Method for producing sialon phosphor powder

Abstract

To provide a method for producing sialon phosphor powder, whereby it is possible to create sialon phosphor powder with enhanced emission intensity.SOLUTION: A method for producing sialon phosphor powder includes step (A) for preparing a sialon powder (a) comprising europium dissolved therein, and step (B) for annealing a mixture that comprises a europium halide compound and the sialon powder (a) comprising europium dissolved therein, to create a sialon powder (b).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. It is stated that the method for producing a β-sialon phosphor described in Patent Document 1 can provide a method for producing a β-sialon phosphor with excellent luminance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-2278 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides a method for producing a sialon phosphor powder, which is capable of obtaining a sialon phosphor powder having improved luminous intensity. [Means for solving the problem]

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

[0007] [1] A step (A) of preparing a sialon powder (a) having europium dissolved therein; and (B) annealing a mixture containing a europium halide compound and the sialon powder (a) in which the europium is dissolved to obtain the sialon powder (b). [2] The method for producing a sialon phosphor powder according to [1] above, wherein the melting point of the europium halide compound is lower than the annealing temperature in the step (B). [3] The method for producing a sialon phosphor powder according to [1] or [2], wherein in the step (B), the amount of the europium halide 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 halide compound is 100 mass%. [4] The method for producing a sialon phosphor powder according to any one of the above [1] to [3], wherein the europium halide compound contains europium fluoride. [5] The method for producing a sialon phosphor powder according to any one of the above [1] to [4], wherein the melting point of the europium halide compound is 800° C. or higher and 1500° C. or lower. [6] The method for producing a sialon phosphor powder according to any one of the above [1] to [5], wherein in the step (B), the annealing temperature is 1000° C. or higher and 1700° C. or lower. [7] The method for producing a sialon phosphor powder according to any one of the above [1] to [6], 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. [8] The method for producing a sialon phosphor powder according to any one of [1] to [7] above, wherein in the step (B), the annealing treatment is carried out for a period of time of 1 hour or more and 30 hours or less. [9] The method for producing a Sialon phosphor powder according to any one of the above [1] to [8], 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.

[10] The method for producing a sialon phosphor powder according to the above [9], wherein in the step (A-1), the firing temperature is 1800° C. or higher and 2500° C. or lower.

[11] The method for producing a sialon phosphor powder according to any one of the above [1] to

[10] , further comprising a step (C) of treating the sialon powder (b) with an acid after the step (B).

[12] The method for producing a sialon phosphor powder according to any one of the above [1] to

[11] , wherein the sialon phosphor powder contains a β-sialon phosphor powder. Effect of the Invention

[0008] According to the present invention, there can be provided a method for producing a sialon phosphor powder, which is capable of obtaining a sialon phosphor powder with improved luminous intensity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described. Unless otherwise specified, a numerical range "A to B" indicates A or more and B or less.

[0010] [Manufacturing method of SiAlON phosphor powder] The method for producing a sialon phosphor powder of this embodiment includes a step (A) of preparing a sialon powder (a) having europium dissolved therein, and a step (B) of obtaining a sialon powder (b) by annealing a mixture containing a europium halide compound and the sialon powder (a) having europium dissolved therein. Hereinafter, in this specification, "sialon powder (a) having europium dissolved therein" may be abbreviated to "sialon powder (a)".

[0011] Hereinafter, each step of the method for producing a SiAlON phosphor powder according to this embodiment will be specifically described.

[0012] <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.

[0013] In the step (A), the method for preparing the sialon powder (a) in which europium is dissolved as a solid solution is not particularly limited, and for example, the sialon powder (a) may be prepared by a known method.

[0014] The 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.

[0015] The silicon-containing raw material powder contains, for example, at least one selected from the group consisting of silicon nitride and silicon dioxide, and among these, silicon nitride is preferred.

[0016] 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 among these, preferably includes at least one selected from the group consisting of aluminum nitride and aluminum oxide.

[0017] 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 among these, preferably contains 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.

[0018] 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 for example, the raw materials may be mixed using a V-type mixer.

[0019] In the raw material powder mixture, the mixing ratio of each raw material may be appropriately adjusted based on the composition of the target SiAlON phosphor powder.

[0020] From the viewpoint of further improving the luminescence intensity of the SiAlON phosphor powder, the firing temperature in step (A-1) is preferably 1800°C or higher, more preferably 1850°C or higher, even more preferably 1900°C or higher, even more preferably 1920°C or higher, and 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.

[0021] The firing time in step (A-1) is not particularly limited, and may be, for example, from 1 hour to 30 hours, or from 3 hours to 25 hours.

[0022] In the step (A-1), the raw material powder mixture may be fired, for example, in a nitrogen atmosphere.

[0023] The method may further include a second firing step of firing the fired body obtained in step (A-1) after step (A-1). In addition, after the second firing step, the firing step may be further performed multiple times. The firing conditions in the second and subsequent firing steps are not particularly limited, but the preferred ranges are the same as those in step (A-1). When the second or subsequent firing step is performed, 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.

[0024] The sintered body obtained in step (A-1) can be the sialon powder (a) having europium dissolved therein according to this embodiment. When 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) having europium dissolved therein according to this embodiment. The fired product may be subjected to crushing, sieving, classification, and other processes.

[0025] <Process (B)> The method for producing a sialon phosphor powder of this embodiment includes a step (B) of annealing a mixture containing a europium halide compound and a sialon powder (a) in which europium is dissolved, to obtain a sialon powder (b).

[0026] The method for producing a Sialon phosphor powder according to the present embodiment includes step (B), and thereby the luminescence intensity of the obtained Sialon phosphor powder is improved. Although the reason for this is not clear, the present inventors presume it as follows. The present inventors believe that in the conventional manufacturing method of sialon phosphor powder, europium in the sialon powder (a) may be desorbed during the annealing process, resulting in a decrease in the luminescence intensity of the sialon phosphor powder. Therefore, the inventors believe that by annealing the sialon powder (a) in the presence of a europium halide compound, the desorption of europium in the sialon powder (a) can be suppressed, and the luminescence intensity of the resulting sialon phosphor powder can be improved. More specifically, the present inventors believe that by annealing the sialon powder (a) in the presence of a europium halide compound, even if europium in the sialon powder (a) is desorbed, it is possible to supply europium derived from the europium halide compound, and as a result, the desorption of europium in the sialon powder (a) can be suppressed.

[0027] The europium halide compound 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.

[0028] In the europium halide compound, the valency of europium may be divalent or trivalent, but preferably includes trivalent.

[0029] The europium halide compound specifically includes at least one selected from the group consisting of EuF3, EuF2, EuCl3, EuCl2, EuBr3, EuBr2, and EuI2, and preferably includes EuF3.

[0030] The melting point of the europium halide compound is not particularly limited, but is preferably 800°C or higher, more preferably 900°C or higher, even more preferably 1000°C or higher, even more preferably 1100°C or higher, even more preferably 1200°C or higher, and is preferably 1500°C or lower, more preferably 1450°C or lower, even more preferably 1400°C or lower, even more preferably 1350°C or lower.

[0031] The melting point of the europium halide compound is preferably lower than the annealing temperature in step (B). If the melting point of the europium halide compound is lower than the annealing temperature, the europium halide compound is liquid during the annealing, and is therefore likely to be present around the sialon powder (a).As a result, the inventors believe that the elimination of europium from the sialon powder (a) can be further suppressed, and the luminescence intensity of the resulting sialon phosphor powder is further improved.

[0032] In step (B), the amount of the europium halide compound, when the total of the sialon powder (a) in which europium is dissolved and the europium halide compound is taken as 100 mass%, is 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 emission intensity of the sialon phosphor powder, and is 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 of the emission intensity and diffuse reflectance of the sialon phosphor powder.

[0033] The europium halide compound may be used alone or in combination with two or more kinds of europium halide compounds. From the viewpoint of preventing the reaction system from becoming complicated, it is preferable to use only one kind of europium halide compound.

[0034] In step (B), the annealing temperature is preferably 1000°C or higher, more preferably 1100°C or higher, even more preferably 1200°C or higher, and preferably 1700°C or lower, more preferably 1600°C or lower, even more preferably 1500°C or lower.

[0035] The annealing temperature is preferably higher than the melting point of the europium halide compound, and is preferably lower than the firing temperature in step (A-1).

[0036] In step (B), the atmosphere in which the annealing treatment is performed is not particularly limited, but it is preferable to perform the annealing treatment 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 the step (B), the annealing treatment may be performed in a mixed gas atmosphere of two or more kinds selected from the group consisting of a rare gas, a reducing gas, and an inert gas.

[0037] The rare gas includes, for example, at least one selected from the group consisting of argon, helium, and the like, 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.

[0038] Among these, it is preferable to carry out the annealing treatment in step (B) under an argon gas atmosphere.

[0039] In step (B), the annealing time is not particularly limited, but is preferably 1 hour or more, more preferably 3 hours or more, even more preferably 6 hours or more, even more preferably 8 hours or more, and is preferably 30 hours or less, more preferably 27 hours or less, even more preferably 25 hours or less.

[0040] <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, which is preferable because it allows the light emission intensity of the Sialon phosphor powder to be further improved.

[0041] Step (C) can be carried out, for example, by putting the sialon powder (b) into an acid aqueous solution and stirring it. It is preferable to separate the precipitated sialon powder (b) after stirring by filtration and to wash away any substances adhering to the sialon powder (b) with water.

[0042] 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, and 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.

[0043] In step (C), the acid treatment time, the acid treatment temperature, etc. are not particularly limited. 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.

[0044] <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 purification step, a drying step, a sieving / classification step, etc. The order in which the other steps are performed is not particularly limited, and the other steps may be performed, for example, between step (A) and step (B).

[0045] [Sialon phosphor powder] Hereinafter, preferred embodiments of the sialon phosphor powder obtained by the method for producing a sialon phosphor powder according to the present embodiment will be described.

[0046] The sialon phosphor powder of this embodiment may contain β-sialon phosphor powder or α-sialon phosphor powder, but preferably contains β-sialon phosphor powder.

[0047] The sialon phosphor powder of the present 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。

[0048] The crystal structure, composition, and the like of the Sialon phosphor powder of this embodiment can be adjusted to be within a desired range, for example, by appropriately adjusting the mixing ratio of the raw material powder mixture in step (A-1), the firing conditions, and the like.

[0049] The luminescence intensity of the Sialon phosphor powder of this embodiment is preferably 114.6% or more, more preferably 114.8% or more, and even more preferably 115.0% or more, when the luminescence intensity of a standard sample of β-type Sialon phosphor is taken as 100.0%, and the upper limit is not particularly limited, but may be, for example, 140.0% or less, 130.0% or less, 125.0% or less, or 123.0% or less. Here, the standard sample of β-SiAlON phosphor refers to NIMS Standard Green (manufactured by SiAlON Co., Ltd.).

[0050] The absorptance of the sialon phosphor powder of this embodiment for light with a wavelength of 455 nm may be, for example, 79.0% or more, 80.0% or more, and 90.0% or less, 86.0% or less, 84.0% or less, or 83.0% or less.

[0051] The internal quantum efficiency of the sialon phosphor powder of this embodiment is preferably 80.8% or more, more preferably 81.0% or more, and even more preferably 81.3% or more, and the upper limit is not particularly limited, but may be, for example, 90.0% or less, 87.0% or less, 85.0% or less, or 84.0% or less.

[0052] The external quantum efficiency of the sialon phosphor powder of this embodiment is preferably 65.2% or more, more preferably 65.4% or more, and the upper limit is not particularly limited, but may be 80.0% or less, 75.0% or less, 70.0% or less, 68.5% or less, or 68.0% or less.

[0053] The diffuse reflectance of the SiAlON phosphor powder of this embodiment at a wavelength of 800 nm may be, for example, 96.0% or more, or 96.5% or more, and may be 100.0% or less, 99.0% or less, or 98.5% or less.

[0054] The diffuse reflectance of the SiAlON phosphor powder of this embodiment at a wavelength of 700 nm may be, for example, 96.0% or more, or 96.5% or more, and may be 100.0% or less, 99.0% or less, or 98.5% or less.

[0055] The diffuse reflectance of the SiAlON phosphor powder of this embodiment at a wavelength of 600 nm may be, for example, 95.5% or more, or 96.0% or more, and may be 100.0% or less, 99.0% or less, or 98.5% or less.

[0056] The diffuse reflectance of the SiAlON phosphor powder of this embodiment at a wavelength of 500 nm may be, for example, 79.5% or more, 80.0% or more, and 90.0% or less, 85.0% or less, 82.5% or less, or 82.0% or less.

[0057] The values ​​of the emission intensity, the absorptance of light with a wavelength of 455 nm, the internal quantum efficiency, the external quantum efficiency, and the diffuse reflectance of the SiAlON phosphor powder of this embodiment are the values ​​measured by the methods described in the Examples.

[0058] The applications of the sialon phosphor powder of this embodiment are not particularly limited, but it can be used, for example, in light emitting devices such as LEDs, lighting devices, and the like.

[0059] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can also be adopted. Furthermore, the present invention is not limited to the above-described embodiment, and modifications and improvements within the scope of the present invention that can achieve the object of the present invention are included in the present invention. EXAMPLES

[0060] The present embodiment will be described in detail below based on examples and comparative examples. Note that the present embodiment is not limited to the descriptions of these examples.

[0061] [Example 1] <Process (A)> Each raw material was weighed out and mixed in a container so that silicon nitride (Si3N4) was 96.0 mass%, aluminum nitride (AlN) was 2.8 mass%, aluminum oxide (Al2O3) was 0.5 mass%, and europium oxide (Eu2O3) was 0.7 mass%, and the mixture was obtained by a V-type mixer (Tsutsui Rikagaku Kikai Co., Ltd.). The mixture obtained was passed through a sieve with a mesh size of 250 μm 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.

[0062] 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 Co., Ltd., a molded product mainly composed of boron nitride (product name: Denka Boron Nitride N-1), inner diameter: 10 cm, height: 10 cm). Then, this container was placed in an electric furnace equipped with a carbon heater, and the temperature was raised to 2020°C under a nitrogen gas atmosphere (pressure: 0.90 MPaG), and heating was performed at a heating temperature of 2020°C for 8 hours (step (A-1)). After heating, the sample that had become loosely aggregated lumps in the container was taken in a mortar and crushed. After crushing, the sample was passed through a sieve with an opening of 250 μm to obtain a powdered sintered body. The obtained sintered body corresponds to the sialon powder (a) in which europium is dissolved in solid solution according to this embodiment.

[0063] <Process (B)> Next, europium fluoride (EuF3, manufactured by Kojundo Chemical Laboratory Co., Ltd., melting point: 1276°C) was mixed with the sintered body to prepare a mixture. The amount of europium fluoride was adjusted to 0.10% by mass when the total of the sintered body and europium fluoride was 100% by mass. The obtained mixture was filled into a cylindrical boron nitride container, and the container was placed in an electric furnace equipped with a carbon heater. The temperature was raised to 1450°C under an argon gas atmosphere (pressure: 0.025 MPaG), and heating was performed at the heating temperature of 1450°C for 8 hours. After heating, the lumps in which the particles were loosely aggregated in the container were crushed in a mortar and passed through a 250 μm sieve to obtain a powder.

[0064] <Process (C)> Next, the powder obtained in step (B) was added to a mixed acid (hydrofluoric acid and nitric acid mixed in a volume ratio of 1:1) of hydrofluoric acid (concentration: 50% by mass) and nitric acid (concentration: 70% by mass), and acid treatment was performed for 30 minutes while stirring at a temperature of 75°C. After the acid treatment, the stirring was stopped, the powder was precipitated, and the supernatant and fine powder refined by the acid treatment were removed. Then, distilled water was further added and the mixture was stirred again. The stirring was stopped, the powder was precipitated, and the supernatant and fine powder were removed. This operation was repeated until the pH of the aqueous solution was 8 or less and the supernatant was transparent, and the obtained precipitate was filtered, dried, and passed through a sieve with an opening of 250 μm to obtain a sialon phosphor powder of Example 1.

[0065] [Examples 2 to 9] The sialon phosphor powders of Examples 2 to 9 were obtained in the same manner as in Example 1, except that in step (B) of Example 1, the amount of europium fluoride added, the heating temperature, and the heating time were set to the conditions shown in Table 1.

[0066] [Comparative Example 1] A sialon phosphor powder of Comparative Example 1 was obtained in the same manner as in Example 1, except that europium fluoride was not added in step (B) of Example 1. That is, Comparative Example 1 is a level in which only the fired body was annealed in step (B).

[0067] [Comparative Example 2] A sialon phosphor powder of Comparative Example 2 was obtained in the same manner as in Example 1, except that in step (B) of Example 1, europium oxide (Eu2O3, manufactured by Kojundo Chemical Laboratory Co., Ltd., melting point: 2050°C) was blended instead of europium fluoride to prepare a mixture. The amount of europium oxide was adjusted to 1.00 mass% when the total of the fired body and europium oxide was 100 mass%.

[0068] [evaluation] The SiAlON phosphor powders of each of the Examples and Comparative Examples were evaluated as follows. The evaluation results are shown in Table 1.

[0069] <Emission intensity> The peak intensity of the SiAlON phosphor powder was measured as follows using a spectrofluorometer (Hitachi High-Technologies Corporation, product name: F-7000) calibrated by the Rhodamine B method and a standard light source.

[0070] 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 to a wavelength of 455 nm using a spectrofluorometer, and the peak intensity was calculated from the obtained fluorescent spectrum. The peak intensity varies depending on the measuring device and conditions, so the unit is arbitrary. The measuring conditions are the same in each example and comparative example, and the measurements in each example and comparative example were performed continuously. The emission intensity shown in Table 1 indicates the intensity when the peak intensity in Reference Example 1 described later is taken as 100.0%.

[0071] <Absorptance of light at 455 nm wavelength, internal quantum efficiency, external quantum efficiency> 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 was split from a light source (Xe lamp) and introduced into the integrating sphere using an optical fiber as excitation light for the phosphor. The phosphor powder was irradiated with this monochromatic light, and the fluorescence spectrum was measured. A spectrophotometer (Otsuka Electronics Co., Ltd., product name: MCPD-7000) was used for the measurement.

[0072] From the obtained fluorescence spectrum data, the number of excitation reflected light photons (Qref) and the number of fluorescence photons (Qem) were calculated. The number of excitation reflected light photons was calculated in the same wavelength range as the number of excitation light photons, and the number of fluorescence photons was calculated in the wavelength range of 465 to 800 nm. In addition, 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. At this time, the number of excitation light photons (Qex) was calculated from the spectrum in the wavelength range of 450 to 465 nm.

[0073] From the above calculation results, the absorptance of light with a wavelength of 455 nm, the internal quantum efficiency, and the external quantum efficiency of the phosphor powder were calculated based on the following formulas. Absorption rate of light with a wavelength of 455 nm = ((Qex-Qref) / Qex) x 100 Internal quantum efficiency = (Qem / (Qex-Qref)) x 100 External quantum efficiency = (Qem / Qex) x 100

[0074] <Diffuse reflectance> The diffuse reflectance of the phosphor powder was measured using an integrating sphere device (manufactured by JASCO Corporation, product name: ISV-469) attached to an ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, product name: V-550). Specifically, baseline correction was performed using a standard reflector (Spectralon (registered trademark)), and a solid sample holder filled with the phosphor powder was attached to a predetermined position of the device to measure the diffuse reflectance in the wavelength range from 500 nm to 850 nm. The diffuse reflectances at 800 nm, 700 nm, 600 nm, and 500 nm were then calculated.

[0075] The evaluation results of each of the examples and comparative examples are shown in Table 1.

[0076] Table 1 also shows, as Reference Example 1, the evaluation results of a standard sample of a β-sialon phosphor (manufactured by Sialon Corporation, NIMS Standard Green lot No. NSG1301). The above-mentioned measured values ​​may vary if the manufacturer of the measuring device, the manufacturing lot number, etc. are changed. Therefore, when the manufacturer, manufacturing lot number, etc. of the measuring device are changed, each measured value can be corrected using the measured value of the standard sample as the reference value.

[0077] [Table 1]

[0078] As shown in Table 1, the phosphor powder of the example had improved luminous intensity compared to the phosphor powder of the comparative example. That is, it can be seen that the method for producing a sialon phosphor powder of the present embodiment makes it possible to obtain a sialon phosphor powder with improved luminous intensity.

[0079] Furthermore, the phosphor powder of the Example also had improved internal quantum efficiency and external quantum efficiency compared to the phosphor powder of the Comparative Example. That is, it can be understood that the method for producing a Sialon phosphor powder of the present embodiment makes it possible to obtain a Sialon phosphor powder with improved internal quantum efficiency and external quantum efficiency.

Claims

1. A step (A) of preparing a sialon powder (a) having europium dissolved therein; and (B) a step of annealing a mixture containing a europium halide compound and the sialon powder (a) in which the europium is dissolved to obtain a sialon powder (b).

2. 2. The method for producing a sialon phosphor powder according to claim 1, wherein the europium halide compound has a melting point lower than the annealing temperature in the step (B).

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

4. 3. The method for producing a sialon phosphor powder according to claim 1, wherein the europium halide compound includes europium fluoride.

5. 3. The method for producing a sialon phosphor powder according to claim 1, wherein the europium halide compound has a melting point of 800° C. or higher and 1500° C. or lower.

6. 3. The method for producing a sialon phosphor powder according to claim 1, wherein in the step (B), the annealing treatment temperature is 1000° C. or more and 1700° C. or less.

7. 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.

8. 3. The method for producing a sialon phosphor powder according to claim 1, wherein in the step (B), the annealing treatment is performed for a period of time ranging from 1 hour to 30 hours.

9. The method for producing a sialon phosphor powder according to claim 1 or 2, wherein the step (A) 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.

10. 10. The method for producing a sialon phosphor powder according to claim 9, wherein in the step (A-1), the firing temperature is 1800° C. or more and 2500° C. or less.

11. The method for producing a sialon phosphor powder according to claim 1 or 2, further comprising a step (C) of treating the sialon powder (b) with an acid after the step (B).

12. 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.

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