Method for manufacturing sintered body and sintered body

Abstract

A method for producing a sintered body and a sintered body are provided. The present invention provides a method for producing a green body by preparing α-sialon phosphor particles, and molding a raw material mixture obtained by mixing the α-sialon phosphor particles and yttrium oxide particles. The method for producing a sintered body includes placing the molded body in a container containing pyrolytic boron nitride, placing a first lid containing pyrolytic boron nitride on the opening of the container, and performing a primary firing of the molded body in the container with the opening closed by the first lid at a temperature in the range of 1800°C to 2000°C to obtain a first sintered body containing an α-sialon phosphor crystal phase.

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing a sintered body and the sintered body. [Background technology]

[0002] Light-emitting devices are known that include a light-emitting diode (LED) or a laser diode (LD) and a wavelength conversion member containing a phosphor that converts the wavelength of light emitted from the LED or LD. Such light-emitting devices are used, for example, as light sources for in-vehicle lighting, general lighting, backlights for liquid crystal display devices, projectors, etc.

[0003] As an example of a wavelength conversion member provided in a light emitting device, Patent Document 1 discloses a wavelength conversion member made of a sintered body obtained by mixing glass powder and inorganic phosphor powder, melting the glass powder, and solidifying it. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-234487

[0005] However, in the case of sintered bodies containing glass components, the glass components may be mixed into the inorganic phosphor during the formation of the sintered body, which may interfere with the light emission of the phosphor. Furthermore, glass has a relatively low softening point, and when irradiated with high-power LED or LD light, the sintered body, which is made by melting and solidifying glass powder mixed with inorganic phosphor powder, may not be able to withstand high temperatures. Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present disclosure is to provide a method for producing a sintered body that has a high relative density and is capable of emitting light with a high luminous flux, and the sintered body. [Means for solving the problem]

[0007] The first aspect is a method for producing a sintered body, comprising: preparing α-sialon phosphor particles; molding a raw material mixture of the α-sialon phosphor particles and yttrium oxide particles to prepare a molded body; placing the molded body in a container containing pyrolytic boron nitride; placing a first lid containing pyrolytic boron nitride on the opening of the container; and performing a primary firing of the molded body in the container, the opening of which is blocked by the first lid, at a temperature in the range of 1800°C or higher and 2000°C or lower, to obtain a first sintered body containing the α-sialon phosphor. Heat ka

[0008] The second embodiment is a sintered body containing an α-sialon phosphor crystal phase and having a relative density of 96% or more. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a method for producing a sintered body that has a high relative density and is capable of emitting light with a high luminous flux. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a flowchart showing steps of a method for producing a sintered body. [Figure 2] 1 is a flowchart showing steps of a method for producing a sintered body. [Figure 3] FIG. 1 is a diagram showing area A in the xy chromaticity coordinates of the CIE 1931 chromaticity diagram. [Figure 4A] FIG. 1 is a schematic plan view illustrating an example of a light emitting device. [Figure 4B] FIG. 1 is a schematic cross-sectional view showing an example of a light-emitting device. [Figure 5] FIG. 1 is a diagram showing the reflectance spectrum of an α-sialon phosphor particle. [Figure 6] FIG. 1 is a cross-sectional view schematically illustrating a compact placed in a container containing pyrolytic boron nitride. [Figure 7A] 10 is a photograph showing the appearance of the main surface of the first sintered body after slicing in Example 1-4. [Figure 7B]1 is a photograph showing the appearance of the main surface of the second sintered body of Example 1-4. [Figure 8] FIG. 1 is a cross-sectional view schematically illustrating a compact placed in a container containing pyrolytic boron nitride. [Figure 9] 10 is a photograph showing the appearance of the first sintered body of Example 7. [Figure 10] 10 is a photograph showing the appearance of a first sintered body sliced ​​into a plate in Example 7. [Figure 11] 10 is a photograph showing the appearance of the main surface of the second sintered body of Example 7. DETAILED DESCRIPTION OF THE INVENTION

[0011] The manufacturing method of a sintered body and the sintered body according to the present disclosure will be described below based on embodiments. However, the embodiments shown below are examples for embodying the technical concept of the present invention, and the present invention is not limited to the manufacturing method of a sintered body and the sintered body described below. The relationship between color names and chromaticity coordinates, and the relationship between light wavelength ranges and color names of monochromatic light, conforms to JIS Z8110. In this specification, the content of each component in a composition means the total amount of the multiple substances present in the composition when multiple substances corresponding to each component are present in the composition, unless otherwise specified.

[0012] The method for manufacturing a sintered body includes preparing α-sialon phosphor particles, molding a raw material mixture of the α-sialon phosphor particles and yttrium oxide particles to prepare a molded body, placing the molded body in a container containing pyrolytic boron nitride (hereinafter also referred to as "PBN (Pyrolytic Boron Nitride)"), placing a first lid containing pyrolytic boron nitride on the opening of the container, and performing a primary firing on the molded body in the container whose opening is closed by the first lid at a temperature in the range of 1800°C or higher and 2000°C or lower to obtain a first sintered body containing an α-sialon phosphor crystalline phase.

[0013] 1 is a flowchart showing an example of a method for producing a sintered body. The method for producing a sintered body includes the steps of preparing α-sialon phosphor particles (S101), molding a raw material mixture of the α-sialon phosphor particles and yttrium oxide particles to prepare a molded body (S102), placing the molded body in a container containing pyrolytic boron nitride (S103), placing a first lid containing pyrolytic boron nitride on the opening of the container (S104), and primarily firing the molded body at a temperature of 1800°C to 2000°C (S105) to obtain a first sintered body containing an α-sialon phosphor crystal phase.

[0014] The method for producing the sintered body includes preparing α-sialon phosphor particles.

[0015] In preparing the α-sialon phosphor particles, the α-sialon phosphor particles have a BET specific surface area of ​​2.0 m 2 / g or more, and the reflectance of light at a wavelength of 450 nm is preferably 30% or more. 2 / g or more, the BET specific surface area of ​​the α-sialon phosphor particles is relatively large, and when preparing a compact containing the α-sialon phosphor particles, the contact area between the α-sialon phosphor particles or between the α-sialon phosphor particles and yttrium oxide particles is relatively large, and by primary firing the compact in a container containing pyrolytic boron nitride, a dense sintered body with a high relative density can be obtained. 2 The α-sialon phosphor particles preferably have a BET specific surface area of ​​5.0 m / g or less. 2 When the BET specific surface area of ​​the α-sialon phosphor particles is 2.0 m / g or less, the α-sialon phosphor particles and the yttrium oxide particles can be easily mixed, and a green body can be prepared by molding a raw material mixture in which the α-sialon phosphor particles and the yttrium oxide particles are mixed almost uniformly. 2If the BET specific surface area is 2.1 m / g or more, the α-sialon phosphor particles are closely bonded together when molded into a raw material mixture, resulting in a high-density molded body. Because the α-sialon phosphor particles in the molded body are closely bonded together, a dense sintered body with high relative density can be obtained by primary firing in a container containing pyrolytic boron nitride. The α-sialon phosphor particles have a BET specific surface area of ​​2.1 m 2 / g or more is more preferable, and 2.2m 2 / g or more is more preferable, and 2.3m 2 The α-sialon phosphor particles preferably have a BET specific surface area of ​​4.5 m / g or more. 2 / g or less is more preferable, and 4.0m 2 / g or less is more preferable, and 3.5m 2 It is even more preferable that the .beta. / g or less.

[0016] If the reflectance of α-sialon phosphor particles at a wavelength of 450 nm is 30% or more, the α-sialon phosphor particles, which are the raw material for the sintered body, are highly reactive, and when a molded body containing the α-sialon phosphor particles is subjected to the first firing, a sintered body can be obtained that absorbs light from an excitation light source having an emission peak wavelength in the range of 350 nm to 500 nm, for example, and emits light with efficiently converted wavelengths.

[0017] The α-sialon phosphor particles preferably have a composition represented by the following formula (I'). Ca k Si 12-(m+n) Al (m+n) O n N 16-n :Eu (I') (In formula (I'), k, m, and n satisfy the following conditions: 1.0≦k≦2.0, 2.0≦m≦6.0, and 0≦n≦1.0, respectively.)

[0018] When irradiated with light from an excitation light source having a peak emission wavelength in the range of 350 nm or more and 500 nm or less, the α-sialon phosphor particles preferably emit light having a peak emission wavelength in the range of 430 nm or more and 800 nm or less, more preferably emit light having a peak emission wavelength in the range of 500 nm or more and 700 nm or less, even more preferably emit light having a peak emission wavelength in the range of 550 nm or more and 650 nm or less, and even more preferably emit light having a peak emission wavelength in the range of 550 nm or more and 600 nm or less.

[0019] The α-sialon phosphor particles preferably have an average particle size (Fisher Sub-sieve sizer's number) of 2.0 μm or less as measured by a Fisher Sub-sieve sizer (FSSS) method. When the average particle size of the nitride phosphor measured by the FSSS method is 2.0 μm or less, a molded body with few voids can be formed. The average particle size of the α-sialon phosphor measured by the FSSS method may be less than 2.0 μm, 1.9 μm or less, or 1.8 μm or less. The average particle size of the α-sialon phosphor particles measured by the FSSS method may be 0.1 μm or more, 0.5 μm or more, or 1.0 μm or more. The FSSS method is a type of air permeation method, in which the specific surface area is measured using the air flow resistance to determine the particle size.

[0020] The α-sialon phosphor particles may be those produced as in the examples described below, or commercially available particles may be used.

[0021] The method for producing the sintered body includes forming a raw material mixture of α-sialon phosphor particles and yttrium oxide particles into a compact.

[0022] In preparing the green body, the yttrium oxide particles function as a sintering aid in the primary firing to obtain the first sintered body, as described below. When α-sialon phosphor particles react with each other in the high-density green body through the primary firing to grow crystals, it is believed that the yttrium oxide particles also react with the α-sialon phosphor particles, replacing some of the elements that make up the α-sialon phosphor particles with yttrium, thereby activating the reaction between the α-sialon phosphor particles. When α-sialon phosphor particles react with each other in the green body through the primary firing to grow crystals, it is believed that the replacement of some of the elements that make up the α-sialon phosphor particles with yttrium activates the reaction between the α-sialon phosphor particles, thereby affecting the rate of crystal growth and resulting in a first sintered body containing a dense α-sialon phosphor crystal phase with few voids.

[0023] In preparing the green body, the raw material mixture preferably contains 0.1 to 6.0 mass% of yttrium oxide particles, more preferably 0.1 to 5.5 mass%, and even more preferably 0.1 to 5.0 mass%, of the total of the α-sialon phosphor particles and yttrium oxide particles taken as 100 mass%. By including 0.1 to 6.0 mass% of yttrium oxide particles in the raw material mixture, when the total of the α-sialon phosphor particles and yttrium oxide particles is taken as 100 mass%, during primary firing to obtain a first sintered body, some of the elements constituting the α-sialon phosphor particles are replaced with yttrium, activating reactions between the α-sialon phosphor particles and affecting the rate of crystal growth. This allows for a first sintered body to be obtained that contains a dense α-sialon phosphor crystal phase with few voids and has a high relative density. Furthermore, a second sintered body with a high relative density can also be obtained by slicing the first sintered body into plates and subjecting it to secondary firing at a temperature in the range of 1600° C. to 1800° C. as described below. If the raw material mixture contains more than 6.0% by mass of yttrium oxide particles when the total of the α-sialon phosphor particles and yttrium oxide particles is taken as 100% by mass, it is estimated that a large amount of elements constituting the composition of the α-sialon phosphor particles will be replaced, resulting in the generation of large amounts of decomposition gas, and the resulting second sintered body may be deformed or have a low relative density. If the raw material mixture contains 0.1 mass% or less of yttrium oxide particles, or contains no yttrium oxide particles, when the total of the α-sialon phosphor particles and yttrium oxide particles is 100 mass%, there will be too few yttrium oxide particles reacting with the α-sialon phosphor particles, or the α-sialon phosphor particles and yttrium oxide particles will not react, which will have little effect on the rate of crystal growth between the α-sialon phosphor particles, and the relative density of the resulting first sintered body may be low.

[0024] The purity of the yttrium oxide particles is preferably 96% by mass or more, more preferably 97% by mass or more, even more preferably 98% by mass or more, and even more preferably 99% by mass or more. When the purity of the yttrium oxide particles is 96% by mass or more, in the primary firing to obtain a first sintered body, some of the elements constituting the composition of the α-sialon phosphor particles are substituted with yttrium, activating the reaction between the α-sialon phosphor particles and obtaining a first sintered body with a high relative density. The purity of yttrium oxide can also be determined by referring to the value listed in the catalog.

[0025] The yttrium oxide particles have a BET specific surface area of ​​3m 2 / g or more is preferable, and 5m 2 / g or more is more preferable, and 7m 2 / g or more is more preferable, and 10m 2 / g or more. The yttrium oxide particles preferably have a BET specific surface area of ​​20 m 2 / g or less, and 2 / g or less. 2 / g or more, and 20m 2 When the α-sialon phosphor particles and yttrium oxide particles are mixed uniformly, a raw material mixture containing the α-sialon phosphor particles and the yttrium oxide particles can be easily obtained, and a compact with high density can be obtained.

[0026] In preparing the compact, the remainder of the raw material mixture, excluding yttrium oxide particles, is preferably α-sialon phosphor particles. The raw material mixture preferably consists of α-sialon phosphor particles and yttrium oxide particles. The raw material mixture preferably contains α-sialon phosphor particles and yttrium oxide, but does not contain any other substances. The compact obtained by compacting the raw material mixture preferably consists of α-sialon phosphor particles, excluding yttrium oxide. The compact obtained by compacting the raw material mixture preferably consists of α-sialon phosphor particles and yttrium oxide particles. The compact obtained by compacting the raw material mixture preferably contains α-sialon phosphor particles and yttrium oxide particles, but does not contain any other substances. If the remainder of the raw material mixture, excluding yttrium oxide particles, is α-sialon phosphor particles, in obtaining a first sintered body by primary firing, the yttrium oxide particles act as a sintering aid, substituting yttrium for some of the elements constituting the composition of the α-sialon phosphor particles, thereby activating the reaction between the α-sialon phosphor particles, and obtaining a first sintered body with a high relative density. When the resulting first sintered body has a high relative density, it emits light with a high luminous flux when irradiated with excitation light. Even when the remainder of the raw material mixture, excluding yttrium oxide, is α-sialon phosphor particles and does not contain other oxides, such as aluminum oxide, a dense first sintered body with a high relative density can be obtained. When the raw material mixture contains an oxide other than yttrium oxide, such as aluminum oxide, the aluminum oxide may shrink during firing due to the heat of firing, resulting in a densified sintered body with a high relative density. When preparing a molded body, even when the remainder of the raw material mixture, excluding yttrium oxide particles, is α-sialon phosphor particles and the raw material mixture does not contain anything other than α-sialon phosphor particles and yttrium oxide particles, a dense first sintered body with a high relative density can be obtained by primary firing the molded body in a container containing pyrolytic boron nitride.

[0027] In preparing the green body, the raw material mixture preferably contains α-sialon phosphor particles in the range of 94% by mass to 99.9% by mass, more preferably 95% by mass to 99.8% by mass, even more preferably 96% by mass to 99.7% by mass, and even more preferably 97% by mass to 99.5% by mass, relative to 100% by mass of the total amount of the α-sialon phosphor particles and yttrium oxide particles. In preparing the green body, if the raw material mixture contains α-sialon phosphor particles in the range of 94% by mass to 99.9% by mass, relative to 100% by mass of the total amount of the α-sialon phosphor particles and yttrium oxide particles, light with a high luminous flux is emitted when irradiated with excitation light, and a dense first sintered body with a high relative density is obtained by primary firing. The raw material mixture may consist solely of α-sialon phosphor particles and yttrium oxide particles, or may contain, relative to 100% by mass of the raw material mixture, 94% to 99.9% by mass of α-sialon phosphor particles and 0.1% to 6% by mass of yttrium oxide particles. The raw material mixture may contain, relative to 100% by mass of the raw material mixture, 95% to 99.8% by mass of α-sialon phosphor particles and 0.2% to 5% by mass of yttrium oxide particles, 96% to 99.7% by mass of α-sialon phosphor particles and 0.3% to 4% by mass of yttrium oxide particles, or 97% to 99.5% by mass of α-sialon phosphor particles and 0.5% to 3% by mass of yttrium oxide particles.

[0028] In preparing the compact, the α-sialon phosphor particles and yttrium oxide particles can be mixed by dry mixing. Dry mixing may be performed using a mortar and pestle, or a mixer such as a ball mill with a medium. Dry mixing allows the α-sialon phosphor particles and yttrium oxide particles to be uniformly mixed and reduces particle aggregation. In preparing the compact, it is preferable not to add a molding aid to the raw material mixture. It is presumed that the raw material mixture is placed in a container containing pyrolytic boron nitride and subjected to primary firing, whereby components volatilized from the α-sialon phosphor particles are present in the container, increasing the internal pressure within the container and activating the reaction between the α-sialon phosphor particles. It is preferable that the compact obtained by molding the raw material mixture does not contain volatile components such as molding aids. When the raw material mixture contains a molding aid, the amount of the molding aid is preferably 10 parts by mass or less, more preferably 9 parts by mass or less, and even more preferably 8 parts by mass or less, and may be 0.1 parts by mass or more, based on 100 parts by mass of the raw material mixture. The molding aid is preferably a liquid other than water, such as methanol or ethanol.

[0029] In preparing a compact, the raw material mixture can be molded by known methods such as press molding and cold isostatic pressing (CIP). Examples of press molding methods include die press molding and CIP, the terminology of which is defined in JIS Z2500:2000, No. 2109. Uniaxial compression molding may also be used. To shape the raw material mixture, two methods may be used. For example, die press molding may be followed by CIP, or uniaxial compression by a roller bench method may be followed by CIP. CIP is preferably performed by pressing the compact using cold isostatic pressing, which uses water as a medium.

[0030] The pressure during die press molding or uniaxial compression molding is preferably in the range of 2 MPa to 50 MPa, more preferably 2 MPa to 30 MPa. If the pressure during die press molding or uniaxial compression molding is within the above-mentioned range, the molded body can be shaped into the desired shape. If the pressure during die press molding or uniaxial compression molding is greater than 50 MPa, molding cracks may occur if the particle size of the α-sialon phosphor particles contained in the raw material mixture is small.

[0031] The pressure in the CIP is preferably in the range of 50 MPa to 500 MPa, more preferably in the range of 50 MPa to 360 MPa. When the pressure in the CIP is in the range of 50 MPa to 360 MPa, a compact with high density can be obtained.

[0032] A method for producing a sintered body includes placing a compact in a container containing pyrolytic boron nitride.

[0033] When placing the green body in a container, the container in which the green body is placed preferably contains pyrolytic boron nitride. The container in which the green body is placed is preferably a pyrolytic boron nitride (PBN) crucible. The PBN crucible is preferably manufactured by a reduced pressure pyrolysis CVD (Chemical Vapor Deposition) method. PBN crucibles are preferred because they contain high purity boron nitride, are dense, have little outgassing even at high temperatures, and have excellent heat resistance and thermal conductivity. The size of the container need only be large enough to accommodate the green body. Because the container containing pyrolytic boron nitride is dense, the heat of the primary firing decomposes the α-sialon phosphor particles in the green body, generating gas that is less likely to be released outside the container and is more likely to be present around the green body. This promotes reactions between the α-sialon phosphor particles, making it easier to obtain a first sintered body with a high relative density.

[0034] When placing the molded body in the container, it is preferable to place the molded body so that at least one surface of the molded body is in contact with the bottom surface of the container. By placing the molded body so that at least one surface of the molded body is in contact with the bottom surface of the container, the molded body can be subjected to primary firing while stably placed in the container.

[0035] The method preferably includes placing a second lid containing pyrolytic boron nitride in the container so as to contact the molded body in the container. Placing the second lid containing pyrolytic boron nitride in the container so as to contact the molded body in the container makes it easier for the decomposition gas generated by the decomposition of the α-sialon phosphor particles in the molded body due to the heat of the primary firing to be present around the molded body in a higher concentration, thereby increasing the internal pressure around the molded body. This is thought to promote crystal growth among the α-sialon phosphor particles, making it easier to obtain a first sintered body with a high relative density. The second lid containing pyrolytic boron nitride is preferably a plate-shaped body having an area larger than the surface of the molded body that contacts the second lid. Placing the second lid in the container so as to contact the molded body, having an area larger than the surface of the molded body that contacts the container, makes it easier for the decomposition gas generated by the decomposition of the α-sialon phosphor particles in the molded body due to the heat of the primary firing to be present around the molded body. The second lid containing pyrolytic boron nitride may be of any size so long as it can be placed in the container. When the container in which the compact is placed is a cylindrical container with a bottom, it preferably has a diameter smaller than the inner diameter of the container. The second lid containing pyrolytic boron nitride may have the same thickness as the compact, or preferably has a thickness smaller than that of the compact. The second lid is preferably a second lid made of pyrolytic boron nitride (PBN), and is preferably a second lid made of PBN produced by a reduced pressure pyrolysis CVD method. A second lid made of PBN is preferred because the boron nitride is highly pure and dense, has little outgassing even at high temperatures, and has excellent heat resistance and thermal conductivity.

[0036] The method for producing the sintered body includes placing a first lid containing pyrolytic boron nitride on an opening of the container.

[0037] In disposing the first lid, by disposing the first lid containing pyrolytic boron nitride on the opening of the container in which the molded body is placed, decomposition gases generated by the decomposition of the α-sialon phosphor particles in the molded body due to the heat of the primary firing are not released to the outside of the container, creating a high internal pressure within the container, which acts on the crystal growth of the α-sialon phosphor particles, resulting in a first sintered body with a high relative density. The size of the first lid need only be large enough to close the opening of the container. The first lid is preferably made of pyrolytic boron nitride (PBN), and is preferably made of PBN produced by a reduced-pressure pyrolysis CVD method. PBN first lids are preferred because the boron nitride is highly pure and dense, has little outgassing even at high temperatures, and has excellent heat resistance and thermal conductivity.

[0038] Preferably, placing the first lid includes applying a load to the first lid. Applying a load to the first lid reduces the gap between the container and the first lid. By applying a load to the first lid to reduce the gap between the container and the first lid, decomposition gas from the α-sialon phosphor particles decomposed during the primary firing is less likely to be released to the outside of the container, the internal pressure within the container can be increased, and a first sintered body with a higher relative density can be obtained.

[0039] Applying a load to the first lid preferably includes placing a weight on the first lid. By placing the weight on the first lid, the gap between the opening of the container containing pyrolytic boron nitride and the first lid is further reduced, further reducing the release of decomposition gas from the α-sialon phosphor particles decomposed by the primary firing outside the container, further increasing the internal pressure within the container and resulting in a first sintered body with a higher relative density. The weight preferably contains at least one selected from the group consisting of tungsten, molybdenum, and tantalum. The weight is preferably made of a material that does not react with the boron nitride contained in the first lid, and is preferably a material that has a high true density and can withstand the temperature of the primary firing. When the weight is a metal containing at least one selected from the group consisting of tungsten, molybdenum, and tantalum, or an alloy containing two or more of these metals, placing the weight on the first lid reduces the gap between the container and the first lid without reacting with the boron nitride contained in the container.

[0040] The method for producing a sintered body includes subjecting a molded body in a container whose opening is blocked with a first lid to a primary firing at a temperature in the range of 1800°C or higher and 2000°C or lower to obtain a first sintered body containing an α-sialon phosphor crystal phase.

[0041] In obtaining the first sintered body, the molded body in a container whose opening is closed with a first lid is subjected to primary firing at a temperature in the range of 1800°C to 2000°C, whereby the α-sialon phosphor particles contained in the molded body react with each other and grow into crystals, and the decomposition gas produced by the decomposition of some of the α-sialon phosphor particles during the primary firing is not released to the outside of the container, increasing the internal pressure within the container and resulting in a first sintered body with a high relative density. Furthermore, in obtaining the first sintered body, the α-sialon phosphor particles and yttrium oxide particles contained in the molded body also react with each other, promoting the crystal growth of the α-sialon phosphor particles, and the decomposition gas of the α-sialon phosphor particles also increases the internal pressure within the container, resulting in a first sintered body with few voids and a high relative density.

[0042] In obtaining the first sintered body, the temperature of the primary firing is within the range of 1800° C. to 2000° C., preferably within the range of 1825° C. to 1975° C., and more preferably within the range of 1850° C. to 1950° C. If the temperature of the primary firing is within the range of 1800° C. to 2000° C., the reaction between the α-sialon phosphor particles contained in the compact and the reaction between the α-sialon phosphor particles and the yttrium oxide particles are promoted, and a first sintered body containing an α-sialon phosphor crystal phase and a subphase can be obtained.

[0043] Methods for performing the primary firing to obtain the first sintered body include an atmosphere sintering method in which firing is performed in a non-oxidizing atmosphere without applying pressure or load, and an atmosphere pressure sintering method in which firing is performed under pressure in a non-oxidizing atmosphere.

[0044] The method for obtaining the first sintered body preferably includes primary firing in a pressurized non-oxidizing atmosphere of 0.5 MPa to 200 MPa. Primary firing in a pressurized atmosphere of 0.5 MPa to 200 MPa reduces decomposition of the α-sialon phosphor particles contained in the compact, even when primary firing is performed at a high temperature of 1800°C to 2000°C. The decomposition gas generated by the decomposition of the α-sialon phosphor particles is not released from the container containing the pyrolytic boron nitride but remains within the container, increasing the internal pressure within the container, resulting in a first sintered body with a high relative density. Primary firing in a non-oxidizing atmosphere of 0.8 MPa to 150 MPa is more preferable, and primary firing in a non-oxidizing atmosphere of 1.0 MPa to 100 MPa is even more preferable. The pressure of the atmosphere during primary firing refers to gauge pressure.

[0045] In obtaining the first sintered body, the non-oxidizing atmosphere in which the primary firing is performed is preferably an atmosphere containing nitrogen gas. The non-oxidizing atmosphere in which the secondary firing described below is performed is also preferably an atmosphere containing nitrogen gas. The nitrogen gas-containing atmosphere in the primary and secondary firings is preferably an atmosphere containing at least 99% by volume of nitrogen. The nitrogen content in the nitrogen gas-containing atmosphere is preferably 99% by volume or more, more preferably 99.5% by volume or more. The nitrogen gas-containing atmosphere may contain trace amounts of gases such as oxygen in addition to nitrogen, but the oxygen content in the nitrogen gas-containing atmosphere is preferably 1% by volume or less, more preferably 0.5% by volume or less, even more preferably 0.1% by volume or less, even more preferably 0.01% by volume or less, and particularly preferably 0.001% by volume or less. The non-oxidizing atmosphere in which the primary and secondary firings are performed may be an atmosphere containing reducing nitrogen, or may be an atmosphere containing hydrogen gas and nitrogen. When hydrogen gas is contained in the nitrogen-containing atmosphere, the content of hydrogen gas in the atmosphere is preferably 1% by volume or more, more preferably 5% by volume or more, and even more preferably 10% by volume or more. The atmosphere for the heat treatment may be a reducing atmosphere using solid carbon in the air atmosphere.

[0046] The time for the primary firing to obtain the first sintered body may be appropriately selected depending on the atmospheric pressure, and is, for example, from 0.5 hours to 20 hours, and preferably from 1 hour to 10 hours.

[0047] The method for producing a sintered body preferably includes slicing a first sintered body into plate-like shapes, and subjecting the sliced ​​plate-like first sintered body to a second firing at a temperature of 1600°C or higher but lower than 1800°C to obtain a second sintered body containing an α-sialon phosphor crystal phase.

[0048] Fig. 2 is a flowchart showing an example of a method for manufacturing a sintered body. Similar to Fig. 1, the method for manufacturing a sintered body includes steps of: preparing α-sialon phosphor particles (S101); molding a raw material mixture of the α-sialon phosphor particles and yttrium oxide particles to prepare a molded body (S102); placing the molded body in a container containing pyrolytic boron nitride (S103); placing a first lid containing pyrolytic boron nitride on the opening of the container (S104); and performing primary firing at a temperature of 1800°C to 2000°C to obtain a first sintered body containing an α-sialon phosphor crystalline phase (S105). The method for manufacturing a sintered body preferably further includes slicing the first sintered body into plates (S106); and performing secondary firing at a temperature of 1600°C to 1800°C to obtain a second sintered body containing an α-sialon phosphor crystalline phase (S107).

[0049] The method for producing a sintered body preferably includes slicing the first sintered body into plates. The first sintered body may have a dull body color after primary firing. By performing secondary firing on the first sintered body sliced ​​into plates, the dull body color can be restored to its original color. The dull body color of the first sintered body means that the body color of the first sintered body differs from the body color of the α-sialon phosphor crystal phase. Furthermore, the restoration of the body color of the first sintered body to its original color means that the body color of the first sintered body returns to the original body color of the α-sialon phosphor crystal phase.

[0050] The slicing preferably includes slicing the first sintered body to a thickness of 2 mm or less. The first sintered body may have a dull body color due to the primary firing. The dull body color of the first sintered body refers to a blackish color that differs from the body color of the α-sialon phosphor crystal phase. By performing secondary firing on the first sintered body sliced ​​to a thickness of 2 mm or less, the dull body color inside the first sintered body can be restored to the original body color of the α-sialon phosphor, and the α-sialon phosphor crystal phase can be included. The slicing may include slicing the first sintered body to a thickness of 1.5 mm or less, or slicing to a thickness of 1 mm or less. In slicing, the first sintered body may be sliced ​​to a thickness of 0.1 mm or more, or 0.15 mm or more, taking into account the strength of the first sintered body.

[0051] In slicing, the first sintered body is preferably sliced ​​using blade dicing, laser dicing, or a wire saw, preferably using a wire saw, since the cut surface of the sliced ​​first sintered body becomes flat with high precision.

[0052] The method for producing a sintered body preferably includes secondarily firing the sliced ​​first sintered body at a temperature of 1600°C or higher but lower than 1800°C to obtain a second sintered body containing an α-sialon phosphor crystal phase. By secondarily firing the sliced ​​first sintered body at a temperature of 1600°C or higher but lower than 1800°C, it is possible to obtain a second sintered body in which the original color of the α-sialon phosphor crystal phase has been restored, even if the color of the first sintered body has become dull after the first firing. In obtaining the second sintered body, secondarily firing the sliced ​​first sintered body allows a second sintered body in which not only the surface but also the interior has been restored to the original color of the α-sialon phosphor crystal phase.

[0053] In obtaining the second sintered body, the temperature of the secondary firing is preferably lower than the temperature of the primary firing. The temperature of the secondary firing is preferably 1600°C or higher and lower than 1800°C, more preferably 1650°C or higher and 1790°C or lower, even more preferably 1660°C or higher and 1780°C or lower, and even more preferably 1670°C or higher and 1770°C or lower. When the temperature of the secondary firing of the sliced ​​first sintered body is 1600°C or higher and lower than 1800°C, impurities that are different in composition from the α-sialon phosphor crystal phase and the subphase contained in the first sintered body and that cause dullness are released as gas, and a second sintered body can be obtained in which the original body color of the α-sialon phosphor crystal phase is restored.

[0054] In obtaining the second sintered body, methods of performing the secondary firing include an atmosphere sintering method in which firing is performed in a non-oxidizing atmosphere without applying pressure or load, and an atmosphere pressure sintering method in which firing is performed under pressure in a non-oxidizing atmosphere. In obtaining the second sintered body, it is preferable to place the first sintered body in a firing furnace and perform the secondary firing. In obtaining the second sintered body, the first sintered body placed in a container can be placed in a firing furnace and subjected to the secondary firing.

[0055] The method for obtaining the second sintered body preferably includes placing the first sintered body in a container containing pyrolytic boron nitride and placing a first lid containing pyrolytic boron nitride on the opening of the container. By placing the first sintered body in a container containing pyrolytic boron nitride and placing the first lid containing pyrolytic boron nitride on the opening of the container, the α-sialon phosphor particles are decomposed by the heat of the secondary firing, and the gas produced is less likely to be released outside the container, and the gas is present around the compact, increasing the internal pressure of the container, and a second sintered body can be obtained in which the original body color of the α-sialon phosphor crystal phase is restored without reducing the relative density.

[0056] The process of obtaining the second sintered body preferably includes applying a load to the first lid. By applying a load to the first lid, the gap between the container and the first lid is reduced, the internal pressure in the container is increased, and a second sintered body having the original color of the α-sialon phosphor crystal phase can be obtained without reducing the relative density.

[0057] Obtaining the second sintered body preferably includes secondary firing in a pressurized non-oxidizing atmosphere of 0.5 MPa to 200 MPa. By performing secondary firing in a pressurized atmosphere of 0.5 MPa to 200 MPa, decomposition of the α-sialon phosphor particles contained in the first sintered body is reduced, and impurities having compositions other than the α-sialon phosphor crystal and subphase compositions are decomposed and released as gas, resulting in a second sintered body that is restored to the original body color of the α-sialon phosphor crystal phase. Obtaining the second sintered body more preferably involves secondary firing in a non-oxidizing atmosphere of 0.8 MPa to 150 MPa, and even more preferably in a non-oxidizing atmosphere of 1.0 MPa to 100 MPa. The pressure of the atmosphere during secondary firing refers to gauge pressure.

[0058] The non-oxidizing atmosphere in which the secondary firing is performed is preferably an atmosphere containing nitrogen gas. The non-oxidizing atmosphere in which the secondary firing is performed may be the same as or different from the atmosphere in which the primary firing is performed. The non-oxidizing atmosphere in the secondary firing refers to the same atmosphere as the non-oxidizing atmosphere in the primary firing.

[0059] In obtaining the second sintered body, the time for the secondary firing is preferably 1 hour or more and 5 hours or less. If the time for the secondary firing is 1 hour or more and 3 hours or less, decomposition of the crystal structure having the composition of the nitride phosphor contained in the first sintered body is reduced, and impurities such as crystals having a composition different from that of the nitride phosphor generated inside the first sintered body are easily decomposed and released as gas. The time for the secondary firing may be 1 hour or more and 2 hours or less.

[0060] The sintered body contains an α-sialon phosphor crystalline phase and has a relative density of 96% or more. In this specification, the sintered body includes a first sintered body and a second sintered body obtained by the above-mentioned method for producing a sintered body. The sintered body contains an α-sialon phosphor crystalline phase and has a relative density of 96% or more, and can emit light with a high luminous flux when irradiated with light. In order to emit light with a high luminous flux when irradiated with light, the relative density of the sintered body is preferably 97% or more, more preferably 98% or more. The relative density of the sintered body may be 100% or 99% or less. Even when the sintered body contains an α-sialon phosphor crystalline phase and a subphase, if the raw material mixture is assumed to consist only of α-sialon phosphor particles, the true density of the sintered body is the value obtained by multiplying 100% by mass of the raw material mixture by the true density of the α-sialon phosphor particles, and the relative density may exceed 100%.

[0061] The relative density of a sintered body is a value calculated from the apparent density of the sintered body relative to the true density of the sintered body. The relative density of a sintered body is calculated using the following formula (1). The sintered bodies shown in the following formulas (1) and (2) include a first sintered body and a second sintered body.

[0062]

number

[0063] If we assume that the raw material mixture consists of α-sialon phosphor particles, the true density of the sintered body is calculated by multiplying 100% by mass of the raw material mixture by the true density of the α-sialon phosphor particles.

[0064] The apparent density of a sintered body is the value obtained by dividing the mass of the sintered body by the volume of the sintered body determined by Archimedes' method, and is calculated by the following calculation formula (2): In the following calculation formula (2), the volume of the sintered body refers to the volume determined by Archimedes' method.

[0065]

number

[0066] When considering the true density of a sintered body, taking into account the subphase contained in the sintered body or the yttrium oxide particles contained in the raw material mixture, the true density of the sintered body is calculated by the following calculation formula (3).

[0067]

number

[0068] The volume of the α-sialon phosphor contained in the sintered body is calculated by the following formula (4).

[0069]

number

[0070] The volume of yttrium oxide contained in the sintered body is calculated by the following formula (5).

[0071]

number

[0072] The α-sialon phosphor crystalline phase contained in the sintered body preferably has a composition represented by the following formula (I): When the α-sialon phosphor crystalline phase contained in the sintered body has a composition represented by the following formula (I), the sintered body can emit light with a high relative luminous flux when irradiated with light, an emission peak wavelength in a desired wavelength range, and a desired color tone. (Ca 1-q Y q ) k Si 12-(m+n) Al (m+n) O n N 16-n :Eu (I) (In formula (I), k, m, n, and q satisfy the following relationships: 1.0≦k≦2.0, 2.0≦m≦6.0, 0≦n≦1.0, and 0.001≦q≦0.35, respectively.)

[0073] In the composition of the α-sialon phosphor crystalline phase represented by formula (I), the numerical values ​​represented by variables q and k represent the molar ratio of yttrium contained in 1 mole of the composition of the α-sialon phosphor crystalline phase. In the composition represented by formula (I), variable q may be in the range of 0.001 to 0.32 (0.001≦q≦0.32), 0.002 to 0.31 (0.002≦q≦0.31), or 0.003 to 0.30 (0.003≦q≦0.30).

[0074] The α-sialon phosphor crystal phase contained in the sintered body may have a composition represented by the following formula (I'): The composition represented by the following formula (I') is the same composition as the α-sialon phosphor particles contained in the raw material mixture. Ca k Si 12-(m+n) Al (m+n) O n N 16-n :Eu (I') (In formula (I'), k, m, and n satisfy the following conditions: 1.0≦k≦2.0, 2.0≦m≦6.0, and 0≦n≦1.0, respectively.)

[0075] The sintered body may contain an α-sialon phosphor crystal phase in which calcium contained in the composition of the α-sialon phosphor particles contained in the raw material mixture is not replaced with yttrium and the composition of the α-sialon phosphor particles remains the same.

[0076] The sintered body contains an α-sialon phosphor crystal phase and a subphase, and the subphase preferably contains a composition represented by the following formula (II). Ca2Si5N8(II)

[0077] The sintered body contains a subphase having a different composition from the α-sialon phosphor crystal phase, so that light irradiated onto the sintered body is scattered by the subphase, causing the α-sialon phosphor crystal phase to absorb the light and facilitate wavelength conversion, thereby enabling the sintered body to emit fluorescence with a high wavelength-converted luminous flux.

[0078] When the total volume of the α-sialon phosphor crystal phase and the subphase is taken as 100% by volume, the sintered body preferably contains 20% or less of the subphase, preferably 1% to 20% by volume, more preferably 2% to 18% by volume, and even more preferably 3% to 15% by volume. When the total volume of the α-sialon phosphor crystal phase and the subphase is taken as 100% by volume, the subphase content is 1% to 20% by volume. Even if the sintered body has a high relative density of 96% or more and does not contain voids, the incident light is scattered by the subphase, and the light is absorbed by the α-sialon phosphor crystal phase, thereby reducing color unevenness in the light emitted from the first sintered body. The content ratios of the α-sialon phosphor crystal phase and the subphase in the sintered body can be measured by quantitative analysis using an X-ray diffraction spectrum with an X-ray diffractometer (e.g., product name: Ultima IV, manufactured by Rigaku Corporation).

[0079] The sintered body can be used as a wavelength conversion member. The sintered body used as a wavelength conversion member preferably converts the wavelength of the irradiated light by irradiating it with light having an emission peak wavelength in the range of 380 nm to 570 nm, and emits light having a color tone within an area A defined by the chromaticity coordinates (x, y) of the CIE 1931 chromaticity diagram, where (x=0.549, y=0.425) is point 1A, (x=0.562, y=0.438) is point 2A, (x=0.589, y=0.411) is point 3A, and (x=0.576, y=0.407) is point 4A, and the lines connecting points 1A and 2A, 2A and 3A, 3A and 4A, and 4A and 1A.

[0080] 3 is a diagram showing area A in the xy chromaticity coordinates of the CIE 1931 chromaticity diagram. Light emitting a hue within area A on the chromaticity diagram exhibits an orange emission color.

[0081] A light emitting device is constructed by combining the sintered body obtained by the above-mentioned manufacturing method with a light emitting element such as an LED or LD as a wavelength conversion member. The light emitting device converts excitation light emitted from the light emitting element using the sintered body to emit light having a desired emission peak wavelength. The light emitting device emits mixed color light from the light from the light emitting element and light whose wavelength has been converted by the sintered body. The light emitting device may be used by combining the above-mentioned sintered body containing an α-sialon phosphor crystal phase with another sintered body containing a phosphor crystal phase other than the α-sialon phosphor crystal phase.

[0082] The light-emitting element preferably has an emission peak wavelength in the range of 350 nm to 500 nm, more preferably in the range of 360 nm to 480 nm, and even more preferably in the range of 380 nm to 460 nm. The light-emitting element may be, for example, a nitride-based semiconductor (In X Al Y Ga 1-X-Y It is preferable to use a semiconductor light-emitting element using a semiconductor light-emitting element (X, 0≦X, 0≦Y, X+Y≦1) as the excitation light source. By using a semiconductor light-emitting element as the excitation light source, it is possible to obtain a light-emitting device that is highly efficient, has high output linearity relative to input, and is stable and resistant to mechanical shocks.

[0083] 4A and 4B show an example of the configuration of a light-emitting device using a sintered body as a wavelength conversion member. FIG. 4A is a schematic plan view of the light-emitting device 100. FIG. 4B is a schematic cross-sectional view of the light-emitting device 100 taken along line IV-IV′ in FIG. 4A. The light-emitting device 100 includes a light-emitting element 10 having an emission peak wavelength in the range of 350 nm to 500 nm, and a wavelength conversion member 51 that emits light upon excitation by light from the light-emitting element 10. The light-emitting element 10 is flip-chip mounted on a substrate 11 via bumps made of a conductive member 61. The wavelength conversion member 51 is disposed on the light-emitting surface of the light-emitting element 10 via an adhesive layer 80. The light-emitting element 10 and the wavelength conversion member 51 have their sides covered with a light-reflective covering member 90. The light-emitting element 10 receives power from outside the light-emitting device 10 via wiring formed on the substrate 1 and the conductive member 61, causing the light-emitting device 10 to emit light. The light emitting device 100 may include a semiconductor element 12 such as a protective element for protecting the light emitting element 10 from being destroyed by application of an excessive voltage. The semiconductor element 12 may be mounted on the substrate 11 via a conductive member 61. A covering member 90 is disposed so as to cover the semiconductor element 12, for example. Each member used in the light emitting device will be described below. For details, the disclosure of JP 2014-112635 A can be referenced, for example.

[0084] The adhesive layer is preferably made of a material that can optically connect the light-emitting element and the wavelength conversion member. The material constituting the adhesive layer is preferably at least one resin selected from the group consisting of epoxy resin, silicone resin, phenolic resin, and polyimide resin. Alternatively, the light-emitting element and the wavelength conversion member may be directly bonded without an adhesive layer.

[0085] Examples of semiconductor elements that may be provided in a light-emitting device as needed include transistors for controlling light-emitting elements and protective elements for reducing damage to light-emitting elements and performance degradation due to excessive voltage application. Zener diodes are examples of protective elements. When a light-emitting device includes a covering member, it is preferable to use an insulating material for the covering member. More specifically, examples include phenolic resin, epoxy resin, bismaleimide triazine resin (BT resin), polyphthalamide (PPA) resin, and silicone resin. Colorants, phosphors, and fillers may be added to the covering member as needed. The light-emitting device may use bumps as conductive members. Examples of materials for the bumps include Au or its alloys, and other conductive materials include eutectic solder (Au-Sn), Pb-Sn, and lead-free solder.

[0086] An example of a method for manufacturing a light emitting device will be described. For details, refer to the disclosures of, for example, Japanese Patent Application Laid-Open No. 2014-112635 or Japanese Patent Application Laid-Open No. 2017-117912. The method for manufacturing a light emitting device preferably includes a step of arranging a light emitting element, a step of arranging a semiconductor element if necessary, a step of preparing a wavelength conversion member, a step of bonding the light emitting element and the wavelength conversion member, and a step of arranging a covering member.

[0087] For example, in the light-emitting element placement step, the light-emitting element is placed on a substrate. The light-emitting element and the semiconductor element are, for example, flip-chip mounted on the substrate. Furthermore, in the wavelength conversion member preparation step, a wavelength conversion member made of a ceramic sintered body obtained by the above-described manufacturing method is prepared. Next, in the bonding step between the light-emitting element and the wavelength conversion member, the prepared wavelength conversion member is placed opposite the light-emitting surface of the light-emitting element, and the wavelength conversion member is bonded to the light-emitting element with an adhesive layer. Next, in the covering member placement step, the side surfaces of the light-emitting element and the wavelength conversion member are covered with a covering member. This covering member is used to reflect light emitted from the light-emitting element. If the light-emitting device also includes a semiconductor element, it is preferable to position the semiconductor element so that it is embedded in the covering member. In this manner, the light-emitting device shown in Figures 4A and 4B can be manufactured. [Example]

[0088] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0089] Production of α-sialon phosphor particles 1 The raw materials used were Ca3N2, EuN, Si3N4, and AlN. Each compound was weighed in a glove box under an inert gas atmosphere so that the molar ratio of each element in the raw material mixture was 1.7:0.05:8.5:3.5 (Ca:Eu:Si:Al). The compounds were then mixed to obtain a phosphor raw material mixture. The molar ratio of each element in the raw material mixture was calculated by setting the combined molar ratio of Si and Al to 12. The resulting α-sialon phosphor raw material mixture was loaded into a PBN crucible and heat-treated at 1600°C under a gas pressure of 0.9 MPa (gauge pressure) for 5 hours in an atmosphere containing 99.9% or more nitrogen by volume and the remainder being oxygen (0.1% or less by volume). A fired product was obtained. The obtained fired product, in which particles were sintered, was dispersed and then sieved to remove coarse and fine particles, yielding α-sialon phosphor particles 1 having the composition represented by formula (I'). The obtained α-sialon phosphor particles 1 have the composition represented by formula (I'), in which k is 1.66, the sum of m and n (m+n) is 3.48, the molar ratio of Si is 8.52, and the molar ratio of Eu is 0.05. Elemental analysis of the composition of the α-sialon phosphor particles was performed by the method described below.

[0090] Production of α-sialon phosphor particles 2 α-sialon phosphor particles 2 were obtained in the same manner as α-sialon phosphor particles 1, except that the raw material compounds were weighed in a glove box under an inert gas atmosphere so that the molar ratio of each element was 1.7:0.05:8.5:3.5 (Ca:Eu:Si:Al), and the compounds were mixed to obtain a raw material mixture for the α-sialon phosphor. The obtained α-sialon phosphor particles 2 have the same values ​​as α-sialon phosphor particles 1 in the composition represented by formula (I') above for the sum of k, m, and n ("m+n" in formula (I')), the molar ratio of Si ("12-(m+n)" in formula (I')), and the molar ratio of Eu in the composition represented by formula (I').

[0091] Production of α-sialon phosphor particles 3 The raw material compounds were weighed in a glove box under an inert gas atmosphere so that the molar ratio of each element, Ca:Eu:Si:Al, was 1.74:0.01:8.5:3.5, and the compounds were mixed to obtain a raw material mixture for the α-sialon phosphor. Except for this, α-sialon phosphor particles 3 were obtained in the same manner as α-sialon phosphor particles 1. The obtained α-sialon phosphor particles 3 have a composition represented by formula (I') in which k is 1.69, the sum of m and n (m+n) is 3.49, the molar ratio of Si is 8.51, and the molar ratio of Eu is 0.01.

[0092] Production of α-sialon phosphor particles 4 Except for the fact that the raw material compounds were weighed in a glove box under an inert gas atmosphere so that the molar ratio of each element was 1.745:0.005:8.5:3.5 (Ca:Eu:Si:Al), and the compounds were mixed to obtain a raw material mixture for the α-sialon phosphor, α-sialon phosphor particles 4 were obtained in the same manner as α-sialon phosphor particles 1. The obtained α-sialon phosphor particles 2 have a composition represented by formula (I') in which k is 1.68, the sum of m and n (m+n) is 3.49, the molar ratio of Si is 8.51, and the molar ratio of Eu is 0.004.

[0093] The following analyses were carried out on each of the obtained α-sialon phosphor particles. The results of each analysis are shown in Table 1.

[0094] Average particle size The average particle size (Fisher sub-sieve sizer's number) of each α-sialon phosphor particle was measured by the Fisher Sub-Sieve Sizer (FSSS) method using a Fisher Sub-Sieve Sizer Model 95 (manufactured by Fisher Scientific).

[0095] Center particle size For each α-sialon phosphor particle, the central particle size (median diameter) at which the cumulative frequency from the small diameter side in the volumetric particle size distribution was 50% was measured using a laser diffraction particle size distribution analyzer (MASTER SIZER3000, manufactured by MALVERN).

[0096] Light-emitting properties Each α-sialon phosphor particle was irradiated with excitation light of 450 nm wavelength using a quantum efficiency measurement device (QE-2000, manufactured by Otsuka Electronics Co., Ltd.) to measure its emission spectrum at room temperature (25°C ± 5°C). From the emission spectrum of each α-sialon phosphor particle, the chromaticity coordinates (x, y) on the CIE (Commission Internationale de l'Eclairage) 1931 chromaticity diagram were determined. Furthermore, the wavelength at which the emission intensity was maximized in the emission spectrum of each α-sialon phosphor particle was determined as the emission peak wavelength (λp) (nm). Furthermore, the full width at half maximum (FWHM) of the emission peak in the emission spectrum of each α-sialon phosphor particle was determined. The FWHM (full width at half maximum) refers to the wavelength width of the emission spectrum that exhibits 50% of the maximum intensity of the emission peak intensity in the emission spectrum.

[0097] Reflectance spectrum Each α-sialon phosphor particle was measured using a spectrofluorometer (F-7100, Hitachi High-Tech Corporation) at room temperature (25°C ± 5°C) by irradiating each sample α-sialon phosphor particle with light from a halogen lamp (excitation light source). The wavelengths of the excitation and emission sides of the spectrofluorometer were adjusted to match and scan the wavelengths, and the reflectance spectrum was measured within the wavelength range of 380 nm to 730 nm. Using a standard reflector (Spectralon®, Labsphere), the reflectance of the α-sialon phosphor particle was calculated as a relative reflectance, relative to the reflectance of the standard reflector for excitation light with an excitation wavelength of 450 nm. The reflectance spectra of α-sialon phosphor particles 2 to 4 are shown in Figure 5.

[0098] Specific surface area by BET method The BET specific surface area of ​​each α-sialon phosphor particle was measured by the BET method using a fully automatic specific surface area measuring device (Macsorb, manufactured by Mountec Co., Ltd.).

[0099] [Table 1]

[0100] Each α-sialon phosphor particle has a BET specific surface area of ​​2.0 m 2 / g or more, and the average particle size measured by the FSSS method is 0.1 μm or more and less than 5 μm.

[0101] 5 shows the reflectance spectra of α-sialon phosphor particles 2 to 4. α-sialon phosphor particles 2 to 4 have a reflectance of 30% or more at a wavelength of 450 nm.

[0102] Example 1-1 Preparing α-sialon phosphor particles α-sialon phosphor particles 1 are prepared.

[0103] Preparing a compact A raw material mixture is obtained by mixing 1 part by mass of yttrium oxide particles with 100 parts by mass of α-sialon phosphor particles 1. The yttrium oxide particles have a purity of 99.9% by mass and a BET specific surface area of ​​14.4 m. 2 / g, and the average particle size measured by laser diffraction is 0.50 μm. The BET specific surface area of ​​the yttrium oxide particles was measured in the same manner as that of α-sialon phosphor particles 1. The average particle size of the yttrium oxide particles was determined by referring to the catalog value. In the table, yttrium oxide particles are represented as Y2O3 particles. The raw material mixture consists only of α-sialon phosphor particles 1 and yttrium oxide particles, and 100% by mass of the raw material mixture is the same as 100% by mass of the combined total of α-sialon phosphor particles 1 and yttrium oxide particles. The remainder of the raw material mixture, excluding the yttrium oxide particles, is α-sialon phosphor particles 1. The content of α-sialon phosphor particles 1 in 100% by mass of the raw material mixture is 99% by mass. The raw material mixture was filled into a mold and pressed at a pressure of 2 MPa to form a cylindrical compact with a diameter of 28.5 mm and a thickness of 9.3 mm. The compact was further subjected to CIP molding at a pressure of 352.8 MPa to form a cylindrical compact with a diameter of 26.2 mm and a thickness of 8.9 mm.

[0104] Placing the compact in a container The obtained compact was placed in a container containing pyrolytic boron nitride. A PBN crucible was used as the container containing pyrolytic boron nitride. The compact was placed so that the surface with the largest area was in contact with the bottom surface of the PBN crucible. In the compact, the first sintered compact, and the second sintered compact, the surface with the largest area is also referred to as the main surface. When the compact, the first sintered compact, and the second sintered compact are plate-shaped, they may have two opposing main surfaces.

[0105] Placing the first lid A first lid containing pyrolytic boron nitride was placed on the opening of the container in which the compact was placed. The first lid containing pyrolytic boron nitride was large enough to close the opening of the container. When placing the first lid, a weight was placed on the first lid to apply a load to the first lid. A metal tungsten weight was used as the weight. The load applied by the weight reduced the gap between the opening of the container and the first lid.

[0106] FIG. 6 is a cross-sectional view schematically illustrating a molded body 1 placed in a container 2 containing pyrolytic boron nitride. The molded body 1 is placed in the container 2 containing pyrolytic boron, and the opening 2a of the container 2 is closed by a first lid 3. A weight 4 is placed on the first lid 3, and the load of the weight 4 reduces the gap between the opening 2a of the container 2 and the first lid 3. The container 2 containing pyrolytic boron nitride and the first lid 3 containing pyrolytic boron nitride are dense, and the heat of the primary firing decomposes the α-sialon phosphor particles in the molded body 1, generating gas that surrounds the molded body 1, increasing the internal pressure within the container 2.

[0107] Obtaining the first sintered body The compact in the PBN crucible, whose opening was closed with a first lid loaded with a weight, was placed in a firing furnace (manufactured by Fuji Denpa Kogyo Co., Ltd.) The firing furnace was filled with a non-oxidizing atmosphere containing 99.9% by volume or more of nitrogen and the remainder being oxygen (0.1% by volume or less), and the compact in the PBN crucible was subjected to primary firing at 1850°C and 0.92 MPa for 5 hours, thereby obtaining a first sintered body containing an α-sialon phosphor crystal phase.

[0108] Slicing the first sintered body The obtained first sintered body was sliced ​​to a thickness of 380 μm using a wire saw.

[0109] Obtaining the second sintered body The sliced ​​first sintered body was placed in a PBN crucible, which is a container containing pyrolytic boron nitride. The sliced ​​first sintered body was placed so that its main surface was in contact with the bottom surface of the PBN crucible. A first lid containing pyrolytic boron nitride was placed at the opening of the container in which the first sintered body was placed so as to close the opening. A weight made of metallic tungsten was placed on the first lid. The load from the weight reduced the gap between the opening of the container and the first lid. The first sintered body in the PBN crucible, whose opening was closed with a first lid loaded with a weight, was placed in a firing furnace (manufactured by Fuji Radio Kogyo Co., Ltd.) The firing furnace was filled with a non-oxidizing atmosphere containing 99.9% by volume or more of nitrogen and the remainder being oxygen (0.1% by volume or less), and the first sintered body in the PBN crucible was subjected to secondary firing at 1700°C and 0.92 MPa for 1 hour, thereby obtaining a second sintered body containing an α-sialon phosphor crystal phase.

[0110] Example 1-2 After obtaining the first sintered body, the second sintered body was obtained in the same manner as in Example 1-1, except that the secondary firing temperature was set to 1725°C, and a second sintered body containing an α-sialon phosphor crystal phase was obtained.

[0111] Examples 1-3 After obtaining the first sintered body, the second sintered body was obtained in the same manner as in Example 1-1, except that the secondary firing temperature was set to 1675°C, and a second sintered body containing an α-sialon phosphor crystal phase was obtained.

[0112] Examples 1-4 After obtaining the first sintered body, the second sintered body was obtained in the same manner as in Example 1-1, except that the secondary firing temperature was set to 1750°C, and a second sintered body containing an α-sialon phosphor crystal phase was obtained.

[0113] The following measurements were carried out on the obtained first sintered body and second sintered body. The conditions and measurement results for each example are shown in Table 2. In Tables 2 to 5, the container containing pyrolytic boron nitride, the first lid containing pyrolytic boron nitride, and the second lid containing pyrolytic boron nitride described below are represented as PBN, and if the weight is metallic tungsten, it is represented as W. In addition, in Tables 2 to 5, the symbol "-" indicates that there is no corresponding item.

[0114] Relative density (%) The relative densities of the obtained first sintered body and second sintered body were calculated using the above-mentioned formulas (1) and (2). Since the content of α-sialon phosphor particles in the raw material mixture was 99 mass%, the content of yttrium oxide was not taken into consideration, and 100% was considered to be α-sialon phosphor particles, and the true density of the α-sialon phosphor particles was taken as the true density of the sintered body. The true density of the α-sialon phosphor particles was 3.2 g / cm 3 is.

[0115] Chromaticity coordinates (x, y) Each second sintered body was mounted on a light-emitting element (LED) with an emission peak wavelength of 455 nm to prepare a sample light-emitting device. In each sample light-emitting device, a current of 1 A was passed through the light-emitting element to irradiate each ceramic sintered body with excitation light, and the chromaticity coordinates (x, y) of the CIE 1931 color system of the fluorescence emitted from each ceramic sintered body were measured using a multichannel spectrometer (Hamamatsu Photonics K.K., product name: PMA-12).

[0116] [Table 2]

[0117] The first sintered body and the second sintered body of Examples 1-1 to 1-4 were placed in a container containing pyrolytic boron nitride, a first lid was placed on the opening of the container, and a weight was placed on the first lid to reduce the gap between the opening of the container and the first lid.The first or second firing was performed in a state where the α-sialon phosphor particles were decomposed by the heat of the first or second firing and gasified around the molded body or first sintered body in the container, and therefore the resulting first or second sintered body had a high relative density.

[0118] Furthermore, since the first sintered body and the second sintered body of Examples 1-1 to 1-4 contain yttrium oxide particles in the raw material mixture when preparing the molded body, when the first sintered body is obtained by primary firing, when the α-sialon phosphor particles react with each other and grow into crystals during the primary firing, the yttrium oxide particles also react with the α-sialon phosphor particles, replacing some of the elements that make up the composition of the α-sialon phosphor particles with yttrium, activating the reaction between the α-sialon phosphor particles and affecting the rate of crystal growth, resulting in the first sintered body and second sintered body containing a dense α-sialon phosphor crystal phase with few voids.

[0119] FIG. 7A is a photograph showing the appearance of the main surface of the first sintered body after slicing in Example 1-4, and FIG. 7B is a photograph showing the appearance of the main surface of the second sintered body in Example 1-4. The letters written on the surface of the first sintered body or the second sintered body in FIG. 7A or FIG. 7B are symbols for distinguishing sample numbers. As shown in FIG. 7A, the first sintered body obtained after the first firing had a dark and dull body color due to remaining impurities. As shown in FIG. 7B, by the second firing, the dark and dull color remaining on the surface of the first sintered body was decomposed and released as gas, and the obtained second sintered body had the body color (bright orange-yellow) of the α-sialon phosphor crystal phase.

[0120] FIG. 8 is a cross-sectional view schematically illustrating a compact 1 placed in a container 2 containing pyrolytic boron nitride. The compact 1 is placed in the container 2 containing pyrolytic boron, and the opening 2a of the container 2 is closed by a first lid 3. A weight 4 is placed on the first lid 3, and the load of the weight 4 reduces the gap between the opening 2a of the container 2 and the first lid 3. A second lid 5 containing pyrolytic boron nitride is placed in the container 2 so as to contact the compact 1 inside the container 2. By placing the second lid 5 inside the container 2 so as to contact the compact 1 inside the container 2, the decomposition gas generated by the decomposition of the α-sialon phosphor particles in the compact 1 due to the heat of the primary firing tends to be present in a higher concentration around the compact, thereby increasing the internal pressure around the compact 1 inside the container 2 and increasing the relative density of the resulting first sintered body.

[0121] Example 2 The second sintered body was obtained in the same manner as in Example 1-1, except that in preparing the α-sialon phosphor particles 2 and placing the molded body in the container, a second lid containing pyrolytic boron nitride was placed in the container so as to be in contact with the molded body in the container, and in obtaining the first sintered body, the primary firing temperature was set to 1875°C to obtain the first sintered body.

[0122] Example 3 A second sintered body was obtained in the same manner as in Example 1-1, except that in preparing the α-sialon phosphor particles 3 and placing the molded body in the container, a second lid containing pyrolytic boron nitride was placed in the container so as to be in contact with the molded body in the container.

[0123] Example 4 The second sintered body was obtained in the same manner as in Example 1-1, except that in preparing the α-sialon phosphor particles 3 and placing the molded body in the container, a second lid containing pyrolytic boron nitride was placed in the container so as to be in contact with the molded body in the container, and in obtaining the first sintered body, the primary firing temperature was set to 1875°C to obtain the first sintered body.

[0124] Example 5 The second sintered body was obtained in the same manner as in Example 1-1, except that in preparing the α-sialon phosphor particles 4 and placing the molded body in the container, a second lid containing pyrolytic boron nitride was placed in the container so as to be in contact with the molded body in the container, thereby obtaining the first sintered body.

[0125] Example 6 The second sintered body was obtained in the same manner as in Example 1-1, except that in preparing the α-sialon phosphor particles 4 and placing the molded body in the container, a second lid containing pyrolytic boron nitride was placed in the container so as to be in contact with the molded body in the container, and in obtaining the first sintered body, the primary firing temperature was set to 1875°C to obtain the first sintered body.

[0126] The obtained first sintered body and second sintered body were measured in the same manner as in Examples 1-1 to 1-4. Table 3 shows the conditions and measurement results for each example.

[0127] [Table 3]

[0128] The first sintered body and the second sintered body of Examples 2 to 6 were placed in a container containing pyrolytic boron nitride, and a second lid containing pyrolytic boron nitride was placed so that it was in contact with the molded body in the container.The first lid was then placed on the opening of the container, and a weight was applied to the first lid to reduce the gap between the opening of the container and the first lid.It is believed that the primary or secondary firing was carried out in a state where the decomposition gas, which was generated by the decomposition of the α-sialon phosphor particles due to the heat of the primary or secondary firing, was present in a higher concentration near the molded body or the first sintered body in the container, and therefore the internal pressure in the container was higher, and the resulting first or second sintered body had a higher relative density.

[0129] Furthermore, since the first and second sintered bodies of Examples 2 to 6 contain yttrium oxide particles in the raw material mixture when preparing the molded body, when the first sintered body is obtained by primary firing, when the α-sialon phosphor particles react with each other and grow into crystals during the primary firing, the yttrium oxide particles also react with the α-sialon phosphor particles, replacing some of the elements that make up the composition of the α-sialon phosphor particles with yttrium, activating the reaction between the α-sialon phosphor particles and affecting the rate of crystal growth, resulting in the first sintered body and second sintered body containing a dense α-sialon phosphor crystal phase with few voids.

[0130] α-sialon phosphor crystalline phase and subphase For the sintered body according to Example 2 and the sintered body according to Example 4, the content ratios of the α-sialon phosphor crystal phase and subphase are measured by the RIR (Reference Intensity Ratio) method in a powder X-ray diffraction (XRD) method using CuKα rays.

[0131] The sintered body according to Example 2 has a composition included in the composition represented by the formula (I), specifically, (Ca 0.704 Y 0.296 )2Si 9.134 Al 2.866 O 1.09 N 14.91 The content of the α-sialon phosphor crystal phase having a composition represented by: Eu is 100.0 mass %.

[0132] The sintered body according to Example 6 has a composition included in the composition represented by the formula (I), specifically, (Ca 0.704 Y 0.296 )2Si 9.134 Al 2.866 O 1.09 N 14.91 The content of the α-sialon phosphor crystal phase having a composition represented by: Eu is 87.2 mass %, and the content of the subphase having a composition represented by Ca2Si5N8, which is the composition represented by formula (II), is 12.8 mass %.

[0133] Comparative Example 1 The first sintered body was obtained in the same manner as in Example 1-1, except that in preparing the molded body, a molded body was prepared that did not contain yttrium oxide particles and was molded using only α-sialon phosphor particles as raw material; in placing the first lid, a first lid containing boron nitride (BN) was placed on the opening of the container; no weight was placed on the first lid, and no load was applied to the first lid; and in obtaining the first sintered body, the primary firing temperature was set to 1900°C.

[0134] Comparative Example 2 The first sintered body was obtained in the same manner as in Example 1-1, except that in preparing the molded body, a molded body was prepared that did not contain yttrium oxide particles and was molded using only α-sialon phosphor particles as raw materials, and in obtaining the first sintered body, the primary firing temperature was set to 1900°C.

[0135] Comparative Example 3 The first sintered body was obtained in the same manner as in Example 1-1, except that the temperature of the primary firing was set to 2000°C when placing the molded body in the container and when obtaining the first sintered body.

[0136] Comparative Example 4 The first sintered body was obtained in the same manner as in Example 1-1, except that in preparing the α-sialon phosphor particles, α-sialon phosphor particles 4 were prepared, and in placing the first lid, no weight was placed on the first lid and no load was applied to the first lid.

[0137] The obtained first sintered body was measured in the same manner as in Example 1-1. Table 4 shows the conditions and measurement results for each example.

[0138] [Table 4]

[0139] The first sintered body of Comparative Example 1 does not contain yttrium oxide particles in the raw material mixture, so the reaction between the α-sialon phosphor particles is not activated.In addition, since the first lid is a first lid containing boron nitride (BN) rather than pyrolytic boron nitride (PBN), the heat from the primary firing causes the α-sialon phosphor particles to decompose, resulting in the gasified decomposition gas being released outside the container, resulting in a low relative density of 68.4% for the resulting first sintered body.

[0140] In the first sintered body of Comparative Example 2, the raw material mixture does not contain yttrium oxide particles, so the reaction between the α-sialon phosphor particles is not activated, and the relative density of the obtained first sintered body is low at 83.5%.

[0141] For the first sintered body of Comparative Example 3, the primary firing temperature was set to 2000°C, but the raw material mixture did not contain yttrium oxide particles, and the reaction between the α-sialon phosphor particles was not sufficiently activated, resulting in a low relative density of 89.5% for the resulting first sintered body.

[0142] The first sintered body of Comparative Example 4 contained yttrium oxide particles in the raw material mixture and the container contained pyrolytic boron nitride (PBN). However, the high temperature of 1850°C during the primary firing caused the α-sialon phosphor particles to decompose, resulting in the gasified decomposition gas being released outside the container, resulting in the relative density of the resulting first sintered body being as low as 95.7%.

[0143] Example 7 An α-sialon phosphor 3 is prepared. As shown in Table 4, 0.1 parts by mass of yttrium oxide particles are mixed with 100 parts by mass of α-sialon phosphor particles 3 to obtain a raw material mixture. The content of yttrium oxide particles in 100% by mass of the raw material mixture is 0.1% by mass. The yttrium oxide particles have a purity of 99.9% by mass and a BET specific surface area of ​​14.4 m. 2 / g, and the average particle size measured by laser diffraction is 0.50 μm. The BET specific surface area of ​​the yttrium oxide particles was measured in the same manner as that used to measure the BET specific surface area of ​​α-sialon phosphor particles 1. The average particle size of the yttrium oxide particles was determined by referring to the catalog value. In the table, the yttrium oxide particles are referred to as Y2O3 particles. The α-sialon phosphor particles and yttrium oxide particles are mixed in a 500 mL ball mill using 15 to 20 alumina media with a diameter of 20 mm, and stirred at 1000 rpm for 15 hours.Furthermore, to prepare a raw material mixture, 7 parts by mass of ethanol is added as a molding aid to a total of 100 parts by mass of the α-sialon phosphor particles 3 and yttrium oxide particles, and the mixture is stirred at 1000 rpm for 0.5 hours (30 minutes). The raw material mixture contains α-sialon phosphor particles 3 and yttrium oxide particles, and 100% by mass of the raw material mixture is 100% by mass of the total of the α-sialon phosphor particles 3 and the yttrium oxide particles. The content of the yttrium oxide particles in 100% by mass of the raw material mixture is 0.1% by mass, and the content of the α-sialon phosphor particles 3 is 99.9% by mass. The raw material mixture was filled into a mold, and CIP molding was performed in the same manner as in Example 1-1 to form a cylindrical molded body with a diameter of 26.2 mm and a thickness of 8.9 mm.A first sintered body and a second sintered body were obtained in the same manner as in Example 1-1, except that the preparation of the molded body was performed as described above.

[0144] Example 8 The first sintered body and the second sintered body were obtained in the same manner as in Example 7, except that the content of yttrium oxide particles in 100 mass% of the raw material mixture was 1.0 mass% and the content of α-sialon phosphor particles was 99.0 mass%.

[0145] Example 9 The first sintered body and the second sintered body were obtained in the same manner as in Example 7, except that the content of yttrium oxide particles in 100% by mass of the raw material mixture was 3.0% by mass and the content of α-sialon phosphor particles was 97.0% by mass.

[0146] Example 10 The first sintered body and the second sintered body were obtained in the same manner as in Example 7, except that the content of yttrium oxide particles in 100% by mass of the raw material mixture was 5.0% by mass and the content of α-sialon phosphor particles was 95.0% by mass.

[0147] Example 11 The first sintered body and the second sintered body were obtained in the same manner as in Example 7, except that the content of yttrium oxide particles in 100 mass% of the raw material mixture was 6.0 mass% and the content of α-sialon phosphor particles was 94.0 mass%.

[0148] Relative density (%) The relative densities of the obtained first sintered body and second sintered body were calculated using the above-mentioned formulas (1) to (5). The true density of the α-sialon phosphor particles was 3.2 g / cm 3 The true density of yttrium oxide particles is 5.01 g / cm 3 The results are shown in Table 5.

[0149] [Table 5]

[0150] In the first and second sintered bodies according to Examples 7 to 11, when the total of the α-sialon phosphor particles and yttrium oxide particles contained in the raw material mixture was taken as 100% by mass, the yttrium oxide particles were in the range of 0.1% by mass to 6.0% by mass. The first sintered body had a relative density of 100%, and the second sintered body had a relative density of 96% or more, specifically 98% or more, resulting in high relative densities. In Examples 7 to 11, the compact or second sintered body was placed in a container containing pyrolytic boron nitride, a first lid was placed on the opening of the container, and a weight was applied to the first lid to reduce the gap between the opening of the container and the first lid. The primary or secondary firing was performed in a state in which the α-sialon phosphor particles were decomposed by the heat of the primary or secondary firing and gasified, and the resulting first or second sintered body had a high relative density.

[0151] Fig. 9 is a photograph showing the appearance of the first sintered body of Example 7. The body color of the first sintered body according to Example 7 was dark and dull. Fig. 10 is a photograph showing the appearance of the first sintered body obtained by slicing the first sintered body according to Example 7 shown in Fig. 9 into plates with a thickness of 380 µm. When the first sintered body was sliced ​​into plates with a thickness of 2 mm or less, the body color of the first sintered body in the center in the thickness direction was darker than that of the surface of the first sintered body.

[0152] Fig. 11 is a photograph showing the appearance of the main surface of the second sintered body of Example 7. The letters written on the surface of the second sintered body in Fig. 11 are symbols for distinguishing sample numbers. As shown in Figure 11, by the secondary firing, the blackening and dullness remaining on the surface of the first sintered body were decomposed and released as gas, and the resulting second sintered body had the body color (bright orange-yellow) of the α-sialon phosphor crystal phase.

[0153] Embodiments according to the present disclosure include the following method for producing a sintered body and the sintered body. [Section 1] providing α-sialon phosphor particles; preparing a green body by molding a raw material mixture obtained by mixing the α-sialon phosphor particles and yttrium oxide particles; placing the compact in a container containing pyrolytic boron nitride; placing a first lid comprising pyrolytic boron nitride over an opening of the container; and performing primary firing of the green body in the container, the opening of which is closed with the first lid, at a temperature in the range of 1800°C or more and 2000°C or less to obtain a first sintered body containing an α-sialon phosphor crystal phase. [Section 2] Slicing the first sintered body into plates; Item 1. A method for producing a sintered body according to Item 1, comprising: subjecting the sliced ​​plate-shaped first sintered body to secondary firing at a temperature of 1600°C or higher but lower than 1800°C to obtain a second sintered body containing an α-sialon phosphor crystal phase. [Section 3] Item 3. The method for producing a sintered body according to item 2, wherein obtaining the second sintered body comprises placing the first sintered body in a container containing pyrolytic boron nitride, and placing a first lid containing pyrolytic boron nitride on an opening of the container. [Section 4] Item 4. The method for producing a sintered body according to any one of items 1 to 3, wherein in preparing the molded body, the raw material mixture contains the yttrium oxide particles in a range of 0.1 mass% to 6.0 mass% when the total of the α-sialon phosphor particles and the yttrium oxide particles is 100 mass%. [Section 5] Item 4. The method for producing a sintered body according to Item 2 or 3, wherein the slicing comprises slicing the first sintered body to a thickness of 2 mm or less. [Section 6] Item 7. The method for producing a sintered body according to any one of items 1 to 6, further comprising: disposing a second lid containing pyrolytic boron nitride in the container so as to contact the molded body in the container, in disposing the molded body in the container. [Section 7] 7. The method for producing a sintered body according to claim 1, wherein the step of placing the first lid comprises applying a load to the first lid. [Section 8] Item 8. A method for producing a sintered body according to Item 7, wherein applying a load to the first lid comprises placing a weight on the first lid, and the weight comprises at least one selected from the group consisting of tungsten, molybdenum, and tantalum. [Section 9] In preparing the α-sialon phosphor particles, the α-sialon phosphor particles have a BET specific surface area of ​​2.0 m 2 Item 9. The method for producing a sintered body according to any one of items 1 to 8, wherein the sintered body has a reflectance of 30% or more at a wavelength of 450 nm and a surface roughness of 100% or more. [Section 10] Item 10. The method for producing a sintered body according to any one of items 1 to 9, wherein the first sintered body is obtained by performing the primary firing in a pressurized non-oxidizing atmosphere in the range of 0.5 MPa to 200 MPa. [Section 11] Item 11. The method for producing a sintered body according to any one of items 1 to 10, wherein in preparing the molded body, the remainder of the raw material mixture excluding the yttrium oxide particles is the α-sialon phosphor particles. [Section 12] Item 2 and any one of Items 3 to 11, which cite Item 2, include performing the secondary firing in a pressurized non-oxidizing atmosphere within a range of 0.5 MPa to 200 MPa in obtaining the second sintered body. [Section 13] A sintered body containing an α-sialon phosphor crystal phase and having a relative density of 96% or more. [Section 14] Item 14. The sintered body according to Item 13, wherein the α-sialon phosphor crystal phase has a composition represented by the following formula (I): (Ca 1-q Y q ) k Si 12-(m+n) Al (m+n) O n N 16-n :Eu (I) (In formula (I), k, m, n, and q satisfy the following relationships: 1.0≦k≦2.0, 2.0≦m≦6.0, 0≦n≦1.0, and 0.001≦q≦0.35, respectively.) [Section 15] Item 15. The sintered body according to item 13 or 14, comprising the α-sialon phosphor crystal phase and a subphase, wherein the subphase comprises a composition represented by the following formula (II): Ca2Si5N8(II) [Industrial Applicability]

[0154] The sintered body obtained by the manufacturing method of the present disclosure can be used as a wavelength conversion member capable of converting the wavelength of light emitted from an LED or LD in light-emitting devices used as light sources for in-vehicle use, general lighting, backlighting of liquid crystal display devices, illumination, projectors, etc. Furthermore, the ceramic sintered body obtained by the manufacturing method of the present disclosure emits light when irradiated with excitation light, and can be used as a material for solid scintillators. [Explanation of symbols]

[0155] 1: molded body, first sintered body or second sintered body, 2: container, 2a: opening of container, 3: first lid, 4: weight, 5: second lid, 10: light-emitting element, 11: substrate, 12: semiconductor element, 51: wavelength conversion member, 61: conductive member, 80: adhesive layer, 90: covering member, 100: light-emitting device.

Claims

1. providing α-sialon phosphor particles; preparing a green body by molding a raw material mixture obtained by mixing the α-sialon phosphor particles and yttrium oxide particles; placing the compact in a container containing pyrolytic boron nitride; placing a first lid comprising pyrolytic boron nitride over an opening of the container; performing primary firing on the molded body in the container, the opening of which is closed with the first lid, at a temperature in the range of 1800°C or higher and 2000°C or lower to obtain a first sintered body containing an α-sialon phosphor crystal phase.

2. Slicing the first sintered body into plates; 2. The method for producing a sintered body according to claim 1, further comprising: subjecting the sliced ​​plate-shaped first sintered body to a second firing at a temperature of 1600°C or higher and lower than 1800°C to obtain a second sintered body containing an α-sialon phosphor crystal phase.

3. 3. The method for producing a sintered body according to claim 2, wherein obtaining the second sintered body comprises placing the first sintered body in a container containing pyrolytic boron nitride, and placing a first lid containing pyrolytic boron nitride on an opening of the container.

4. 3. The method for producing a sintered body according to claim 1, wherein in preparing the molded body, the raw material mixture contains the yttrium oxide particles in a range of 0.1 mass % to 6.0 mass % when the total of the α-sialon phosphor particles and the yttrium oxide particles is 100 mass %.

5. The method for producing a sintered body according to claim 2 , wherein the slicing step includes slicing the first sintered body to a thickness of 2 mm or less.

6. 2. The method for producing a sintered body according to claim 1, wherein placing the compact in the container comprises placing a second lid containing pyrolytic boron nitride in the container so as to contact the compact in the container.

7. The method for producing a sintered body according to claim 1 or 3, wherein the step of placing the first lid comprises applying a load to the first lid.

8. 8. The method for producing a sintered body according to claim 7, wherein applying a load to the first lid comprises placing a weight on the first lid, the weight containing at least one selected from the group consisting of tungsten, molybdenum, and tantalum.

9. In preparing the α-sialon phosphor particles, the α-sialon phosphor particles have a BET specific surface area of ​​2.0 m ２ 2. The method for producing a sintered body according to claim 1, wherein the sintered body has a surface roughness of 1000 nm or more and a reflectance of 30% or more at a wavelength of 450 nm.

10. The method for producing a sintered body according to claim 1 , wherein obtaining the first sintered body comprises performing the primary firing in a pressurized non-oxidizing atmosphere within a range of 0.5 MPa to 200 MPa.

11. 2. The method for producing a sintered body according to claim 1, wherein in preparing the compact, the remainder of the raw material mixture other than the yttrium oxide particles is the α-sialon phosphor particles.

12. The method for producing a sintered body according to claim 2, wherein obtaining the second sintered body comprises performing the secondary firing in a pressurized non-oxidizing atmosphere within a range of 0.5 MPa to 200 MPa.

13. A sintered body containing an α-sialon phosphor crystal phase and having a relative density of 96% or more.

14. The sintered body according to claim 13, wherein the α-sialon phosphor crystal phase has a composition represented by the following formula (I): (Ca) １－ｑ Y ｑ ) ｋ Yes １２－（ｍ＋ｎ） Al （ｍ＋ｎ） O ｎ N １６－ｎ :Eu (I) (In formula (I), k, m, n, and q satisfy the following relationships: 1.0≦k≦2.0, 2.0≦m≦6.0, 0≦n≦1.0, and 0.001≦q≦0.35, respectively.)

15. 15. The sintered body according to claim 13, comprising the α-sialon phosphor crystal phase and a subphase, wherein the subphase has a composition represented by the following formula (II): . ２ 3) ５ ! ８ (=)

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