containing a europium compound and a sialon powder (a) in which europium is solid-dissolved, to obtain a sialon powder (b). In step (B), the europium compound includes at least one selected from the group consisting of europium oxide, europium halide, europium hydroxide, europium nitride, and europium oxynitride.

[0027] The method for producing a sialon phosphor powder according to this embodiment includes step (B), which improves the luminous intensity of the resulting sialon phosphor powder. The reason for this is unclear, but the inventors speculate as follows. The present inventors believe that in conventional methods for producing sialon phosphor powders, europium may be desorbed from the sialon powder (a) during the annealing process, resulting in a decrease in the luminescence intensity of the sialon phosphor powder. Therefore, by annealing the sialon powder (a) in the presence of a europium compound, the desorption of europium from the sialon powder (a) can be suppressed, thereby improving the luminescence intensity of the resulting sialon phosphor powder. More specifically, the present inventors believe that annealing the sialon powder (a) in the presence of a europium compound makes it possible to supply europium derived from the europium compound even if europium from the sialon powder (a) is desorbed, thereby suppressing the desorption of europium from the sialon powder (a).

[0028] The present inventors also believe that by including step (B), europium in the sialon powder (a) can be reduced more effectively, thereby improving the luminescence intensity of the resulting sialon phosphor powder. Furthermore, the inventors believe that by including step (B), the distortion of the crystal lattice in the resulting SiAlON phosphor powder is optimized, and defects and impurities are removed, thereby improving the luminescence intensity of the SiAlON phosphor powder.

[0029] The europium halide includes, for example, at least one selected from the group consisting of europium fluoride, europium chloride, europium bromide, and europium iodide, and preferably includes europium fluoride.

[0030] In the europium compound, the valence of europium may be divalent or trivalent, but preferably includes trivalent.

[0031] The europium compound preferably includes at least one selected from the group consisting of europium oxide and europium halide, more preferably includes at least one selected from the group consisting of europium oxide and europium fluoride, and even more preferably includes at least one selected from the group consisting of europium (III) oxide (i.e., Eu2O3) and europium (III) fluoride (i.e., EuF3).

[0032] The melting point of the europium compound is not particularly limited, but may be, for example, 800°C or higher and 2500°C or lower, 900°C or higher and 2100°C or lower, or 1000°C or higher and 1500°C or lower.

[0033] In step (B), the amount of the europium compound is, when the total of the sialon powder (a) in which europium is dissolved and the europium compound is taken as 100 mass%, preferably 0.05 mass% or more, more preferably 0.06 mass% or more, even more preferably 0.07 mass% or more, even more preferably 0.08 mass% or more, and even more preferably 0.09 mass% or more, from the viewpoint of further improving the luminous intensity of the sialon phosphor powder; and preferably 2.00 mass% or less, more preferably 1.80 mass% or less, even more preferably 1.50 mass% or less, even more preferably 1.30 mass% or less, and even more preferably 1.10 mass% or less, from the viewpoint of further improving the performance balance between the luminous intensity and diffuse reflectance of the sialon phosphor powder.

[0034] The europium compound may be used alone or in combination with two or more europium compounds, but from the viewpoint of preventing the reaction system from becoming complicated, it is preferable to use only one europium compound.

[0035] In step (B), the annealing temperature is 1000°C or higher and lower than 1300°C. The annealing temperature is preferably 1050°C or higher, more preferably 1100°C or higher, even more preferably 1130°C or higher, even more preferably 1150°C or higher, even more preferably 1200°C or higher, and even more preferably 1250°C or higher, from the viewpoint of further improving the annealing effect and further improving the luminescence intensity of the sialon phosphor powder, and is preferably 1290°C or lower, from the viewpoint of further suppressing the decomposition of the crystal lattice of the sialon phosphor powder and further improving the luminescence intensity of the sialon phosphor powder.

[0036] In step (B), the annealing time is preferably 6 hours or more, more preferably 7 hours or more, and even more preferably 8 hours or more, from the viewpoint of further improving the annealing effect and further improving the luminescence intensity of the sialon phosphor powder, and is preferably 30 hours or less, more preferably 27 hours or less, and even more preferably 25 hours or less, from the viewpoint of further suppressing the decomposition of the crystal lattice of the sialon phosphor powder and further improving the luminescence intensity of the sialon phosphor powder.

[0037] In step (B), the annealing temperature is more preferably 1100° C. or higher and lower than 1300° C., and the annealing time is more preferably 8 hours or higher and 30 hours or lower. By setting the annealing temperature and annealing time within the above ranges, the annealing effect can be further improved while the decomposition of the crystal lattice of the SiAlON phosphor powder can be further suppressed, thereby further improving the luminescence intensity of the SiAlON phosphor powder.

[0038] In step (B), the atmosphere in which the annealing treatment is performed is not particularly limited, but the annealing treatment is preferably performed in an atmosphere containing at least one gas selected from the group consisting of a rare gas, a reducing gas, and an inert gas. In step (B), the annealing treatment may be carried out in a mixed gas atmosphere of two or more gases selected from the group consisting of rare gases, reducing gases, and inert gases.

[0039] The rare gas includes, for example, at least one selected from the group consisting of argon and helium, and preferably includes argon. The reducing gas includes, for example, at least one selected from the group consisting of ammonia, hydrocarbon, carbon monoxide, and hydrogen, and preferably includes hydrogen. The inert gas includes, for example, nitrogen.

[0040] Among these, in step (B), the annealing treatment is preferably carried out in an argon gas atmosphere.

[0041] <Process (C)> The method for producing a sialon phosphor powder of this embodiment preferably further comprises, after the step (B), a step (C) of treating the sialon powder (b) with an acid. By carrying out step (C), impurities and heterogeneous phases (phases that do not contribute to light emission or have low light emission efficiency) on the surface of the sialon powder (b) can be reduced, and the light emission intensity of the sialon phosphor powder can be further improved.

[0042] Step (C) can be carried out, for example, by adding the sialon powder (b) to an acid aqueous solution and stirring it. After stirring, the precipitated sialon powder (b) is preferably separated by filtration, and any substances adhering to the sialon powder (b) are preferably washed with water.

[0043] In step (C), the aqueous acid solution contains at least one selected from the group consisting of, for example, hydrofluoric acid, sulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, etc. Among these, it is preferable to use a mixed acid of hydrofluoric acid and nitric acid as the aqueous acid solution, from the viewpoint of further improving the efficiency of removing impurities and heterogeneous phases.

[0044] In step (C), the acid treatment time, acid treatment temperature, etc. are not particularly limited, but for example, the acid treatment time may be 10 minutes or more and 6 hours or less, and the acid treatment temperature may be 25°C or more and 90°C or less.

[0045] <Other processes> The method for producing a sialon phosphor powder according to this embodiment may include other steps in addition to the steps described above. Examples of the other steps include a crushing / disintegration step, a refining step, a drying step, a sieving / classification step, etc. The order in which the other steps are performed is not particularly limited, and for example, the other steps may be performed between step (A) and step (B).

[0046] [Sialon phosphor powder] Hereinafter, preferred embodiments of the sialon phosphor powder obtained by the method for producing a sialon phosphor powder according to this embodiment will be described.

[0047] The sialon phosphor powder of this embodiment may contain either a β-sialon phosphor powder or an α-sialon phosphor powder, but preferably contains a β-sialon phosphor powder.

[0048] The sialon phosphor powder of this embodiment is represented by the general formula Si 6-z Al z O z N 8-z In the general formula, z is 0.0 <z≦4.2であってよく、0.0<z≦1.0であってもよい。 In the general formula, by making z a smaller value, the emission peak wavelength of the sialon phosphor powder can be made shorter.

[0049] The crystal structure, composition, etc. of the sialon phosphor powder of this embodiment can be adjusted to a desired range by, for example, appropriately adjusting the mixing ratio of the raw material powder mixture in step (A-1), the firing conditions, etc.

[0050] The luminescence intensity of the sialon phosphor powder of this embodiment is preferably 215% or more, and more preferably 218% or more, when the peak intensity of the YAG:Ce phosphor is 100%, and the upper limit is not particularly limited, but may be, for example, 260% or less, 250% or less, or 240% or less. Here, the YAG:Ce phosphor refers to P46Y3 manufactured by Mitsubishi Chemical Corporation.

[0051] The emission peak wavelength of the sialon phosphor powder of this embodiment is preferably 527.0 nm or more and 551.0 nm or less, more preferably 530.0 nm or more and 540.0 nm or less, and even more preferably 535.0 nm or more and 538.0 nm or less.

[0052] The external quantum efficiency of light with a wavelength of 455 nm of the SiAlON phosphor powder of this embodiment is preferably 35.0% or more, more preferably 40.0% or more, and even more preferably 44.0% or more, and the upper limit is not particularly limited, but may be 75.0% or less, 60.0% or less, or 55.0% or less.

[0053] The values ​​of the luminous intensity, luminous peak intensity, and external quantum efficiency of light with a wavelength of 455 nm of the sialon phosphor powder of this embodiment are the values ​​measured by the methods described in the examples.

[0054] The use of the sialon phosphor powder of this embodiment is not particularly limited, but it can be used, for example, in light emitting devices such as LEDs, lighting devices, and the like.

[0055] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted. Furthermore, the present invention is not limited to the above-described embodiment, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0056] The present embodiment will be described in detail below based on examples and comparative examples, but the present embodiment is not limited to the descriptions of these examples.

[0057] [Example 1] <Process (A)> The raw materials were weighed into a container so that the silicon nitride (Si3N4) was 96.0% by mass, aluminum nitride (AlN) was 2.8% by mass, aluminum oxide (Al2O3) was 0.5% by mass, and europium oxide (Eu2O3) was 0.7% by mass, and mixed using a V-type mixer (Tsutsui Scientific Instruments Co., Ltd.) to obtain a mixture. The obtained mixture was passed through a sieve with 250 μm openings to remove aggregates, thereby obtaining a raw material composition. The aggregates that did not pass through the sieve were crushed and the particle size was adjusted so that they would pass through the sieve.

[0058] 200 g of the raw material composition prepared as described above was weighed into a cylindrical boron nitride container with a lid (manufactured by Denka Corporation, a molded product mainly composed of boron nitride (product name: Denka Boron Nitride N-1), inner diameter: 10 cm, height: 10 cm). The container was then placed in an electric furnace equipped with a carbon heater, and heated to 2020°C under a nitrogen gas atmosphere (pressure: 0.90 MPaG). Heating was continued at this temperature for 8 hours (step (A-1)). After heating, the sample, which had become loosely aggregated lumps in the container, was placed in a mortar and crushed. After crushing, the sample was passed through a sieve with 250 μm openings to obtain a powdered sintered body. The resulting sintered body corresponds to the europium-doped sialon powder (a) of this embodiment.

[0059] <Process (B)> Next, europium oxide (Eu2O3, manufactured by Kojundo Chemical Laboratory Co., Ltd., melting point: 2050°C) was added to the sintered body to prepare a mixture. The amount of europium oxide was 1.0% by mass, assuming the total of the sintered body and europium oxide to be 100% by mass. The resulting mixture was filled into a cylindrical boron nitride container, which was then placed in an electric furnace equipped with a carbon heater. The temperature was raised to 1285°C in an argon gas atmosphere (pressure: 0.025 MPaG), and heating was continued at this temperature for 8 hours. After heating, the loosely agglomerated particles remaining in the container were crushed in a mortar and passed through a sieve with 250 μm openings to obtain a powder.

[0060] <Process (C)> Next, the powder obtained in step (B) was added to a mixed acid of hydrofluoric acid (concentration: 50% by mass) and nitric acid (concentration: 70% by mass) (a 1:1 volume ratio of hydrofluoric acid and nitric acid), and acid treatment was performed for 30 minutes while stirring at 75°C. After the acid treatment, the stirring was stopped, the powder was allowed to settle, and the supernatant and fine powder refined by the acid treatment were removed. Distilled water was then added and the mixture was stirred again. The stirring was stopped, the powder was allowed to settle, and the supernatant and fine powder were removed. This procedure was repeated until the pH of the aqueous solution was 8 or less and the supernatant was transparent. The resulting precipitate was filtered, dried, and passed through a sieve with 250 μm openings, yielding a SiAlON phosphor powder of Example 1. Powder X-ray diffraction measurement of the SiAlON phosphor powder of Example 1 revealed that the crystalline phase present was a single β-SiAlON phase, indicating that a β-SiAlON phosphor powder was obtained.

[0061] [Examples 3 and 5] Sialon phosphor powders of Examples 3 and 5 were obtained in the same manner as in Example 1, except that in step (B) of Example 1, the heating temperature and heating time were set to the conditions shown in Table 1. Powder X-ray diffraction measurements were performed on the sialon phosphor powders of Examples 3 and 5, and it was found that the crystalline phase present in both cases was a single β-sialon phase, and that β-sialon phosphor powders were obtained in both cases.

[0062] [Examples 2, 4, and 6] In step (B) of Example 1, europium fluoride (EuF3, manufactured by Kojundo Chemical Laboratory Co., Ltd., melting point: 1276°C) was added instead of europium oxide to prepare a mixture, and the heating temperature and heating time were set as shown in Table 1. The sialon phosphor powders of Examples 2, 4, and 6 were obtained in the same manner as in Example 1, except that the amount of europium fluoride was 1.0% by mass when the total of the fired body and europium fluoride was taken as 100% by mass. Powder X-ray diffraction measurements were performed on the sialon phosphor powders of Examples 2, 4, and 6, and it was found that the crystalline phase present in all cases was a single β-sialon phase, and that β-sialon phosphor powders were obtained in all cases.

[0063] [Comparative Examples 1 to 2] Sialon phosphor powders of Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that in step (B) of Example 1, europium oxide was not added and the heating temperature and heating time were set to the conditions shown in Table 1. In other words, in Comparative Examples 1 and 2, only the fired body was annealed in step (B). Powder X-ray diffraction measurements were performed on the sialon phosphor powders of Comparative Examples 1 and 2, and it was found that the crystalline phase present in both cases was a single β-sialon phase, and that β-sialon phosphor powders had been obtained in both cases.

[0064] [evaluation] The SiAlON phosphor powders of each Example and Comparative Example were evaluated as follows.

[0065] <Emission intensity, emission peak wavelength> The peak intensity of the sialon phosphor powder was measured using a spectrofluorometer (Hitachi High-Technologies Corporation, product name: F-7000) calibrated by the rhodamine B method and a standard light source as follows.

[0066] First, the phosphor powder was packed into a dedicated solid sample holder. Next, the fluorescent spectrum was measured by irradiating the phosphor powder with excitation light split into 455 nm wavelengths using a spectrofluorometer, and the peak intensity and emission peak wavelength were determined from the obtained fluorescent spectrum. The peak intensity varies depending on the measurement device and conditions, so the units are arbitrary. The measurement conditions were the same for each example and comparative example, and measurements for each example and comparative example were performed consecutively. The emission intensities listed in Table 1 are intensities when the peak intensity of a YAG:Ce phosphor (manufactured by Mitsubishi Chemical Corporation, product name: P46Y3) is taken as 100%.

[0067] <External quantum efficiency of light with a wavelength of 455 nm> The phosphor powder was filled into a concave cell so that the surface was smooth, and the cell was attached to the opening of an integrating sphere. Monochromatic light with a wavelength of 455 nm, split from a light source (Xe lamp), was introduced into the integrating sphere using an optical fiber as excitation light for the phosphor. This monochromatic light was irradiated onto the phosphor powder, and the fluorescence spectrum was measured. A spectrophotometer (Otsuka Electronics Co., Ltd., product name: MCPD-7000) was used for the measurement.

[0068] The number of reflected excitation light photons (Qref) and the number of fluorescent photons (Qem) were calculated from the obtained fluorescence spectrum 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. Using the same device, a standard reflector with a reflectance of 99% (Spectralon (registered trademark), manufactured by Labsphere) was attached to the opening of the integrating sphere to measure the spectrum of excitation light with a wavelength of 455 nm. The number of excitation light photons (Qex) was calculated from the spectrum in the wavelength range of 450 to 465 nm.

[0069] From the above calculation results, the external quantum efficiency of the phosphor powder at a wavelength of 455 nm was calculated based on the following calculation formula. External quantum efficiency = (Qem / Qex) x 100

[0070] The evaluation results of each example and comparative example are shown in Table 1. Table 1 also shows the evaluation results of a YAG:Ce phosphor (manufactured by Mitsubishi Chemical Corporation, product name: P46Y3) as Reference Example 1. The above-mentioned measured values ​​may fluctuate if the manufacturer of the measuring device, production lot number, etc., changes. Therefore, if the manufacturer, production lot number, etc., of the measuring device is changed, each measured value can be corrected using the measured value from the standard sample as the reference value.

[0071] [Table 1]

[0072] As shown in Table 1, the sialon phosphor powder of the example had improved luminous intensity compared to the sialon phosphor powder of the comparative example. That is, it can be seen that the method for producing a sialon phosphor powder of this embodiment makes it possible to obtain a sialon phosphor powder with improved luminous intensity.

Claims

1. A step (A) of preparing a sialon powder (a) in which europium is solid-dissolved; and (B) a step of annealing a mixture containing a europium compound and the sialon powder (a) in which europium is dissolved to obtain the sialon powder (b), the europium compound includes at least one selected from the group consisting of europium oxide, europium halide, europium hydroxide, europium nitride, and europium oxynitride, In the step (B), the annealing temperature is 1000°C or higher and lower than 1300°C.

2. 2. The method for producing a sialon phosphor powder according to claim 1, wherein the annealing time in the step (B) is 6 hours or more and 30 hours or less.

3. 3. The method for producing a sialon phosphor powder according to claim 1, wherein in the step (B), the annealing treatment is performed in an atmosphere containing at least one gas selected from the group consisting of a rare gas, a reducing gas, and an inert gas.

4. 3. The method for producing a sialon phosphor powder according to claim 1, wherein the europium compound includes at least one selected from the group consisting of europium oxide and europium halide.

5. 3. The method for producing a sialon phosphor powder according to claim 1 or 2, wherein in the step (B), the amount of the europium compound is 0.05 mass% or more and 2.00 mass% or less, when the total of the sialon powder (a) in which europium is solid-dissolved and the europium compound is 100 mass%.

6. 3. The method for producing a sialon phosphor powder according to claim 1 or 2, wherein the step (A) comprises a step (A-1) of firing a raw material powder mixture containing a raw material powder containing silicon, a raw material powder containing aluminum, and a raw material powder containing europium.

7. 7. The method for producing a sialon phosphor powder according to claim 6, wherein in the step (A-1), the firing temperature is 1700° C. or higher and 2500° C. or lower.

8. 3. The method for producing a sialon phosphor powder according to claim 1, further comprising a step (C) of treating the sialon powder (b) with an acid after the step (B).

9. The method for producing a sialon phosphor powder according to claim 1 or 2, wherein the sialon phosphor powder includes a β-sialon phosphor powder.

10. 3. The method for producing a sialon phosphor powder according to claim 1, wherein the sialon phosphor powder has an emission peak wavelength of 527.0 nm or more and 551.0 nm or less.

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