Β-type sialon phosphor, composite, wavelength conversion member, light-emitting device, and method for producing β-type sialon phosphor

Abstract

To provide a β-type sialon phosphor having excellent emission characteristics.SOLUTION: A β-type sialon phosphor contains Eu. With EuF3 taken as a reference sample, the 151Eu Moessbauer spectrum of the β-type sialon phosphor is fitted using three Lorentzian curve: (i) a first Lorentzian curve having a peak from -20 to -10 mm / s, (ii) a second Lorentzian curve having a peak from -1 to 1 mm / s, and (iii) a third Lorentzian curve having a peak located between the peak of the first Lorentzian curve and the peak of the second Lorentzian curve, and when the area bounded by the first Lorentzian curve and the baseline is A2+, the area bounded by the second Lorentzian curve and the baseline is A3+, and the area bounded by the third Lorentzian curve and the baseline is A', the ratio A3+ / A2+ is 0.15 or less and the ratio A' / A2+ is 0.36 or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a β-sialon phosphor, a composite, a wavelength conversion member, a light emitting device, and a method for manufacturing a β-sialon phosphor. More specifically, the present invention relates to a β-sialon phosphor containing Eu, a composite containing the phosphor, a wavelength conversion member including the composite, a light emitting device including the wavelength conversion member, and a method for manufacturing a β-sialon phosphor containing Eu. [Background technology]

[0002] Various studies have been conducted on β-sialon phosphors from the viewpoint of application to wavelength conversion members in light-emitting devices such as light-emitting diodes.

[0003] Patent Document 1 describes a β-sialon phosphor that uses β-sialon as a host crystal and contains Eu as a luminescent center. 2+ ,EU 3+ , and their intermediate states (Eu m When classified into three types, the proportion of these is 0.1 <Eu m / (EU 2+ +Eu 3+ +Eu m )<0.4 and Eu 2+ / (EU 2+ +Eu 3+ )>0.7. Supplementally, in Patent Document 1, the chemical state of Eu is analyzed by X-ray absorption fine structure (XAFS).

[0004] Non-Patent Document 1 mentions the improvement of the performance of β-sialon phosphors by the N2-H2 annealing direct reduction method. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-002870 [Non-patent literature]

[0006] [Non-Patent Document 1] Chem. Mater. 2018;30;494-505. Summary of the Invention [Problem to be solved by the invention]

[0007] As mentioned above, various studies have been conducted on β-sialon phosphors. However, with the need for even higher performance in lighting devices, for example, there is a demand for further improvements in the properties of β-sialon phosphors.

[0008] The present invention has been made in view of the above circumstances, and one of the objects of the present invention is to provide a β-sialon phosphor having good luminescence properties. [Means for solving the problem]

[0009] The present inventors have completed the invention provided below and solved the above problems.

[0010] 1. A β-sialon phosphor containing Eu, When EuF3 was used as a reference sample, the β-sialon phosphor 151 The Mössbauer spectrum of Eu is (i) The first Lorenz curve, whose peak is between -20 and -10 mm / s; (ii) a second Lorenz curve with a peak between -1 and 1 mm / s; (iii) a third Lorenz curve having a peak between the peak of the first Lorenz curve and the peak of the second Lorenz curve; When fitting with the three Lorentz curves, The area enclosed by the first Lorenz curve and the baseline is A 2+ year, The area enclosed by the second Lorenz curve and the baseline is A 3+ year, When the area enclosed by the third Lorenz curve and the baseline is A', A 3+ / A 2+ is less than or equal to 0.15, A' / A 2+ is 0.36 or less. 2. 1. The β-sialon phosphor according to A 3+ / A 2+ is 0.03 or more. 3. 1. The β-sialon phosphor according to 1. or 2., A' / A 2+ is 0.20 or more. 4. The β-sialon phosphor according to any one of 1. to 3., A' / A 3+ is 1.90 to 5.00. 5. The β-sialon phosphor according to any one of 1. to 4., A 2+ / (A 2+ +A 3+ +A') is 0.70 or more. 6. The β-sialon phosphor according to any one of 1. to 5., A β-sialon phosphor, wherein the peak intensity of the first Lorentz curve is 0.40 or more when the baseline of the Mössbauer spectrum is set to 0. 7. The β-sialon phosphor according to any one of 1. to 6., A β-sialon phosphor, wherein the full width at half maximum of the third Lorentz curve is 7.00 mm / s or more. 8. The β-sialon phosphor according to any one of 1. to 7., A β-sialon phosphor containing 0.10 to 2.00 mass % of Eu. 9. 10. The β-sialon phosphor according to any one of 1. to 8., Volume-based cumulative 50% diameter D measured by laser diffraction scattering method 50 A β-sialon phosphor having a particle size of 10.0 to 40.0 μm. 10. A composite comprising the β-sialon phosphor according to any one of 1. to 9. and a sealing material that seals the β-sialon phosphor. 11. 10. A wavelength conversion member comprising the composite according to claim 10. 12. 11. A light emitting device comprising: the wavelength conversion member according to claim 11; and a light source capable of emitting excitation light that excites the β-sialon phosphor in the wavelength conversion member to emit light. 13. A method for producing a β-sialon phosphor containing Eu, comprising the steps of: a firing step of firing a raw material powder obtained by mixing a europium compound, silicon nitride, and aluminum nitride to obtain a fired product; an annealing step of annealing the mixture of the fired product and SrF2 to obtain an annealed fired product; an acid treatment step of treating the annealed fired product with acid; A method for producing a β-sialon phosphor, comprising: [Effects of the Invention]

[0011] According to the present invention, a β-sialon phosphor having good luminescence properties is provided. [Brief explanation of the drawings]

[0012] [Figure 1] 1A and 1B are diagrams illustrating an example of a composite and a light-emitting device. [Figure 2] FIG. 1 is a diagram showing the Mössbauer spectrum of the β-sialon phosphor of Example 1 and the fitting of the spectrum with three Lorentz curves. [Figure 3]FIG. 1 is a diagram showing the Mössbauer spectrum of the β-sialon phosphor of Example 2 and the fitting of the spectrum with three Lorentz curves. [Figure 4] FIG. 1 is a diagram showing the Mössbauer spectrum of the β-sialon phosphor of Comparative Example 1 and the fitting of the spectrum with three Lorentz curves. [Figure 5] FIG. 10 is a diagram showing the Mössbauer spectrum of the β-sialon phosphor of Comparative Example 2 and the fitting of the spectrum with three Lorentz curves. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings, similar components are denoted by similar reference numerals and descriptions thereof will be omitted where appropriate. To avoid complexity, when there are multiple identical components in the same drawing, only one of them may be labeled with a symbol, and not all of them. All drawings are for illustrative purposes only, and the shapes and dimensional ratios of the elements in the drawings do not necessarily correspond to the actual objects.

[0014] 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."

[0015] <β-type Sialon phosphor> The β-sialon phosphor of this embodiment contains Eu. The β-sialon phosphor of this embodiment when EuF3 was used as a reference sample 151 The Mössbauer spectrum of Eu is (i) The first Lorenz curve, whose peak is between -20 and -10 mm / s; (ii) a second Lorenz curve with a peak between -1 and 1 mm / s; (iii) a third Lorenz curve having a peak between the peak of the first Lorenz curve and the peak of the second Lorenz curve; Let's say we fit the three Lorenz curves shown below. The area enclosed by the first Lorenz curve and the baseline is A 2+ year, The area enclosed by the second Lorenz curve and the baseline is A 3+ year, When the area enclosed by the third Lorenz curve and the baseline is A', A 3+ / A 2+ is less than 0.15, and A' / A 2+ is less than 0.36.

[0016] Generally, the Mössbauer spectrum obtained by Mössbauer analysis reflects the electronic state, such as the valence of a specific element in the object to be measured, chemical bonds, elemental arrangement, electron spin, and crystal defects. In terms of measurement principle, Mössbauer analysis is 151 Eu can be detected, 153 Eu is undetectable, and 151 EU: 153 Since the natural abundance ratio of Eu is 48%:52%, it is possible to detect 48% of the Eu state in the measurement target. Generally, isotopes have the same number of protons and orbital electrons, so their chemical properties are almost the same. 151 If the Mössbauer spectrum of Eu can be analyzed, the analysis results will provide important information about the local electronic environment of all Eu in the measurement target.

[0017] According to previous findings on the Mössbauer spectrum of Eu-containing substances and the study by the inventors, when EuF3 was used as the reference sample, 151In the Mössbauer spectrum of Eu, (i) the peak position (isomer shift) of the spectrum due to divalent Eu is usually between -20 and -10 mm / s, specifically between -17 and -10 mm / s. Also, (ii) the peak position (isomer shift) of the spectrum due to trivalent Eu is usually between -1 and 1 mm / s, specifically between -0.5 and 0.5 mm / s. Furthermore, in the Mössbauer spectrum of Eu-containing materials with complex compositions, such as β-SiAlON phosphors, (iii) a spectrum with a peak between the peak positions of (i) and (ii) may be detected due to the presence of Eu, which is probably divalent but has a different charge and electronic state from the divalent Eu in (i) above.

[0018] It is believed that the electronic state of Eu in a β-type sialon phosphor affects the luminescence characteristics. Therefore, the inventors have investigated the luminescence properties of a β-type sialon phosphor when EuF3 is used as a reference sample. 151 The Mössbauer spectrum of Eu was fitted with three Lorentzian curves defined below. (i) The first Lorenz curve with a peak between -20 and -10 mm / s (ii) The second Lorenz curve, whose peak is between -1 and 1 mm / s. (iii) The third Lorenz curve has a peak between the peaks of the first and second Lorenz curves (usually around -8 to -3 mm / s).

[0019] Based on previous findings on the Mössbauer spectra of Eu-containing materials, the first Lorentz curve can be considered to correspond to the Mössbauer spectrum of divalent Eu. The second Lorentz curve can be considered to correspond to the Mössbauer spectrum of trivalent Eu. The third Lorentz curve can be considered to correspond to the Mössbauer spectrum of Eu, which is probably divalent, but whose surrounding charge and electronic state differ from that of the (normal) divalent Eu mentioned above.

[0020] The inventor then defines the area enclosed by the first Lorenz curve and the baseline as A 2+ , the area enclosed by the second Lorenz curve and the baseline is A 3+ The area enclosed by the third Lorentz curve and the baseline was defined as A'. Then, by analyzing the Mössbauer spectra of various β-sialon phosphors with different compositions and manufacturing methods, we investigated whether there was a correlation between the relative size of these areas and the luminescence properties.

[0021] Through consideration, A 3+ A 2+ The smaller A' is compared to A, the better the luminescence characteristics are. 2+ It was inferred that the smaller the value compared to , the better the luminescence characteristics tend to be. Based on this assumption, the inventors further investigated the matter. 3+ / A 2+ is 0.15 or less, and A' / A 2+ We have newly produced a β-SiAlON phosphor with a β-SiAlON value of 0.36 or less. The luminescence properties of this new β-SiAlON phosphor are excellent.

[0022] A 3+ / A 2+ is 0.15 or less, and A' / A 2+ The reason why the luminescence characteristics of a β-sialon phosphor having a value of 0.36 or less are good can be explained as follows. Note that the following explanation includes speculation. Furthermore, the following explanation does not limit the present invention. Based on past knowledge, it is divalent Eu that contributes to the emission of β-SiAlON phosphors. 3+ / A 2+ The fact that is 0.15 or less indicates that the amount of divalent Eu that contributes to luminescence is sufficiently greater than the amount of trivalent Eu that does not contribute to luminescence. The "probably divalent Eu, but with a different surrounding charge and electronic state from normal divalent Eu" corresponding to the third Lorentz curve can be interpreted as excess divalent Eu. If there is too much of this Eu, the energy from the excitation light will turn into heat energy while being transferred between Eu, which is thought to reduce the luminous efficiency. However, if the area A' of the third Lorentz curve is A 2+ , which means that there is relatively little excess divalent Eu. This is thought to reduce the "wasteful transfer of energy between Eu atoms" as described above, thereby improving the luminescence properties.

[0023] Incidentally, research has been conducted in the past to investigate the state of Eu in Eu-containing phosphors using Mössbauer spectroscopy, but most of the previous research has focused on the state of Eu in phosphors with a relatively high Eu content. The present inventors have uniquely identified the state of a small amount of Eu in a β-sialon phosphor by using Mössbauer spectroscopy as described in this specification. There are several methods for accurately measuring the Mössbauer spectrum of a small amount of Eu in a β-sialon phosphor, including increasing the intensity of gamma rays used in the measurement, taking longer to measure and increasing the number of integration times, 151 High Eu content enrichment 151 There are methods using Eu and methods measuring at low temperatures. 151 Eu is commercially available.

[0024] Just to be clear, accurate fitting of Mössbauer spectra using the first to third Lorentz curves is possible using commercially available analysis software, such as the graph processing software "IGOR Pro." For specific fitting methods, see the examples described below.

[0025] The β-sialon phosphor of this embodiment can be manufactured by using appropriate raw materials and employing appropriate manufacturing conditions. One of the key points is to carry out an "annealing step using SrF2." If this annealing step is not carried out, it may not be possible to manufacture the β-sialon phosphor of this embodiment. Details of the manufacturing conditions will be explained later.

[0026] The β-sialon phosphor of this embodiment will be further described.

[0027] (Ratio of the area of ​​each Lorentz curve, peak intensity, full width at half maximum, etc.) As mentioned above, A 3+ / A 2+ should be 0.15 or less. From the perspective of the aforementioned presumed mechanism, A 3+ / A 2+ However, from the practical viewpoint of manufacturing costs, etc., A 3+ / A 2+ can preferably be 0.03 or more. A 3+ / A 2+ is preferably 0.03 to 0.15, more preferably 0.04 to 0.12, and even more preferably 0.05 to 0.10.

[0028] As mentioned above, A' / A 2+ should be 0.36 or less. From the perspective of the aforementioned presumed mechanism, A' / A 2+ However, from the practical viewpoint of manufacturing costs, etc., A' / A 2+ can preferably be 0.20 or more. A' / A 2+ is preferably 0.20 to 0.36, more preferably 0.25 to 0.36, and even more preferably 0.30 to 0.35.

[0029] In this embodiment, A' / A 3+ By setting the value of , it may be possible to expect further improvement in the light-emitting properties. In this embodiment, in the annealing step or other optional steps described in detail later, a portion of the trivalent Eu changes to "probably divalent Eu, but the surrounding charge and electronic state are different from normal divalent Eu," or "probably divalent Eu, but the surrounding charge and electronic state are different from normal divalent Eu" is removed from the system. In other words, the amount of trivalent Eu and the amount of "probably divalent Eu, but the surrounding charge and electronic state are different from normal divalent Eu" vary due to the annealing step or the like, and therefore, A' / A 3+ By focusing on this index and adjusting the raw material composition, manufacturing conditions, etc. so that this index becomes an appropriate value, the luminescence characteristics of the finally obtained β-sialon phosphor may be further improved. Specifically, A' / A 3+ is preferably 1.90 to 5.00, more preferably 2.50 to 5.00, even more preferably 3.00 to 5.00, and particularly preferably 4.00 to 5.00.

[0030] As mentioned above, it is believed that divalent Eu in the β-SiAlON phosphor contributes to its excellent luminescence characteristics. A high ratio of divalent Eu in the β-SiAlON phosphor is believed to further improve the luminescence characteristics. The high ratio of divalent Eu in the β-sialon phosphor means that, for example, 2+ / (A 2+ +A 3+ A 2+ / (A 2+ +A 3+ +A') is preferably 0.70 or more. 2+ / (A 2+ +A 3+ In principle, it is considered preferable that A' is closer to 1. However, from the practical viewpoint of manufacturing costs, A 2+ / (A 2+ +A 3+ +A') is preferably 0.70 to 0.90, more preferably 0.70 to 0.80.

[0031] Also, it is considered that the peak intensity of the first Lorentz curve can also represent that "the ratio of divalent Eu in the β - type sialon phosphor is large". Specifically, when the minimum value of the absorption of the Mössbauer spectrum (before fitting) obtained by measuring the β - type sialon phosphor is set to 0, the peak intensity of the first Lorentz curve is preferably 0.40 or more, more preferably 0.40 to 1.00, still more preferably 0.40 to 0.85, and particularly preferably 0.40 to 0.70. Incidentally, the peak intensity here is the length of the line segment from the peak top to the baseline of the first Lorentz curve when the minimum value is set to 0 and the maximum value is set to 1 for normalization in the Mössbauer spectrum (before fitting).

[0032] The full width at half maximum of the third Lorentz curve can also affect the fluorescence characteristics of the β - type sialon phosphor. As described above, the third Lorentz curve is considered to correspond to the Mössbauer spectrum of "presumably divalent Eu, but Eu with different surrounding charge and electron states from normal divalent Eu". A large full width at half maximum of this (the peak is not sharp but broad) indicates that there are various divalent Eu with slightly different surrounding charge and electron states in the β - type sialon phosphor. Although the details are unclear, the presence of various types of divalent Eu rather than one type in the β - type sialon phosphor may reduce the aforementioned "wasteful energy transfer between Eu" and improve the luminescence characteristics. The full width at half maximum of the third Lorentz curve is preferably 7.00 mm / s or more, more preferably 7.00 to 9.00 mm / s.

[0033] (Composition) The composition of the β - type sialon phosphor of this embodiment is represented by, for example, the general formula: Si 6-Z Al Z O Z N 8-Z :Eu 2+ (0 < Z ≦ 4.2), and Eu 2+ is in solid solution. General formula: Si 6-Z AlZ O Z N 8-Z :EU 2+ In the above, the Z value and the europium content are not particularly limited. Z is, for example, greater than 0 and equal to or less than 4.2, and is preferably 0.005 to 1.0 from the viewpoint of further improving the luminous intensity of the β-sialon phosphor.

[0034] The content of Eu in the β-sialon phosphor of this embodiment is preferably 0.10 to 2.00 mass%, more preferably 0.30 to 1.00 mass%, and even more preferably 0.6 to 0.7 mass%. The content of Eu is not limited, but it is important that the content of Eu is not too high in order to prevent the deterioration of the β-sialon phosphor during the production of the phosphor. 3+ This may lead to the suppression of the generation of "Eu, which is probably divalent but whose surrounding charge and electronic state differ from that of normal divalent Eu."

[0035] (particle size distribution) The β-sialon phosphor of this embodiment is usually in powder form. The volume-based cumulative 50% diameter D of the β-sialon phosphor of this embodiment measured by a laser diffraction scattering method 50 is preferably 10.0 to 40.0 μm, more preferably 15.0 to 30.0 μm. 50 By appropriately controlling D, the light-emitting properties can be further improved. 50 By appropriately controlling the temperature, the handling properties of the β-sialon phosphor powder may be improved.

[0036] <Method of manufacturing β-SiAlON phosphor> The method for producing a β-sialon phosphor containing Eu according to the present embodiment includes the steps of: a firing step of firing a raw material powder obtained by mixing a europium compound, silicon nitride, and aluminum nitride to obtain a fired product; an annealing step of annealing the mixture of the fired product and SrF2 to obtain an annealed fired product; an acid treatment step of treating the annealed fired product with acid; Includes.

[0037] The above-mentioned A 3+ / A 2+ is 0.15 or less, and A' / A 2+ A β-sialon phosphor having a β-SiAlON content of 0.36 or less can be preferably produced by such a production method.

[0038] The firing step, the annealing step, and any other optional steps will be described below.

[0039] (Firing process) The specific conditions for the firing step are not particularly limited, as long as a fired product (β-sialon phosphor) can be obtained by firing a raw material powder mixture of a europium compound, silicon nitride, and aluminum nitride. Examples of europium compounds include metal, oxides, carbonates, halides, nitrides, and oxynitrides of Eu. Firing can be carried out in one step or in two separate steps. When performing the firing in two separate steps, the raw materials are blended so that the final fired product has the composition of a β-sialon phosphor. At this time, the amount of oxide contained in the silicon nitride powder or aluminum nitride powder must also be taken into consideration. To adjust the amount of oxygen derived from the raw materials, silicon oxide (SiO2), aluminum oxide (Al2O3), metallic silicon, or metallic aluminum may be used.

[0040] The raw materials can be mixed to obtain a raw material powder by dry mixing, wet mixing in an inert solvent that does not substantially react with the raw material components, and then removing the solvent, etc. Suitable mixing devices include a V-type mixer, a rocking mixer, a ball mill, and a vibration mill.

[0041] The raw material powder is filled into a container such as a crucible, preferably made of boron nitride, and heated in an inert atmosphere such as a nitrogen atmosphere at a temperature of preferably 1550 to 2100°C. This promotes the reaction within the raw material powder. If the firing is carried out in two separate steps, the production rate of β-sialon is not important as long as it is partially produced at this stage.

[0042] When firing is performed in two stages, the sample obtained in the first firing (first fired powder) may be in powder form or in clumps depending on the raw material composition and firing temperature. Therefore, if necessary, it is crushed or disintegrated into a powder form that can pass through a sieve with 45 μm openings, for example. When firing is performed in two stages, one or more materials selected from the group consisting of silicon nitride, silicon oxide, aluminum nitride, aluminum oxide, and europium oxide can be added to the first fired powder. Then, the materials are mixed and filled into a container in the same manner as above, and the second firing is performed. The second firing is preferably performed in an inert atmosphere such as a nitrogen atmosphere, preferably at a temperature of 1900 to 2100°C.

[0043] In this manner, a β-sialon containing Eu in a solid solution can be obtained. If the fired product after the second firing is in a lumpy state, it is preferable to crush and / or disintegrate it into a powder state.

[0044] (Annealing process) In the annealing step, the mixture of the fired product obtained in the firing step and SrF2 is annealed, thereby obtaining an annealed fired product (β-type Sialon phosphor). Although the details are unclear, it is thought that annealing converts at least a portion of the trivalent Eu in the fired material to divalent Eu. The addition of SrF2 is thought to be effective in removing "Eu that is probably divalent but whose surrounding charge and electronic state differ from that of normal divalent Eu."

[0045] From the viewpoint of fully obtaining the effect of using SrF2 as an additive and from the viewpoint of minimizing the disadvantages of using SrF2, the amount of SrF2 used is preferably 0.01 to 15.0 parts by mass, more preferably 0.1 to 1.5 parts by mass, per 100 parts by mass of the fired product obtained in the firing step. The method for mixing the fired product and SrF2 is not particularly limited, and for example, the method for mixing raw material powders in the firing step can be adopted.

[0046] The atmosphere for the annealing step is preferably a noble gas or a reducing gas. Noble gases are, for example, gases of Group 18 elements such as argon and helium. Reducing gases are, for example, gases with reducing power such as ammonia, carbon monoxide, and hydrogen. The reducing gas may be used alone or may be mixed with a neutral gas such as nitrogen or a rare gas.

[0047] The temperature of the annealing step is preferably 1350 to 1750°C, more preferably 1450 to 1600°C, from the viewpoint of sufficiently reducing the amount of trivalent Eu in the fired product and the amount of "Eu that is probably divalent but whose surrounding charge and electronic state are different from normal divalent Eu," and from the viewpoint of suppressing decomposition of β-sialon. From the same viewpoint, the time for the annealing step is preferably 4 to 12 hours, more preferably 6 to 10 hours.

[0048] (Other optional steps) It is preferable to further carry out a step of treating the fired product (β-type sialon phosphor) after the annealing step with an acid, an alkali and / or a fluorine. The acid treatment or alkali treatment is, for example, a treatment in which an acidic or alkaline liquid is brought into contact with the fired product that has undergone the annealing step, and the fluorine treatment is, for example, a treatment in which a fluorine-containing gas is brought into contact with the fired product that has undergone the annealing step. By carrying out such a process, it is believed that it is possible to dissolve or remove at least a part of the hetero-phase components (luminescence inhibitors) generated during the firing and annealing processes, and in some cases, it is possible to further improve the luminescence characteristics of the β-sialon phosphor.

[0049] The acidic liquid may be, for example, an aqueous solution containing one or more acids selected from hydrofluoric acid, sulfuric acid, phosphoric acid, hydrochloric acid, and nitric acid. The alkaline liquid may be, for example, an aqueous solution containing one or more alkalis selected from potassium hydroxide, aqueous ammonia, and sodium hydroxide. An acidic aqueous solution is more preferable, and a mixed aqueous solution of hydrofluoric acid and nitric acid is particularly preferable.

[0050] The treatment method using an acidic or alkaline liquid is not particularly limited, but can be carried out by dispersing the fired product or an annealed fired product in an aqueous solution containing an acid or alkali and stirring for several minutes to several hours (for example, 10 minutes to 6 hours). A known stirrer or the like can be used for stirring. The temperature during stirring is, for example, 50 to 100°C, preferably 65 to 85°C (the liquid is maintained at this temperature). The stirring time is, for example, 1 minute to 2 hours, preferably about 10 minutes to 1 hour. The stirring speed is, for example, 300 to 600 rpm, preferably 400 to 500 rpm. After this treatment, it is desirable to separate substances other than the β-sialon phosphor by filtration, and then wash the substances adhering to the β-sialon phosphor with water and dry it thoroughly.

[0051] <Composite, wavelength conversion member, and light-emitting device> The composite of this embodiment includes the above-mentioned β-sialon phosphor and a sealant that seals the β-sialon phosphor. Moreover, the wavelength conversion member of this embodiment includes the above-mentioned composite. The light emitting device of this embodiment also includes the wavelength conversion member described above, and a light source capable of emitting excitation light that excites the β-sialon phosphor in the wavelength conversion member to emit light.

[0052] An example of the composite and the light emitting device will be described below with reference to FIG. The light emitting device includes a light source and a wavelength conversion member. The wavelength conversion member includes the above-mentioned β-sialon phosphor. Preferably, the wavelength conversion member comprises a composite including the above-mentioned β-sialon phosphor and a sealant that seals the β-sialon phosphor.

[0053] FIG. 1 is a cross-sectional view showing a schematic example of the structure of a light emitting device 10. As shown in FIG. 1 is formed of an LED chip as a light source 12, a first lead frame 13 on which the light source 12 is mounted, a second lead frame 14, a wavelength conversion member 15 that covers the light source 12, a bonding wire 16 that electrically connects the light source 12 and the second lead frame 14, and a synthetic resin cap 19 that covers these. The wavelength conversion member 15 has a phosphor 18 and a sealing resin 17 in which the phosphor 18 is dispersed.

[0054] A recess 13b is formed in the upper portion 13a of the first lead frame 13 for mounting a light emitting diode chip as the light source 12. The recess 13b has a generally funnel shape with a hole diameter gradually increasing from the bottom surface toward the top, and the inner surface of the recess 13b serves as a reflective surface. An electrode on the lower surface of the light emitting source 12 is die-bonded to the bottom surface of this reflective surface. The other electrode formed on the upper surface of the light emitting source 12 is connected to the surface of the second lead frame 14 via a bonding wire 16.

[0055] Various types of LED chips can be used as the light source 12. Particularly preferred is an LED chip that emits light with a wavelength of 300 nm or more and 500 nm or less, which is from near ultraviolet to blue light.

[0056] At least a part of the phosphor 18 contained in the wavelength conversion member 15 of the light emitting device 10 is the above-mentioned β-sialon phosphor. From the viewpoint of controlling the emission wavelength of the light emitting device 10, the phosphor 18 may further contain, in addition to the β-sialon phosphor, phosphors such as an α-sialon phosphor, a KSF-based phosphor, CaAlSiN3, or a simple substance or a mixture of YAG. Examples of elements that are dissolved in these phosphors include europium (Eu), cerium (Ce), strontium (Sr), calcium (Ca), and manganese (Mn). These phosphors may be used singly or in combination of two or more. Among these, KSF-based phosphors containing manganese as a solid solution are preferred as phosphors to be used in combination with β-SiAlON phosphors. By combining a green β-SiAlON phosphor with a red KSF-based phosphor, it is possible to configure an LED for backlighting suitable for, for example, high color rendering TVs. Just to be clear, KSF phosphors containing manganese in solid solution have the general formula: A2M (1-n) F6:Mn 4+ n In this general formula, the element A is one or more alkali metal elements containing K, the element M is Si alone, Ge alone, or a combination of Si with one or more elements selected from the group consisting of Ge, Sn, Ti, Zr, and Hf, and 0 <n≦0.1である。

[0057] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0058] The embodiments of the present invention will be described in detail based on Examples and Comparative Examples. However, it should be noted that the present invention is not limited to the Examples.

[0059] <Production of β-type Sialon phosphor> Example 1 Firing process First, the following raw materials were mixed using a V-type mixer (S-3 manufactured by Tsutsui Scientific Instruments Co., Ltd.), and then passed through a sieve with 250 μm openings to remove agglomerates, thereby obtaining raw material powder. The compounding ratio (first compounding composition) here is the general formula of β-sialon: Si 6-z Al z O z N 8-z In this case, the material was designed so that z=0.25 calculated from the Si / Al ratio, excluding europium oxide. Ube Industries α-type silicon nitride powder (SN-E10 grade, oxygen content 1.0% by mass) 95.43% by mass Tokuyama Aluminum Nitride Powder (F Grade, oxygen content 0.8% by mass) 3.04% by mass Aluminum oxide powder (TM-DAR grade) manufactured by Taimei Chemical Industry Co., Ltd. 0.74% by mass Europium oxide powder (RU grade) manufactured by Shin-Etsu Chemical Co., Ltd. 0.79% by mass

[0060] 200 g of the raw material powder was packed into a cylindrical boron nitride container (manufactured by Denka, N-1 grade) with a lid, having an inner diameter of 10 cm and a height of 10 cm. Then, in an electric furnace equipped with a carbon heater, heat treatment (first firing) was carried out at 1800°C for 4 hours in a pressurized nitrogen atmosphere of 0.8 MPa. The heat-treated powder was then passed through a sieve with 45 μm openings. All of the powder passed through the sieve. The sieved powder (referred to as the first fired powder) was blended with the raw material mixed powder having the first blending composition described above in a mass ratio of 1:1 (second blending composition), and mixed in a V-type mixer in the same manner as above to obtain a mixed powder. 200 g of this mixed powder was filled into a cylindrical boron nitride container with a lid, measuring 10 cm in inner diameter and 10 cm in height, and heat-treated (second firing) in an electric furnace equipped with a carbon heater in a pressurized nitrogen atmosphere of 0.8 MPa at 2000°C for 12 hours. After the heat treatment, the sample was in the form of loosely agglomerated lumps. Therefore, these lumps were roughly crushed with a hammer. Then, the sample was crushed using a supersonic jet crusher (PJM-80SP, manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain crushed powder. The crushing conditions were a sample supply rate of 50 g / min and a crushing air pressure of 0.3 MPa. The crushed powder was then passed through a sieve with 45 μm openings. The sieve passing rate was 95%. Hereinafter, this powder will be referred to as the second fired powder.

[0061] Annealing process 0.5 parts by mass of SrF2 (manufactured by Kojundo Chemical Co., Ltd.) was weighed out per 100 parts by mass of the second calcined powder and mixed with the second calcined powder to obtain a mixed powder. The total amount of the mixed powder was 20 g. The mixing method was the same as the method used to obtain the raw material powder in the calcination process. Then, 20 g of the mixed powder was passed through a sieve with 250 μm openings and filled into a cylindrical boron nitride container with a lid, measuring 5 cm in inner diameter and 3.5 cm in height, and annealed in an electric furnace with a carbon heater in an argon atmosphere at atmospheric pressure at 1500°C for 8 hours. The sample after annealing was in the form of loosely agglomerated lumps. Therefore, these lumps were crushed using a hammer and a mortar, and the sieves were passed through a 75 μm sieve. This powder is referred to as annealed powder.

[0062] Acid treatment process The annealed powder was acid-treated by immersing it in a 1:1 mixture of 50% hydrofluoric acid and 70% nitric acid at 75°C for 30 minutes. The acid-treated powder was then precipitated, the supernatant and fine powder were removed, and the precipitate was dispersed in pure water again, followed by precipitation. This decantation process was repeated until the pH of the solution reached 5 or higher and the supernatant became transparent. The final precipitate was then filtered and dried. In this way, the β-sialon phosphor of Example 1 was obtained. The resulting β-sialon phosphor was subjected to powder X-ray diffraction analysis, and the results showed that the crystalline phase present was a single β-sialon phase.

[0063] Example 2 A β-sialon phosphor of Example 2 was obtained in the same manner as in Example 1, except that the "annealing step" was changed as follows.

[0064] 0.05 parts by mass of SrF2 (manufactured by Kojundo Chemical Co., Ltd.) was weighed out relative to 100 parts by mass of the second fired powder and mixed with the second fired powder. The total amount of the mixed powder was 20 g. The mixing method was the same as that used to prepare the fired powder. Then, 20 g of the mixed powder was passed through a sieve with 250 μm openings and filled into a cylindrical boron nitride container with a lid, measuring 5 cm in inner diameter and 3.5 cm in height, and annealed in an electric furnace with a carbon heater in an argon atmosphere at atmospheric pressure at 1500°C for 8 hours. The sample after annealing was in the form of loosely agglomerated lumps. Therefore, these lumps were crushed using a hammer and a mortar, and the sieves were passed through a 75 μm sieve. This powder is referred to as annealed powder.

[0065] (Comparative Example 1) A β-sialon phosphor of Comparative Example 1 was obtained in the same manner as in Example 1, except that in the "annealing step", SrF2 was not used and 20 g of the second fired powder was directly annealed.

[0066] (Comparative Example 2) A β-sialon phosphor of Comparative Example 2 was obtained in the same manner as in Example 1, except that the "annealing step" was not carried out and 20 g of the second fired powder was directly subjected to the acid treatment.

[0067] <Mössbauer spectroscopy> The β-sialon phosphor was subjected to Mössbauer spectroscopy under the following analytical conditions: γ-ray source: Sealed source 151 Sm Measurement period: Approximately 2 months per sample Preparation of the measurement sample: Mix the powder with grease, spread it, and sandwich it between two pieces of film (2.5 mm thick) Measurement speed range: ±30 mm / s (normalized with reference materials Fe and EuF3) (The measurement velocity range is the range of Doppler velocities given to the radiation source, and is the range of the horizontal axis of the graph shown below.) Measurement temperature: room temperature Source-sample distance: 30 mm Sample-detector distance: 8 mm

[0068] Prior to measuring the measurement sample, a standard sample of EuF3 was measured to calibrate it, indicating a relative velocity of 0 mm / s for trivalent Eu. After that, the sample was measured and a Mössbauer spectrum was obtained, with the horizontal axis representing the relative velocity and the vertical axis representing the transmittance (relative value). Incidentally, in this spectroscopic analysis, the Eu concentration in the β-sialon phosphor was relatively low, so the measurement time was about two months as described above, so that the number of accumulations was large.

[0069] <Fitting of Mössbauer spectra with Lorentzian curves> Using the graph processing software IGOR Pro 6.0 (hereinafter abbreviated as "IGOR Pro") from HULINKS, the Mössbauer spectrum was fitted with three Lorentzian curves. The fitting procedure is outlined below. (1) The Mössbauer spectrum data obtained above was imported into IGOR Pro, and the Mössbauer spectrum was plotted on the screen. (2) The initial baseline value for fitting was set based on the transmittance value of the portion of the plotted Mössbauer spectrum where the relative velocity is greater than or equal to 0. Incidentally, based on past knowledge, it is almost impossible to observe Eu species with a relative velocity greater than or equal to 0 in the Mössbauer spectrum of Eu, so it is reasonable to set the transmittance value of the portion with a relative velocity greater than or equal to 0 as the initial baseline value. In addition, based on the position of the plotted Mössbauer spectrum where the transmittance is minimum between relative velocities of -20 and -10 mm / s, the peak position (relative velocity) of the first Lorentz curve and the initial value of the peak intensity from the initial value of the baseline were set. Furthermore, based on the findings of previous Mössbauer analyses of Eu-containing samples and the general shape of the drawn Mössbauer spectrum, initial values ​​were set for (i) the full width at half maximum of the first Lorentz curve, (ii) the peak position (relative velocity), peak intensity and full width at half maximum from the initial value of the baseline of the second Lorentz curve, and (iii) the peak position (relative velocity), peak intensity and full width at half maximum from the initial value of the baseline of the third Lorentz curve. (3) Using the regression analysis function of IGOR Pro, the peak positions, peak intensities, and full widths at half maximum of the first, second, and third Lorentz curves were optimized. Specifically, the peak positions, peak intensities, and full widths at half maximum of the first, second, and third Lorentz curves were adjusted and optimized so that the "chi-squared (V_chisq)" value calculated by IGOR Pro based on the difference between the baseline whose initial value was set in (2) above, the composite curve which is the sum of the first, second, and third Lorentz curves, and the Mössbauer spectrum data, was sufficiently small (approximately 3 or less, preferably 2 or less).

[0070] (supplement) The inventors have found that if the initial settings of the baseline, the peak position (relative velocity) of the first Lorenz curve, and the initial value of the peak intensity from the initial value of the baseline in (2) above are appropriate, then even if the other initial settings are somewhat rough, by repeatedly performing regression analysis, it is possible to ultimately achieve fitting with sufficient accuracy. In this fitting, the regression analysis in (3) above was performed semi-automatically by creating a program in IGOR Pro. However, even without creating a program, it is possible to achieve fitting with sufficient accuracy by creating and combining multiple Lorenz functions in Excel or similar, and then using the solver function to fine-tune the parameters of the first, second, and third Lorenz curves so that the chi-square value and residual sum of squares of the combined function are small. The fitting of Mössbauer spectra using the method described here is a standard technique that has also been used by the group of Professor Yasuhiro Yamada of the Tokyo University of Science, Faculty of Science II, who is famous for Mössbauer spectroscopy, and is not something special.

[0071] As described above, in the Mössbauer spectra of the examples and comparative examples, the first Lorentz curve, the second Lorentz curve, the third Lorentz curve, and the baseline were obtained. Then, using the function of IGOR Pro, the area A enclosed by the first Lorentz curve and the baseline 2+ and the area A enclosed by the second Lorentz curve and the baseline 3+ and the area A' enclosed by the third Lorentz curve and the baseline were calculated. At this time, A 2+ and A 3+ and the values of A' were calculated as relative values with A 2+ + A 3+ + A' = 100.

[0072] For reference, the Mössbauer spectra and fitting functions of the β - sialon phosphors of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 are shown in FIGS. 2 to 5.

[0073] <Measurement of Eu Content (Fluorescent X - ray Analysis)> The Eu content in the β - sialon phosphor was determined by fluorescent X - ray analysis.

[0074] <Measurement of Particle Size Distribution> The particle size distribution of the β - sialon phosphor was measured by the laser diffraction scattering method in accordance with JIS R1629:1997 using Microtrac MT3300EX II (Microtrac Bell Co., Ltd.). The pretreatment of the measurement sample was as follows. 0.5 g of the β - sialon phosphor was added to 100 mL of ion - exchanged water, and dispersion treatment was performed for 3 minutes using an Ultrasonic Homogenizer US - 150E (Nippon Seiki Co., Ltd., chip size φ20 mm, Amplitude 100%, oscillation frequency 19.5 KHz, amplitude of about 31 μm). This was used as the measurement sample. The particle size distribution of the measurement sample was measured using the above - mentioned apparatus. From the obtained particle size distribution, D 50 was determined.

[0075] <Evaluation> (Peak intensity and peak wavelength of light emission) Measurement was performed using a spectrofluorometer (Hitachi High-Technologies Corporation, F-7000) calibrated with the Rhodamine B method and a standard light source. Specifically, the β-sialon phosphor was first loaded into a dedicated solid sample holder. Then, using a spectrofluorometer, the fluorescence spectrum was measured when the phosphor was irradiated with excitation light split at a wavelength of 455 nm. The peak intensity and peak wavelength were determined from the obtained fluorescence spectrum.

[0076] Just to be clear, the units used are arbitrary because the emission peak intensity varies depending on the measurement device and conditions. In this study, the β-sialon phosphors of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 were measured under the same conditions and compared. Table 2 below shows the relative values ​​(%), with the peak intensity of the standard sample (YAG phosphor P46Y3 manufactured by Mitsubishi Chemical Corporation) set at 100%.

[0077] (Absorption rate, internal quantum efficiency, and external quantum efficiency of light with a wavelength of 455 nm) A standard reflector plate (Spectralon (registered trademark) manufactured by Labsphere) with a reflectance of 99% was set at the side opening of the integrating sphere. Monochromatic light separated into 455 nm wavelengths from a light source (Xe lamp) was introduced into the integrating sphere via an optical fiber. The reflected light spectrum was measured using a spectrophotometer (MCPD-7000, manufactured by Otsuka Electronics Co., Ltd.). The number of excitation light photons (Qex) was calculated from the spectrum in the wavelength range of 450 to 465 nm.

[0078] Next, the β-SiAlON phosphor was filled into a concave cell so that the surface was smooth, and the cell was placed in the opening of the integrating sphere. Monochromatic light with a wavelength of 455 nm was then irradiated onto the β-SiAlON phosphor, and the excitation reflection spectrum was measured using a spectrophotometer. The number of reflected excitation photons (Qref) and the number of fluorescent photons (Qem) were calculated from the obtained spectral data. The number of reflected excitation photons was calculated in the same wavelength range as the number of excitation photons, and the number of fluorescent photons was calculated in the range of 465 to 800 nm. From the obtained numbers of the three types of photons, the external quantum efficiency, the light absorption rate, and the internal quantum efficiency were calculated based on the following formulas. Absorbance of excitation light at 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 Internal quantum efficiency (%) = External quantum efficiency / Absorption rate of excitation light at a wavelength of 455 nm

[0079] (Absorption rate of light with a wavelength of 600 nm) A standard reflector plate (Spectralon (registered trademark) manufactured by Labsphere) with a reflectance of 99% was set at the side opening of the integrating sphere. Monochromatic light separated into wavelengths of 600 nm from a light source (Xe lamp) was introduced into the integrating sphere via an optical fiber. The reflected light spectrum was measured using a spectrophotometer (MCPD-7000, manufactured by Otsuka Electronics Co., Ltd.). The number of incident light photons (Qex(600)) was calculated from the spectrum in the wavelength range of 590 to 610 nm. Next, the β-SiAlON phosphor was filled into a concave cell so that the surface was smooth, and the cell was placed in the opening of the integrating sphere. Monochromatic light with a wavelength of 600 nm was then irradiated onto the β-SiAlON phosphor, and the incident and reflected light spectrum was measured using a spectrophotometer. The incident reflected light photon count (Qref(600)) was calculated from the obtained spectral data. The incident reflected light photon count (Qref(600)) was calculated in the same wavelength range as the incident light photon count (Qex(600)). The 600 nm light absorptance was calculated from the obtained two types of photon counts using the following formula. 600 nm light absorption rate = ((Qex(600) - Qref(600)) / Qex(600)) × 100

[0080] (diffuse reflectance) The diffuse reflectance of the β-sialon phosphor was measured using an ultraviolet-visible spectrophotometer (V-550) manufactured by JASCO Corporation equipped with an integrating sphere device (ISV-469). Baseline correction was performed using a standard reflector (Spectralon), a solid sample holder filled with β-type sialon phosphor was set, and diffuse reflectance was measured in the wavelength range of 500 to 800 nm.

[0081] Table 1 shows the information obtained based on the fitting of the Mössbauer spectrum, the Eu content, and the particle size distribution measurement results. Table 2 shows the evaluation results of the luminescence characteristics of the β-sialon phosphor. (supplement) As mentioned above, the "peak intensity" in Table 1 refers to the length of the line segment from the peak top to the baseline of each Lorentz curve when the minimum value in the Mössbauer spectrum (before fitting) is normalized to 0 and the maximum value to 1. (The baseline value is also the value obtained by normalizing the minimum value of the Mössbauer spectrum (before fitting) to 0 and the maximum value to 1.) In all examples and comparative examples, the final chi-squared value was 3 or less as a result of fitting. In other words, the Mössbauer spectrum was able to be fitted (approximated) with three Lorentzian curves with a sufficiently high degree of accuracy. (Incidentally, although it depends on various conditions, when the chi-squared value is 3.8415 or less, it can be determined that the fitting function fits the raw data sufficiently well. The basis for "3.8415" is described, for example, at https: / / www.business-research-lab.com / 220705-2 / .)

[0082] [Table 1]

[0083] [Table 2]

[0084] (Explanation of results) As shown in the table above, A 3+ / A 2+ is 0.15 or less, and A' / A 2+ The β-sialon phosphors of Examples 1 and 2, in which the λ value was 0.36 or less, exhibited good internal quantum efficiency and external quantum efficiency, etc. In other words, the β-sialon phosphors of Examples 1 and 2 had good light-emitting properties. In contrast, A' / A 2+ The β-sialon phosphor of Comparative Example 1, in which A is larger than 0.36, 3+ / A 2+ The luminescence characteristics of the β-sialon phosphor of Comparative Example 2, in which the value was larger than 0.15, were inferior to those of the β-sialon phosphors of Examples 1 and 2. From the comparison between these Examples and Comparative Examples, the luminescence characteristics of the β-sialon phosphor are as follows: 3+ / A 2+ is 0.15 or less, and A' / A 2+ It is understood that the improvement is achieved by satisfying both that

[0085] Incidentally, due to the difference in manufacturing methods between the examples and comparative examples, 3+ / A 2+ is 0.15 or less, and A' / A 2+ It is understood that in order to manufacture a β-sialon phosphor having a β-SiAlON ...

[0086] (Additional information about Comparative Example 1) Comparative Example 1 is an example in which the annealing step was carried out without using any additive substance such as SrF2. Annealing processes that do not use additives have been conventionally performed in the manufacture of β-sialon phosphors. In the examples of the aforementioned Patent Document 1 (JP 2018-002870 A), no additives are used in the annealing process. Therefore, it can be said that Comparative Example 1 corresponds to a β-sialon phosphor obtained by an annealing process that does not use additives, as described in the examples of Patent Document 1. [Explanation of symbols]

[0087] 10 Light-emitting device 12 Light source (LED chip) 13 First lead frame 13a Upper 13b Recess 14 Second lead frame 15 Wavelength conversion material 16 Bonding Wire 17 Sealing resin 18 Phosphor (β-type sialon phosphor particles) 19 Cap

Claims

1. A β-sialon phosphor containing Eu, EUF ３ The β-sialon phosphor when the reference sample is １５１ The Mössbauer spectrum of Eu is (i) a first Lorenz curve whose peak is between −20 and −10 mm / s; (ii) a second Lorenz curve whose peak is between -1 and 1 mm / s; (iii) a third Lorenz curve having a peak between the peak of the first Lorenz curve and the peak of the second Lorenz curve; When fitting with the three Lorenz curves, The area enclosed by the first Lorenz curve and the baseline is A. ２＋ year, The area enclosed by the second Lorenz curve and the baseline is A. ３＋ year, When the area enclosed by the third Lorenz curve and the baseline is A', A ３＋ / A ２＋ is less than or equal to 0.15, A' / A ２＋ is 0.36 or less.

2. 2. The β-sialon phosphor according to claim 1, A ３＋ / A ２＋ is 0.03 or more.

3. 3. The β-sialon phosphor according to claim 1 or 2, A' / A ２＋ is 0.20 or more.

4. 3. The β-sialon phosphor according to claim 1 or 2, A' / A ３＋ is 1.90 to 5.

00.

5. 3. The β-sialon phosphor according to claim 1 or 2, A ２＋ / (A ２＋ +A ３＋ +A') is 0.70 or more.

6. 3. The β-sialon phosphor according to claim 1 or 2, A β-sialon phosphor, wherein the peak intensity of the first Lorentz curve is 0.40 or more when the baseline of the Mössbauer spectrum is set to 0.

7. 3. The β-sialon phosphor according to claim 1 or 2, A β-sialon phosphor, wherein the full width at half maximum of the third Lorentz curve is 7.00 mm / s or more.

8. 3. The β-sialon phosphor according to claim 1 or 2, A β-sialon phosphor having an Eu content of 0.10 to 2.00 mass %.

9. 3. The β-sialon phosphor according to claim 1 or 2, Volume-based cumulative 50% diameter D measured by laser diffraction scattering method ５０ A β-sialon phosphor having a particle size of 10.0 to 40.0 μm.

10. A composite comprising the β-sialon phosphor according to claim 1 or 2 and a sealant that seals the β-sialon phosphor.

11. A wavelength conversion member comprising the composite according to claim 10.

12. A light emitting device comprising: the wavelength conversion member according to claim 11; and a light source capable of emitting excitation light that excites the β-sialon phosphor in the wavelength conversion member to emit light.

13. A method for producing a β-sialon phosphor containing Eu, comprising: a firing step of firing a raw material powder obtained by mixing a europium compound, silicon nitride, and aluminum nitride to obtain a fired product; The fired product and SrF ２ an annealing step of annealing the mixture to obtain an annealed fired product; an acid treatment step of treating the annealed fired product with acid; A method for producing a β-sialon phosphor, comprising:

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