Wavelength conversion member, light-emitting device, and method for manufacturing a wavelength conversion member

Abstract

The present invention provides a wavelength conversion member, a light-emitting device, and a method for manufacturing the wavelength conversion member. [Solution] A wavelength conversion member comprising a sintered body containing a rare earth aluminate phosphor crystal phase, an alkaline earth metal aluminate crystal phase, and an aluminum oxide crystal phase; a light-emitting device equipped with this wavelength conversion member; and a method for manufacturing the aforementioned wavelength conversion member.

Description

[Technical Field]

[0001] This disclosure relates to a wavelength conversion member, a light-emitting device, and a method for manufacturing a wavelength conversion member. [Background technology]

[0002] Light-emitting devices are known that include light-emitting diodes (LEDs) or laser diodes (LDs) and wavelength conversion components containing phosphors that convert the wavelength of light emitted from the LEDs or LDs. Such light-emitting devices are used, for example, in automotive applications, general lighting, backlights for liquid crystal displays, and as light sources for projectors.

[0003] As a wavelength conversion member to be provided in a light-emitting device, for example, Patent Document 1 discloses a single-phase porous optoceramic having a density within a specific range relative to the theoretical density and being formed by sintering an oxide. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2017-197774 [Overview of the project] [Problems that the invention aims to solve]

[0005] When wavelength conversion components scatter light due to their porosity, a decrease in the density of the wavelength conversion component due to porosity tends to reduce the luminous flux, potentially lowering the light extraction efficiency of the wavelength conversion component. Furthermore, in the case of porous ceramics, the mechanical strength of the sintered body that forms the wavelength conversion component may be reduced due to the voids or pores contained within the ceramic. The purpose of this disclosure is to provide a wavelength conversion member, a light-emitting device, and a method for manufacturing a wavelength conversion member that can increase luminescence efficiency and mechanical strength. [Means for solving the problem]

[0006] The first embodiment is a wavelength conversion member comprising a sintered body containing a rare earth aluminate phosphor crystalline phase, an alkaline earth metal aluminate crystalline phase, and an aluminum oxide crystalline phase.

[0007] The second embodiment is a light-emitting device comprising the wavelength conversion member and a light-emitting element having an emission peak wavelength in the range of 365 nm to 500 nm and irradiating the wavelength conversion member.

[0008] A third aspect involves preparing alkaline earth metal aluminate particles and adding at least one rare earth element R selected from the group consisting of Y, La, Gd, Lu, and Tb to the alkaline earth metal aluminate particles. 1 The material comprises a first oxide particle containing a cerebrospinal fluid, a second oxide particle containing a cerebrospinal fluid, and a third oxide particle containing an algae, and optionally contains at least one element M selected from the group consisting of Ga and Sc. 1 A method for manufacturing a wavelength conversion member, comprising: preparing a raw material mixture which may contain quaternary oxide particles; molding the raw material mixture to obtain a molded body; and firing the molded body at a temperature range of 1600°C to 1800°C to obtain a sintered body containing a rare earth aluminate phosphor crystalline phase, an alkaline earth metal aluminate crystalline phase, and an aluminum oxide crystalline phase. [Effects of the Invention]

[0009] According to this disclosure, it is possible to provide a wavelength conversion member, a light-emitting device, and a method for manufacturing a wavelength conversion member that can increase luminescence efficiency and mechanical strength. [Brief explanation of the drawing]

[0010] [Figure 1] This is a flowchart showing the manufacturing method of a wavelength conversion component. [Figure 2] This is a flowchart showing the manufacturing method of a wavelength conversion component. [Figure 3] This is a schematic plan view of the light-emitting device. [Figure 4] This is a schematic cross-sectional view of the light-emitting device. [Figure 5]This graph shows the relationship between the relative density and fracture strength of the sintered body of the wavelength conversion member according to the example and the sintered body of the wavelength conversion member according to the comparative example. [Figure 6] This graph shows the relationship between the relative luminescence intensity and fracture strength of the sintered body of the wavelength conversion member according to the example and the sintered body of the wavelength conversion member according to the comparative example. [Figure 7] This graph shows the relationship between the transmittance of light at a wavelength of 550 nm and the fracture strength of the sintered body of the wavelength conversion member according to the example and the sintered body of the wavelength conversion member according to the comparative example. [Figure 8] This is an SEM image of the sintered body of the wavelength conversion member according to Example 1. [Figure 9] This is an SEM image of the sintered body of the wavelength conversion member according to Example 4. [Figure 10] This is an SEM image of the sintered body of the wavelength conversion member according to Comparative Example 1. [Figure 11] This is an SEM image of the sintered body of the wavelength conversion member according to Comparative Example 2. [Modes for carrying out the invention]

[0011] The following describes the wavelength conversion member, light-emitting device, and method for manufacturing the wavelength conversion member according to the present invention based on embodiments. However, the embodiments shown below are illustrative examples for realizing the technical concept of the present invention, and the present invention is not limited to the wavelength conversion member, light-emitting device, and method for manufacturing the wavelength conversion member described below. The relationship between color names and chromaticity coordinates, and the relationship between the wavelength range of light and the color names of monochromatic light, shall conform to JIS Z8110.

[0012] The wavelength conversion member comprises a sintered body containing a rare earth aluminate phosphor crystalline phase, an alkaline earth metal aluminate crystalline phase, and an aluminum oxide crystalline phase.

[0013] The wavelength conversion member comprises a sintered body containing a rare earth aluminate phosphor crystal phase, an alkaline earth metal aluminate crystal phase, and an aluminum oxide crystal phase. The alkaline earth metal aluminate crystal phase scatters light incident on the sintered body, including light incident on the sintered body from an oblique direction, for example. This allows for efficient wavelength conversion by the rare earth aluminate phosphor crystal phase, thereby increasing the luminescence efficiency (luminescence efficiency specifically refers to luminescence intensity) of the wavelength conversion member. The alkaline earth metal aluminate crystal phase contained in the sintered body can scatter incident light without hindering the light absorption of the rare earth aluminate phosphor crystal phase or the emission of light whose wavelength has been converted by the rare earth aluminate phosphor crystal phase. Because the alkaline earth metal aluminate crystal phase scatters light incident on the sintered body, the mechanical strength of the sintered body can be increased compared to cases where incident light is scattered by voids or pores.

[0014] In a sintered body provided in a wavelength conversion member, it is preferable that the alkaline earth metal aluminate crystal phase is within the range of 0.1% to 10.0% when the total of the rare earth aluminate phosphor crystal phase, alkaline earth metal aluminate crystal phase, and aluminum oxide crystal phase is set to 100% by volume. If the alkaline earth metal aluminate crystal phase is within the range of 0.1% to 10.0% when the total of the rare earth aluminate phosphor crystal phase, alkaline earth metal aluminate crystal phase, and aluminum oxide crystal phase is set to 100% by volume, the light incident on the sintered body can be scattered without hindering the light absorption and emission of the rare earth aluminate phosphor crystal phase, thereby increasing the luminescence efficiency. In a sintered body provided in a wavelength conversion member, when the total of the rare earth aluminate phosphor crystal phase, the alkaline earth metal aluminate crystal phase, and the aluminum oxide crystal phase is taken as 100 volume%, the alkaline earth metal aluminate crystal phase is more preferably in the range of 0.3 volume% to 9 volume%, even more preferably in the range of 0.5 volume% to 8 volume%, and may also be in the range of 1.0 volume% to 8.0 volume%. In a sintered body, the volume ratio of the alkaline earth metal aluminate crystal phase to the total of the rare earth aluminate phosphor crystal phase, the alkaline earth metal aluminate crystal phase, and the aluminum oxide crystal phase (100 volume%) can be calculated by determining the area ratio of the alkaline earth metal aluminate crystal phase to 100 area% of the surface or cross-section of the sintered body in an SEM image measured using a scanning electron microscope (SEM), and converting the area ratio to a volume ratio (volume%). The alkaline earth metal aluminate crystalline phase in the sintered body is presumed to exist in the thickness direction as well as on the surface or cross-section of the sintered body. The measurement range of the sintered body for measuring the area ratio of the crystalline phase is 1257 μm in the SEM image measured using a scanning electron microscope (SEM). 2 It is preferable that this be the case.

[0015] The rare earth aluminate phosphor crystal phase preferably contains at least one element selected from the group consisting of Y, La, Lu, Gd, and Tb. When the rare earth aluminate phosphor crystal is a rare earth aluminate phosphor crystal phase containing at least one element selected from the group consisting of Y, La, Lu, Gd, and Tb, it is easy to obtain a rare earth aluminate phosphor crystal phase having a composition that absorbs the incident excitation light and converts the wavelength into light of a desired color tone. In addition, when a sintered body contains an alkaline earth metal aluminate crystal phase containing at least one element selected from the group consisting of Y, La, Lu, Gd, and Tb, the rare earth aluminate phosphor crystal phase can scatter the light incident on the sintered body by the alkaline earth metal aluminate crystal phase without inhibiting the absorption and emission of light, and can increase the light emission efficiency of the wavelength conversion member provided with the sintered body. The element contained in the rare earth aluminate phosphor crystal phase may be at least one selected from the group consisting of Y, La, Lu, and Gd, may be at least one selected from the group consisting of Y, La, and Lu, or may be at least one selected from the group consisting of Y and Lu.

[0016] The rare earth aluminate phosphor crystal phase preferably has a composition represented by the following formula (I). (R 1 1-n Ce n )3(Al 1-m M 1 m ) 5k O 12 (I) (In the formula (I), R 1 is at least one element selected from the group consisting of Y, La, Lu, Gd, and Tb, M 1 is at least one element selected from the group consisting of Ga and Sc, and n, m, and k satisfy 0.002 ≦ n ≦ 0.02, 0 ≦ m ≦ 0.4, and 0.95 ≦ k ≦ 1.10, respectively.)

[0017] In the composition represented by the formula (I), R 1The composition may contain two or more rare earth elements. Ce is the activating element of the rare earth aluminate phosphor crystalline phase, and the product of the variable n and 3 represents the molar ratio of Ce in the composition represented by formula (I). The variable n is more preferably 0.002 to 0.016 (0.002 ≤ n ≤ 0.016), and even more preferably 0.003 to 0.015 (0.003 ≤ n ≤ 0.015). In the composition represented by formula (I), the product of the variable m, 5 and k represents element M 1 This represents the molar ratio of element M. 1 The element is not included in the composition represented by formula (I), that is, m = 0. In the composition represented by formula (I), in order to convert wavelengths to the desired color tone, the variable m may be between 0.00001 and 0.02 (0.00001 ≤ m ≤ 0.02), or between 0.00005 and 0.018 (0.00005 ≤ m ≤ 0.018). In the composition represented by formula (I), the product of the variable k and 5 is Al and element M 1 This represents the total molar ratio. The variable k is more preferably between 0.96 and 1.09 (0.96 ≤ k ≤ 1.09), and even more preferably between 0.97 and 1.08 (0.97 ≤ k ≤ 1.08).

[0018] The alkaline earth metal aluminate crystalline phase preferably contains at least one element selected from the group consisting of Ba, Sr, and Ca. When the alkaline earth metal aluminate crystalline phase contains at least one element selected from the group consisting of Ba, Sr, and Ca, it is possible to efficiently scatter the light incident on the sintered body without hindering the light absorption and emission of the rare earth aluminate phosphor crystalline phase, thereby increasing the luminescence efficiency. The alkaline earth metal aluminate crystalline phase contains at least one element selected from the group consisting of Ba, Sr, and Ca, and may contain two or more elements selected from the group consisting of Ba, Sr, and Ca. The alkaline earth metal aluminate particles do not react easily with the compounds constituting the rare earth aluminate phosphor crystalline phase, the rare earth aluminate phosphor crystalline phase does not decompose during firing, and the light incident on the sintered body of the wavelength conversion member can be scattered without hindering the light absorption and emission of the formed rare earth aluminate phosphor crystalline phase.

[0019] Alkaline earth metal aluminate crystalline phases include (Ca,Sr,Ba)Al2O4 and (Ca,Sr,Ba)4Al 14 O 25 (Ca,Sr,Ba)Al 12 O 19 (Ca,Sr,Ba)Mg2Al 16 O 27 , and (Ca,Sr,Ba)MgAl 10 O 17 It is preferable to have at least one composition selected from the group consisting of the above. The refractive index of the alkaline earth metal aluminate contained in the alkaline earth metal aluminate crystal phase is preferably lower than that of the rare earth aluminate phosphor crystal phase in order to efficiently scatter the light incident on the sintered body. The refractive index of the rare earth aluminate phosphor crystal phase having the composition represented by formula (I) is in the range of 1.8 to 1.9. For example, the composition represented by formula (I) includes, for example, (Y 1-0.005 Ce 0.005 )3Al 5.1 O 12The refractive index of the rare earth aluminate phosphor crystalline phase represented by is 1.83. The refractive index of the alkaline earth metal aluminate crystalline phase represented by BaAl2O4 is 1.68. When the alkaline earth metal aluminate crystalline phase contains a crystalline phase having the above-mentioned composition, it is possible to scatter the light incident on the sintered body of the wavelength conversion member without hindering the light absorption or emission of the rare earth aluminate phosphor crystalline phase, thereby increasing the luminescence efficiency. Furthermore, when the alkaline earth metal aluminate crystalline phase contains a crystalline phase having the above-mentioned composition, the strength of the sintered body can be improved compared to the case where light is scattered by voids. In this specification, in the composition formula representing a compound, multiple elements separated by commas (,) mean that at least one of these multiple elements is contained in the composition of the compound. Multiple elements separated by commas (,) in the composition formula representing a compound include at least one element selected from the multiple elements separated by commas (,) in the composition formula, and may include two or more elements in combination from the multiple elements.

[0020] The sintered body provided in the wavelength conversion member preferably has a relative density of 90% or more, more preferably 92% or more, even more preferably 93% or more, and particularly preferably 94% or more. The sintered body provided in the wavelength conversion member may have a relative density of 100%, 99.8% or less, or 99.5% or less. When the relative density of the sintered body is within the range of 90% to 100%, the alkaline earth metal aluminate crystal phase scatters the light incident on the sintered body, and the rare earth aluminate phosphor crystal phase efficiently converts the wavelength, resulting in emission with high luminescence efficiency. Even if the relative density of the sintered body is less than 100% and contains voids, the alkaline earth metal aluminate crystal phase also functions as a binder, bonding the rare earth aluminate phosphor crystal phase, thereby increasing the strength of the sintered body.

[0021] The relative density of a sintered body can be calculated by dividing the apparent density of the sintered body by the true density of the sintered body. The relative density of a sintered body can be calculated using the following formula (1).

[0022]

number

[0023] The apparent density of a sintered body can be calculated by dividing the mass of the sintered body by its volume. The apparent density of a sintered body can be calculated using the following formula (2).

[0024]

number

[0025] The true density of the sintered body can be calculated from the rare earth aluminate phosphor crystalline phase, alkaline earth metal aluminate crystalline phase, and aluminum oxide phase contained in the sintered body. The true density of the sintered body can be calculated using the following formula (3).

[0026]

number

[0027] The porosity of a sintered body is the remainder obtained by subtracting the relative density of the sintered body from 100%. In a sintered body containing a rare earth aluminate phosphor crystalline phase, an alkaline earth metal aluminate crystalline phase, and an aluminum oxide crystalline phase, even if the relative density is lower than that of a sintered body that does not contain the alkaline earth metal aluminate crystalline phase, the alkaline earth metal aluminate crystalline phase acts as a binder, and the presence of the alkaline earth metal aluminate crystalline phase can increase the strength.

[0028] The sintered body is preferably a plate-like body having one surface and another surface opposite to this surface. When the sintered body is a plate-like body, the sintered body may be a sintered body provided in a transmissive wavelength conversion member in which the incident surface on which light is incident and the exit surface on which the wavelength-converted light is emitted are different. The sintered body may also be a sintered body provided in a reflective wavelength conversion member in which the incident surface on which light is incident and the exit surface on which the wavelength-converted light is emitted are the same surface.

[0029] The thickness of the sintered body is preferably in the range of 50 μm to 250 μm, but may also be 80 μm or more, 100 μm or more, or 240 μm or less. When the thickness of the sintered body is in the range of 50 μm to 250 μm, it is possible to obtain light emission with high luminescence characteristics by irradiation with light while maintaining the strength of the sintered body.

[0030] When the wavelength conversion member is a plate-shaped sintered body, it is preferable that at least one surface of the sintered body—one surface and the other surface facing the first surface—is provided with an optical thin film that reflects a first light having an emission peak wavelength in the range of 365 nm to 500 nm, absorbs the first light, and transmits a second light emitted by a rare-earth aluminate phosphor crystal phase.

[0031] The optical thin film preferably has an average reflectance of 80% or more for light in the range of 365 nm to 500 nm. If the average reflectance of the optical thin film for light in the range of 365 nm to 500 nm is 80% or more, the optical thin film can reflect first light having an emission peak wavelength in the range of 365 nm to 500 nm. The optical thin film transmits second light emitted by the rare earth aluminate phosphor crystal phase, and it is preferable that the transmittance of light with a wavelength of 550 nm, for example, is 80% or more. The average reflectance and transmittance of an optical thin film can be measured by irradiating the optical thin film with light from a light-emitting element from the normal direction (incident angle 0 degrees) and using a spectroscopic ellipsometer (e.g., VASE Spectroscopic Ellipsometer, JAWoollam).

[0032] The wavelength conversion member, by comprising an optical thin film, reflects first light having an emission peak wavelength in the range of 365 nm to 500 nm irradiated onto the sintered body. The reflected first light is absorbed and effectively utilized by the rare-earth aluminate phosphor crystal phase contained in the sintered body, and second light, whose wavelength has been converted by the rare-earth aluminate phosphor crystal phase, is emitted from the optical thin film. The optical thin film may be a single film made of a single material, or it may be a dielectric multilayer film in which a first dielectric layer and a second dielectric layer with different refractive indices are alternately stacked. The optical thin film reduces the reflectivity of the light incident on the sintered body, allowing sufficient excitation light to be incident, and reduces the refractive index difference between air and the sintered body, thereby enabling the emission of highly luminous light from the sintered body. When the optical thin film is a single film, examples include a single film made of magnesium fluoride or a single film made of silicon dioxide. When the optical thin film is a single film, the thickness of the optical thin film is preferably in the range of 80 nm to 130 nm. The refractive index of the optical thin film is preferably lower than that of the rare-earth aluminate phosphor crystalline phase and the alkaline-earth metal aluminate crystalline phase contained in the sintered body. The wavelength conversion member is preferably provided with an optical thin film on the light-emitting side of the sintered body.

[0033] The optical thin film is preferably a dielectric multilayer film. The dielectric multilayer film is formed by stacking a first dielectric layer and a second dielectric layer having a different refractive index from the first dielectric layer. The dielectric multilayer film consists of a first dielectric layer made of a first dielectric material with a low refractive index and a second dielectric layer made of a second dielectric material with a higher refractive index than the first dielectric material. The refractive index of each layer, the difference in refractive index between the two layers, and the number of alternating periods are appropriately set so that a desired reflectivity can be stably obtained in a desired wavelength range.

[0034] The refractive index of the first dielectric layer with a low refractive index (first refractive index) can be set, for example, within the range of 1.0 to 1.8, preferably within the range of 1.2 to 1.6. The first dielectric layer can be formed from, for example, SiO2 (refractive index of, for example, 1.5). The refractive index of the second dielectric layer with a high refractive index (second refractive index) can be set, for example, within the range of 1.5 to 3.0, preferably within the range of 2.0 to 2.6. The second dielectric layer can be formed from, for example, Nb2O5 (refractive index of, for example, 2.4). The number of periods in which the first dielectric layer and the second dielectric layer are alternately formed can be set, for example, within the range of 1 to 30, preferably within the range of 1 to 25.

[0035] The wavelength conversion member may have a light-transmitting member on the surface of the sintered body. If the wavelength conversion member has an optical thin film on the light-emitting side of the sintered body, the light-transmitting member may also be provided on the light-emitting side of the optical thin film. By providing a light-transmitting member, the wavelength conversion member can protect the sintered body, or the sintered body and the optical thin film, from the external environment. The material forming the light-transmitting member is at least one selected from the group consisting of resins and light-transmitting inorganic materials. Preferably, the light-transmitting member has a transmittance of 80% or more for light with a wavelength of 550 nm, for example. The light-transmitting member may be configured in a flat plate shape and have a bottom surface, a top surface, and side surfaces. As the resin, for example, it can be selected from silicone resin or epoxy resin. As the light-transmitting inorganic material, for example, glass materials selected from borosilicate glass or quartz glass, or sapphire, BaF2, CaF2.

[0036] The sintered body provided in the wavelength conversion member preferably has a fracture strength exceeding 4.0 N, as measured under the following conditions. Even when the relative density of the sintered body is between 90% and 99.5%, it is preferable that the fracture strength exceeds 4.0 N and the mechanical strength is maintained. Measurement conditions for fracture strength The test method used is a three-point bending test, with a support distance of 10 mm, using a rectangular prism test specimen measuring 2 mm in width, 0.3 mm in height, and 11 mm in length, and a head speed of 1.0 mm / min.

[0037] The method for manufacturing the wavelength conversion member involves preparing alkaline earth metal aluminate particles and combining the alkaline earth metal aluminate particles with at least one rare earth element R selected from the group consisting of Y, La, Gd, Lu, and Tb. 1 The material comprises a first oxide particle containing a cerebrospinal fluid, a second oxide particle containing a cerebrospinal fluid, and a third oxide particle containing an algae, and optionally contains at least one element M selected from the group consisting of Ga and Sc. 1 The process includes: preparing a raw material mixture which may contain quaternary oxide particles; molding the raw material mixture to obtain a molded body; and firing the molded body at a temperature range of 1600°C to 1800°C to obtain a sintered body containing a rare earth aluminate phosphor crystalline phase, an alkaline earth metal aluminate crystalline phase, and an aluminum oxide crystalline phase.

[0038] Figure 1 is a flowchart illustrating the method for manufacturing a wavelength conversion member. The method for manufacturing a wavelength conversion member will be explained with reference to Figure 1. The method includes preparing alkaline earth metal aluminate particles (S101), preparing a raw material mixture (S102), molding the raw material mixture to obtain a molded body (S103), and firing the molded body to obtain a sintered body (S104).

[0039] In preparing alkaline earth metal aluminate particles, compounds containing each element that will serve as the raw material for the alkaline earth metal aluminate particles are prepared to obtain alkaline earth metal aluminate particles of a desired composition. After mixing the raw material compounds, the mixture is heat-treated to obtain alkaline earth metal aluminate particles. Commercially available alkaline earth metal aluminate particles may also be used.

[0040] Compounds used as raw materials for alkaline earth metal aluminate particles include, for example, oxides, hydroxides, chlorides, carbonates, etc., that contain each of the elements constituting the alkaline earth metal aluminate particles. Examples of raw material compounds containing alkaline earth metal elements include Ba(OH)2, BaO, BaCl2, BaCO3, Al2O3, Al(OH)3, AlCl3, Al2(CO3)3, Ca(OH)2, CaO, CaCl2, CaCO3, Sr(OH)2, SrO, SrCl2, SrCO3, etc. In order to obtain an alkaline earth metal aluminate crystal phase having a lower refractive index than the rare earth aluminate phosphor crystal phase in the resulting sintered body without hindering the light absorption and emission of the rare earth aluminate phosphor crystal phase, it is preferable that the raw material is a carbonate or oxide containing an alkaline earth metal element.

[0041] The compounds used as raw materials for alkaline earth metal aluminate particles are mixed to obtain alkaline earth metal aluminate particles of the desired composition, and then heat-treated at a temperature of 1400°C to 1600°C to obtain alkaline earth metal aluminate particles. The heat treatment may be carried out in an atmosphere of air (oxygen content of 20% by volume or more). The pressure of the heat treatment may be atmospheric pressure (101.325 kPa).

[0042] The resulting heat-treated material may be wet-crushed to obtain alkaline earth metal aluminate particles, or dried and pulverized to obtain alkaline earth metal aluminate particles. Alternatively, both wet-crushing and dry-pulverization may be performed to obtain alkaline earth metal aluminate particles. The resulting heat-treated material can be dispersed in a liquid and wet-crushed, for example, using a ball mill. Alternatively, the resulting heat-treated material may be dried at a temperature of, for example, 50°C to 150°C and then pulverized using a ball mill.

[0043] The alkaline earth metal aluminate particles to be prepared are (Ca,Sr,Ba)Al2O4 and (Ca,Sr,Ba)4Al 14 O 25 (Ca,Sr,Ba)Al 12 O 19 (Ca,Sr,Ba)Mg2Al16 O 27 , and (Ca,Sr,Ba)MgAl 10 O 17 It is preferable to have at least one composition selected from the group consisting of the above. When alkaline earth metal aluminate particles have the above composition and contain alkaline earth metal aluminate particles, the light incident on the sintered body of the wavelength conversion member can be scattered in the sintered body without hindering the absorption or emission of light of the rare earth aluminate phosphor crystal phase, thereby increasing the luminescence efficiency, and the alkaline earth metal aluminate crystal phase acts as a binder, thereby increasing the strength of the sintered body.

[0044] The alkaline earth metal aluminate particles to be prepared have a specific surface area of ​​0.1 m² as measured by the BET method. 2 / g or more 2.0m 2 It is preferable that the range be less than or equal to / g, and 0.3m 2 / g or more 1.0m 2 It is even more preferable that the amount is within the range of / g or less. The specific surface area of ​​the alkaline earth metal aluminate particles measured by the BET method is 0.1 m². 2 / g or more 2.0m 2 Within the range of / g or less, it readily bonds with the rare earth aluminate phosphor crystal phase, dispersing light in the sintered body and improving the strength of the sintered body obtained by bonding the rare earth aluminate phosphor crystal phase as a binder.

[0045] In preparing the raw material mixture, the raw material mixture comprises alkaline earth metal aluminate particles and at least one rare earth element R selected from the group consisting of Y, La, Gd, Lu, and Tb. 1 The material comprises a first oxide particle containing a cerebrospinal fluid, a second oxide particle containing a cerebrospinal fluid, and a third oxide particle containing an algae, and optionally contains at least one element M selected from the group consisting of Ga and Sc. 1 It contains fourth oxide particles, which include the rare earth element R. The oxide particles contained in the raw material mixture are specifically the rare earth element R. 1 Oxides containing this element include Y2O3, La2O3, Gd2O3, Lu2O3, and Tb2O3. Also, Al2O3 and CeO2 are examples. The element M may be included as needed.1 Oxides containing this include Ga2O3 and Sc2O3.

[0046] Rare earth element R contained in the raw material mixture 1 Primary oxide particles containing , secondary oxide particles containing Ce, tertiary oxide particles containing Al, and optionally containing element M 1 It is preferable that the fourth oxide particles containing are included in the raw material mixture in a molar ratio that results in a composition represented by formula (I). Rare earth element R 1 If two or more types are included, the raw material mixture may contain two types of primary oxide particles, such as primary oxide particle a and primary oxide particle b.

[0047] The raw material mixture, in its initial composition, contains the rare earth element R per mole of composition. 1 The molar ratio of the total of and Ce is 3, and the molar ratio of Ce is the product of a variable m between 0.002 and 0.02 and 3, and Al or Al and element M which may be included as needed. 1 The total molar ratio of the elements is the product of 5 and a variable k between 0.95 and 1.10, so that the rare earth elements R 1 A first oxide particle containing a , a second oxide particle containing Ce, a third oxide particle containing Al, and optionally containing element M 1 It is preferable to mix it with quaternary oxide particles containing the above.

[0048] The raw material mixture preferably contains alkaline earth metal aluminate particles in an amount of 0.1% to 15% by mass when the total amount of the raw material mixture is 100% by mass. More preferably, the raw material mixture contains alkaline earth metal aluminate particles in an amount of 0.2% to 14% by mass, even more preferably in an amount of 0.3% to 13% by mass, even more preferably in an amount of 0.4% to 12% by mass, and particularly preferably in an amount of 0.5% to 10% by mass when the total amount of the raw material mixture is 100% by mass. When the raw material mixture contains alkaline earth metal aluminate particles in an amount of 0.1% to 15% by mass when the total amount of the raw material mixture is 100% by mass, it contains a rare earth aluminate phosphor crystalline phase, an alkaline earth metal aluminate crystalline phase, and an aluminum oxide crystalline phase, and the alkaline earth metal aluminate crystalline phase scatters incident light, increasing the luminescence efficiency and allowing for the production of a high-strength sintered body.

[0049] In preparing the raw material mixture, the raw material mixture consists of alkaline earth metal aluminate particles and rare earth element R 1 Primary oxide particles containing , secondary oxide particles containing Ce, tertiary oxide particles containing Al, and element M as needed. 1The quaternary oxide particles containing the above may be mixed wet or dry. A ball mill or other device may be used for mixing. Examples of liquids used for wet mixing include deionized water, water, and ethanol. The amount of liquid used for wet mixing is preferably in the range of 10 to 200 parts by mass, and may also be in the range of 50 to 150 parts by mass, based on 100 parts by mass of the raw material mixture. If wet mixing is performed, the mixture may be dried to obtain the raw material mixture. When wet mixing is performed, the raw material mixture may contain a dispersant. An organic dispersant can be used, and cationic dispersants, anionic dispersants, and nonionic dispersants can be used. The amount of dispersant is preferably such that it volatilizes by heating, degreasing, or heat treatment, and is preferably 10% by mass or less of the dispersant per 100% by mass of the raw material mixture, but may also be 5% by mass or less, or 3% by mass or less. The drying temperature may be in the range of 50°C to 150°C, and the drying time may be 1 hour to 20 hours.

[0050] A method for manufacturing a wavelength conversion member includes molding a raw material mixture to obtain a molded body. In obtaining the molded body, known methods such as press molding can be used to mold the raw material mixture. Examples of press molding methods include die press molding and cold isostatic pressing (CIP), a term defined in JIS Z2500:2000, No. 2109. Alternatively, the body may be molded by uniaxial compression. To shape the molded body, two methods may be employed; for example, die press molding may be performed followed by CIP, or uniaxial compression using a roller bench may be performed followed by CIP. For CIP, it is preferable to press the molded body using cold isostatic pressing with water as the medium.

[0051] The pressure during die press forming or when forming by uniaxial compression is preferably in the range of 5 MPa to 60 MPa, and more preferably in the range of 5 MPa to 50 MPa. If the pressure during die press forming or when forming by uniaxial compression is within the above range, the molded body can be shaped into the desired form.

[0052] The pressure in CIP is preferably in the range of 50 MPa to 200 MPa, and more preferably in the range of 50 MPa to 180 MPa. When the pressure in CIP is in the range of 50 MPa to 200 MPa, a sintered body containing a rare earth aluminate phosphor crystalline phase, an alkaline earth metal aluminate crystalline phase, and an aluminum oxide crystalline phase can be obtained after firing.

[0053] The molded body obtained by molding the raw material mixture may be degreased by heating to remove dispersants and other substances. When degreasing the molded body by heating, it is preferable to heat it in an air and nitrogen atmosphere within a range of 500°C to 1000°C. Heating in an air and nitrogen atmosphere within a range of 500°C to 1000°C reduces the amount of carbon contained in the molded body, thereby suppressing the decrease in luminous flux caused by the presence of carbon.

[0054] A method for manufacturing a wavelength conversion member includes firing a molded body to obtain a sintered body. In firing a molded body to obtain a sintered body, the firing temperature (temperature inside the firing furnace) is preferably in the range of 1600°C to 1800°C, more preferably in the range of 1620°C to 1790°C, even more preferably in the range of 1650°C to 1780°C, and may also be in the range of 1650°C to 1750°C. When firing the molded body, if the firing temperature is 1600°C or higher, the alkaline earth metal aluminate particles do not react with the rare earth aluminate phosphor crystal phase, and a sintered body containing the rare earth aluminate phosphor crystal phase, the alkaline earth metal aluminate crystal phase, and the aluminum oxide crystal phase can be obtained. When firing the molded body, if the firing temperature is 1800°C or lower, a sintered body can be obtained that contains a rare earth aluminate phosphor crystal phase, an alkaline earth metal aluminate crystal phase, and an aluminum oxide crystal phase, without the alkaline earth metal aluminate particles decomposing or dissolving to the point where the grain boundaries of each crystal phase disappear, while still allowing the grain boundaries of each crystal phase to be distinguished.

[0055] When firing the molded body, it is preferable to do so in an oxygen-containing atmosphere. The oxygen content in the atmosphere is preferably 5% by volume or more, more preferably 10% by volume or more, and even more preferably 15% by volume or more. The molded body may also be fired in an atmosphere of air (oxygen content of 20% by volume or more). In an atmosphere with an oxygen content of less than 1% by volume, the surface of the oxide may be difficult to melt. The amount of oxygen in the atmosphere may be measured, for example, by the amount of oxygen flowing into the firing apparatus, or it may be measured at a temperature of 20°C and a pressure of atmospheric pressure (101.325 kPa). The pressure when firing the molded body may also be atmospheric pressure (101.325 kPa).

[0056] The resulting sintered body may be cut to a desired size or thickness. Known methods can be used for cutting, such as blade dicing, laser dicing, or cutting with a wire saw.

[0057] The resulting sintered body may be surface-treated. Surface treatment involves treating the surface of the cut piece obtained by cutting the resulting sintered body. This surface treatment not only makes the surface of the sintered body suitable for improving the efficiency of light extraction, but also allows the sintered body to be shaped to a desired size, size, or thickness, either in combination with the above-mentioned processing or by surface treatment alone. Surface treatment may be performed before or after cutting the sintered body to the desired size or thickness. Examples of surface treatment methods include sandblasting, mechanical grinding, dicing, and chemical etching.

[0058] The manufacturing method described above yields a sintered body containing a rare earth aluminate phosphor crystalline phase, an alkaline earth metal aluminate crystalline phase, and an aluminum oxide crystalline phase. The rare earth aluminate phosphor crystalline phase contained in the sintered body obtained by the manufacturing method described above preferably has the composition represented by formula (I).

[0059] Preferably, the resulting sintered body contains a rare-earth aluminate phosphor crystal phase having the composition represented by formula (I). Preferably, the sintered body emits light having an emission peak wavelength in the range of 500 nm to less than 650 nm, when excitation light in the wavelength range of 350 nm to 500 nm is wavelength-converted by the rare-earth aluminate phosphor crystal phase having the composition represented by formula (I).

[0060] A method for manufacturing a wavelength conversion member preferably includes forming an optical thin film on a sintered body.

[0061] Figure 2 is a flowchart illustrating the method for manufacturing a wavelength conversion member. The method for manufacturing a wavelength conversion member includes preparing alkaline earth metal aluminate particles (S101), preparing a raw material mixture (S102), molding the raw material mixture to obtain a molded body (S103), firing the molded body to obtain a sintered body (S104), and depositing an optical thin film on the sintered body (S105).

[0062] In forming an optical thin film, if the optical thin film is a single film made of a single material, the material used to form the optical thin film may be a fluoride or silicon dioxide containing at least one element selected from the group consisting of alkali metal elements, alkaline earth metal elements, and Group 13 metal elements. Examples of fluorides include MgF2, CaF2, SrF2, AlF3, Na3AlF6, and Na5Al3F 14 Examples include LiF, NaF, and KF. Fluorides include MgF2, CaF2, SrF2, AlF3, Na3AlF6, and Na5Al3F 14 This includes at least one selected from the group consisting of NaF and LiF.

[0063] When the optical thin film is a dielectric multilayer film, the method for manufacturing the wavelength conversion member preferably includes, in forming the optical thin film, forming a first dielectric layer and forming a second dielectric layer having a different refractive index from the first dielectric layer.

[0064] In forming an optical thin film, the dielectric material constituting the first dielectric layer can be selected from, for example, SiO2, Al2O3, and a dielectric material commonly called SiAlON. The dielectric material constituting the second dielectric layer can be selected from, for example, TiO2, Nb2O5, Ta2O5, and Zr2O5.

[0065] Optical thin films can be deposited by chemical vapor deposition or physical vapor deposition. Examples of physical vapor deposition methods include electron beam (EB) deposition, atomic layer deposition (ALD), resistance heating deposition, ion plating, and sputtering. When the optical thin film is a dielectric multilayer film, it is preferable to alternately deposit the first dielectric layer and the second dielectric layer using electron beam (EB) heating deposition or ALD.

[0066] In a method for manufacturing a wavelength conversion member, if a translucent member is provided, the method may include forming the translucent member. If the translucent member is made of resin, it can be formed, for example, by a printing method. If the translucent member is made of an inorganic material such as glass or sapphire, it can be formed by bonding or the like.

[0067] The resulting wavelength conversion component can be used in combination with a light source as a wavelength conversion component for automotive light sources, general lighting devices, backlights for liquid crystal display devices, and light sources for projectors.

[0068] The light-emitting device preferably comprises the aforementioned wavelength conversion member and a light-emitting element having an emission peak wavelength in the range of 365 nm to 500 nm, which irradiates the aforementioned wavelength conversion member.

[0069] Figure 3 shows an example of a light-emitting device and is a schematic plan view of the light-emitting device 100, and Figure 4 is a schematic cross-sectional view of the light-emitting device 100 shown in Figure 3 along the line IIIB-IIIB'. The light-emitting device 100 comprises a light-emitting element 20 made of an LED or LD and a wavelength conversion member 30 made of a ceramic composite that is excited by light from the light-emitting element 20 and emits light. The light-emitting element 20 is flip-chip mounted on a substrate 10 via a bump which is a conductive member 60. The wavelength conversion member 30 is provided on the light-emitting surface of the light-emitting element 20 via an adhesive layer 40. The light-emitting element 20 and the wavelength conversion member 30 are covered on their sides by a covering member 50 which reflects light. The light-emitting element 20 can emit light by receiving power from outside the light-emitting device 100 via wiring and conductive member 60 formed on the substrate 10. The light-emitting device 100 may include semiconductor elements 70 such as protective elements to prevent the light-emitting element 20 from being destroyed by the application of excessive voltage. The covering member 50 is provided, for example, to cover the semiconductor element 70. The covering member 50 may contain a resin 51 and at least one additive 52 selected from the group consisting of colorants, phosphors, and fillers. The following describes each component used in the light-emitting device. Further details can be found in, for example, the disclosure in Japanese Patent Application Publication No. 2014-112635.

[0070] The light-emitting element can be, for example, a semiconductor light-emitting element using a nitride-based semiconductor, such as an LED chip or an LD chip. The light-emitting element preferably has an emission peak wavelength in the range of 380 nm to 500 nm, more preferably in the range of 390 nm to 495 nm, even more preferably in the range of 400 nm to 490 nm, and particularly preferably in the range of 420 nm to 490 nm. The light-emitting element is provided with a p electrode and an n electrode. The p electrode and n electrode of the light-emitting element may be formed on the same side of the light-emitting element or on different sides. The light-emitting element may be flip-chip mounted.

[0071] The wavelength conversion member can be the wavelength conversion member described above. The wavelength conversion member only needs to be large enough so that the sintered body provided in the wavelength conversion member completely covers the light extraction surface of the light-emitting element. An adhesive layer may be interposed between the light-emitting element and the wavelength conversion member, or the light-emitting element and the wavelength conversion member may be fixed together with the adhesive layer. The adhesive constituting 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.

[0072] The substrate is preferably made of an insulating material that does not easily transmit light from the light-emitting element or ambient light. Examples of substrate materials include ceramics such as aluminum oxide and aluminum nitride, and resins such as phenolic resin, epoxy resin, polyimide resin, bismaleimidotriazine resin (BT resin), and polyphthalamide (PPA) resin. Ceramics are preferred as substrate materials because of their high heat resistance.

[0073] An adhesive layer is interposed between the light-emitting element and the wavelength conversion member to fix them together. The adhesive constituting the adhesive layer is preferably made of a material capable of optically connecting 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.

[0074] Semiconductor elements that may be provided in a light-emitting device as needed include, for example, transistors for controlling light-emitting elements and protective elements to suppress damage or performance degradation of light-emitting elements due to excessive voltage application. Examples of protective elements include Zener diodes and capacitors.

[0075] As the material for the coating member, an insulating material is preferable. More specifically, examples include phenolic resin, epoxy resin, bismaleimidotriazine resin (BT resin), polyphthalamide (PPA) resin, and silicone resin. The coating member may optionally contain at least one additive selected from the group consisting of colorants, phosphors, and fillers.

[0076] As a conductive component, bumps can be used. As the material for the bumps, Au or its alloys can be used, and as other conductive components, eutectic solder (Au-Sn), Pb-Sn, lead-free solder, etc., can be used.

[0077] An example of a method for manufacturing a light-emitting device is described below. For further details, please refer to, for example, the disclosures in Japanese Patent Publication No. 2014-112635 or Japanese Patent Publication No. 2017-117912. The method for manufacturing a light-emitting device preferably includes a process for arranging light-emitting elements, a process for arranging semiconductor elements as needed, a process for forming a wavelength conversion member including a ceramic composite, a process for bonding the light-emitting elements and the wavelength conversion member, and a process for forming a coating member. The process for arranging the light-emitting device involves arranging and mounting the light-emitting elements on a substrate. The light-emitting elements and semiconductor elements are, for example, flip-chip mounted on the substrate. The process for bonding the light-emitting elements and the wavelength conversion member involves placing the wavelength conversion member opposite the light-emitting surface of the light-emitting element and bonding the wavelength conversion member to the light-emitting element with an adhesive layer. The process for forming a coating member involves covering the sides of the light-emitting element and the wavelength conversion member, excluding the light-emitting surface, with a coating member composition, thereby forming a coating member on the sides of the light-emitting element and the wavelength conversion member, excluding the light-emitting surface. This coating member is intended to reflect the light emitted from the light-emitting element and is formed to cover the sides of the wavelength conversion member without covering the light-emitting surface, and to embed the semiconductor element. In this way, the light-emitting devices shown in Figures 3 and 4 can be manufactured. [Examples]

[0078] The present invention will be described in detail below with reference to examples. The present invention is not limited to these examples.

[0079] Examples of production methods for alkaline earth metal aluminate particles Barium carbonate (BaCO3) and aluminum oxide (Al2O3) were weighed to form BaAl2O4, and 2 parts by mass of a dispersant (S-Ream-2093I, NOF Corporation) were added to a total of 100 parts by mass. Further, 50 parts by mass of ethanol were added to prepare the raw material mixture. The raw material mixture was stirred in a wet ball mill for 15 hours to prepare a slurry-like raw material mixture in which barium carbonate (BaCO3) and aluminum oxide (Al2O3) were uniformly mixed. The resulting slurry-like raw material mixture was dried in an air atmosphere at 90°C for 8 hours to obtain a powder-like raw material mixture. The dried raw material mixture was roasted in a calcination furnace (manufactured by Marusho Electric Co., Ltd.) to synthesize BaAl2O4. Alkaline earth metal aluminate particles with the composition represented by BaAl2O4 were prepared by crushing roasted BaAl2O4 powder in a dry ball mill for 1 hour and removing coarse particles by passing it through a #150 sieve. The prepared alkaline earth metal aluminate particles had a specific surface area of ​​0.72 m² as measured by the BET method. 2 It is / g.

[0080] As the first oxide particles, yttrium oxide particles with a purity of 98% by mass were used.

[0081] As the second oxide particles, cerium oxide particles with a purity of 92% by mass were used.

[0082] As the third oxide particles, aluminum oxide particles with a purity of 99% by mass were used.

[0083] Example 1 The molar ratio of each element Y, Gd, Al, and Ce contained in each oxide particle is (Y 0.888 Gd 0.107 Ce 0.005 )3Al5O 12To obtain the composition represented by , yttrium oxide particles were weighed as one of the two types of primary oxide particles, primary oxide particle a, gadolinium oxide particles as the other primary oxide particle b, cerium oxide particles as secondary oxide particles, and aluminum oxide particles as tertiary oxide particles. Furthermore, alkaline earth metal aluminate particles having the composition represented by BaAl2O4 were weighed in at a concentration of 0.5% by mass when the total amount of the raw material mixture is 100% by mass. A raw material mixture was prepared containing primary oxide particles a containing Y, primary oxide particles b containing Gd, secondary oxide particles containing Al, tertiary oxide particles containing Ce, and alkaline earth metal aluminate particles having the composition represented by BaAl2O4. 100 parts by mass of the raw material mixture was mixed with 2.0 parts by mass of a dispersant (Floren G-700, Kyoeisha Chemical Co., Ltd.), and then 50 parts by mass of ethanol, and the mixture was wet-mixed using a ball mill to obtain the mixture.

[0084] The resulting mixture is filled into a mold at 5 MPa (51 kgf / cm²). 2 A cylindrical molded body with a diameter of 24 mm and a thickness of 8 mm was formed using the pressure of ). The obtained molded body was placed in a packaging container, vacuum-packed, and subjected to CIP at 176 MPa using a cold isostatic pressurizing device (manufactured by Kobe Steel, Ltd. (KOBELCO)) to obtain a molded body.

[0085] The molded body obtained by molding was fired in a firing furnace (manufactured by Marusho Electric Co., Ltd.) to obtain a sintered body. The firing conditions were an air atmosphere (101.325 kPa, oxygen concentration: approximately 20 vol%), a temperature of 1685°C, and a firing time of 6 hours. The obtained sintered body was cut into appropriate shapes and sizes with a wire saw, and then the surface of the cut pieces was polished with a surface grinder. A sintered body according to Example 1 was then obtained. The sintered body according to Example 1 was used as a wavelength conversion member. The sintered body according to Example 1 is Y 2.665 Gd 0.32 Ce 0.015 Al 5.1 O 12 ((Y 0.888 Gd 0.107 Ce 0.005 )3Al 5.1 O 12It included a rare earth aluminate phosphor crystal phase having a composition represented by ), an alkaline earth metal aluminate crystal phase having a composition represented by BaAl2O4, and an aluminum oxide (Al2O3) crystal phase. Y 2.665 Gd 0.32 Ce 0.015 Al 5.1 O 12 The refractive index of the rare earth aluminate phosphor crystal phase having a composition represented by is 1.83, the refractive index of the alkaline earth metal aluminate crystal phase having a composition represented by BaAl2O4 is 1.68, and the refractive index of the aluminum oxide (Al2O3) crystal phase is 1.77. Y of the rare earth aluminate phosphor crystal phase 2.665 Gd 0.32 Ce 0.015 [[ID=No. 16]]Al 5.1 O 12 The composition represented by satisfies the composition represented by the above formula (I), R 1 is Y and Gd, n is 0.005 (n = 0.005), the molar ratio of Ce represented by the product of n and 3 in 1 mol of the composition is 0.015, m is 0 (m = 0), and k is 1.02 (k = 1.02).

[0086] Example 2 The molar ratios of the elements Y, Gd, Al, and Ce contained in each oxide particle are (Y 0.882 Gd 0.113 Ce 0.005 )3Al5O 12 To obtain a composition represented by , yttrium oxide particles were used as one type of the first oxide particles a among the two types of the first oxide particles, gadolinium oxide particles were used as the other type of the first oxide particles b, cerium oxide particles were used as the second oxide particles, and aluminum oxide particles were used as the third oxide particles. The amounts were measured so that the molar ratios of the elements Y, Gd, Al, and Ce contained in each oxide particle were as described above. In addition, alkaline earth metal aluminate particles having a composition represented by BaAl2O4 were measured to contain 2% when the total amount of the raw material mixture was 100% by mass, and a raw material mixture was prepared. Except for this, in the same manner as in Example 1, a sintered body according to Example 2 was obtained. The sintered body according to Example 2 was used as a wavelength conversion member. The sintered body according to Example 2 is Y 2.645 Gd 0.34 Ce 0.015 [[ID=No. 42]]Al 5.1 O12 ((Y 0.882 Gd 0.113 Ce 0.005 )3Al 5.1 O 12 ) and an alkaline earth metal aluminate crystal phase having a composition represented by BaAl2O4, and an aluminum oxide (Al2O3) crystal phase. Y 2.645 Gd 0.34 Ce 0.015 Al 5.1 O 12 The refractive index of the rare earth aluminate phosphor crystal phase having the composition represented by is 1.83. Y of the rare earth aluminate phosphor crystal phase 2.645 Gd 0.34 Ce 0.015 Al 5.1 O 12 The composition represented by satisfies the composition represented by the above formula (I), R 1 is Y and Gd, n is 0.005 (n = 0.005), the molar ratio of Ce represented by the product of n and 3 in 1 mol of the composition is 0.015, m is 0 (m = 0), and k is 1.02 (k = 1.02).

[0087] Example 3 When the total amount of the raw material mixture was 100% by mass, an alkaline earth metal aluminate particle having a composition represented by BaAl2O4 was weighed so as to contain 5% by mass, and a sintered body according to Example 3 was obtained in the same manner as in Example 2 except that the raw material mixture was prepared. The sintered body according to Example 3 was used as the wavelength conversion member.

[0088] Example 4 When the total amount of the raw material mixture was 100% by mass, an alkaline earth metal aluminate particle having a composition represented by BaAl2O4 was weighed so as to contain 8% by mass, and a sintered body according to Example 4 was obtained in the same manner as in Example 2 except that the raw material mixture was prepared. The sintered body according to Example 4 was used as the wavelength conversion member.

[0089] Example 5 A sintered body according to Example 5 was obtained in the same manner as in Example 1, except that the raw material mixture was prepared by weighing out 10% by mass of alkaline earth metal aluminate particles having a composition represented by BaAl2O4, when the total amount of the raw material mixture was 100% by mass. The sintered body according to Example 5 was used as a wavelength conversion member.

[0090] Comparative Example 1 The molar ratio of each element Y, Gd, Al, and Ce contained in each oxide particle is (Y 0.888 Gd 0.107 Ce 0.005 )3Al5O 12 A raw material mixture was prepared by weighing yttrium oxide particles as one of the two types of primary oxide particles, gadolinium oxide particles as the other primary oxide particle b, cerium oxide particles as the secondary oxide particles, and aluminum oxide particles as the tertiary oxide particles, so that the composition would be represented by [formula]. In Comparative Example 1, the raw material mixture did not contain alkaline earth metal aluminate particles. Except for using a raw material mixture that did not contain alkaline earth metal aluminate particles, a molded body was obtained in the same manner as in Example 1, and fired in the same manner as in Example 1 to obtain a sintered body according to Comparative Example 1. The sintered body according to Comparative Example 1 was used as a wavelength conversion member. The sintered body according to Comparative Example 1 is Y 2.665 Gd 0.32 Ce 0.015 Al 5.1 O 12 ((Y 0.888 Gd 0.107 Ce 0.005 )3Al 5.1 O 12 It contained a rare-earth aluminate phosphor crystalline phase having the composition represented by ) and an aluminum oxide (Al2O3) crystalline phase.

[0091] Comparative Example 2 A sintered body according to Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that the particle size of the aluminum oxide raw material used was different. Due to the change in the aluminum oxide raw material, the sintered body according to Comparative Example 2 had a different relative density from that of Comparative Example 1, and had more voids or cavities. The sintered body according to Comparative Example 2 was used as a wavelength conversion member.

[0092] Comparative Examples 3 to 8 The sintered bodies according to Comparative Examples 3 to 8 were obtained in the same manner as in Comparative Example 2, except that the firing temperature of the molded body was set to the temperatures shown in Table 2. The sintered body according to Comparative Example 3 was fired at a higher temperature than Comparative Example 2, resulting in a relative density equivalent to that of Comparative Example 2. The sintered bodies according to Comparative Examples 4 to 8 were fired at a lower temperature than Comparative Example 2, resulting in a different relative density from that of Comparative Example 2 and an increase in voids or cavities due to the change in firing temperature. Each of the sintered bodies according to Comparative Examples 3 to 8 was used as a wavelength conversion member.

[0093] The following evaluations were performed on each wavelength conversion member in the examples and comparative examples. In Table 1, the symbol "-" indicates that there is no corresponding item or value.

[0094] Volume percentage of alkaline earth metal aluminate (BaAl2O4) crystalline phase For each sintered body of the wavelength conversion member in the examples and comparative examples, the surface or cross-section was photographed using a scanning electron microscope (SEM). In the SEM images obtained, the total area of ​​the alkaline earth metal aluminate crystal phase was measured using Winroof2018 image analysis software (manufactured by Mitani Corporation), and the area ratio was calculated when the measurement area on the surface or cross-section of the sintered body was set to 100% area. Similarly, the area ratios of the rare earth aluminate phosphor crystal phase and the aluminum oxide crystal phase were also calculated. The area measured using the scanning electron microscope (SEM) in the SEM images was 1257 μm². 2The measurement area on the surface or cross-section of the sintered body is equivalent to 100% area of ​​the total of the rare earth aluminate phosphor crystalline phase, alkaline earth metal aluminate crystalline phase, and aluminum oxide crystalline phase. Furthermore, since the rare earth aluminate phosphor crystalline phase, alkaline earth metal aluminate crystalline phase, and aluminum oxide crystalline phase are also present in the thickness direction of the sintered body, the numerical value of the area ratio of the alkaline earth metal aluminate crystalline phase on the surface or cross-section of each sintered body is approximately the same as the numerical value of the volume ratio of the alkaline earth metal aluminate crystalline phase in the sintered body. The numerical value of the area ratio of the alkaline earth metal aluminate crystalline phase on the surface or cross-section of each sintered body was defined as the numerical value of the volume ratio (volume %) of the alkaline earth metal aluminate crystalline phase when the total of the rare earth aluminate phosphor crystalline phase, alkaline earth metal aluminate crystalline phase, and aluminum oxide crystalline phase on the surface or cross-section of each sintered body is set to 100% volume. In this specification, the cross-section of a sintered body that has been cut and surface-treated may also be described as the surface of the sintered body or the surface of the test piece.

[0095] Relative density (%) The relative density of each sintered body of each wavelength conversion member in the examples and comparative examples was measured. The relative density of each sintered body of each wavelength conversion member in the examples and comparative examples was calculated using the above-mentioned formula (1). The apparent density of each sintered body was calculated using the above-mentioned formula (2). The true density of each sintered body was calculated using the above-mentioned formula (3). The true density of the rare earth aluminate phosphor contained in the rare earth aluminate phosphor crystal phase was 4.60 g / cm³. 3 The true density of alkaline earth metal aluminates contained in the alkaline earth metal aluminate crystalline phase having a composition represented by BaAl2O4 is 4.00 g / cm³. 3 The true density of aluminum oxide (Al2O3) is 3.99 g / cm³. 3 That is the case.

[0096] Relative luminescence intensity (%) Test specimens for measuring the relative luminescence intensity of each sintered body of each wavelength conversion member in the examples and comparative examples were formed by cutting a specimen to a size of 1.1 mm in width, 1.1 mm in height, and 80 μm in thickness. For each sample of each sintered body of each wavelength conversion member in the examples and comparative examples, a laser beam with a wavelength of 450 nm was irradiated from a laser diode so that the diameter of the incident beam was 2.2 mm, and the luminance of the light emitted from the side opposite to the side into which the laser beam was incident was measured with an integrating sphere and defined as the luminescence intensity. The luminescence intensity of the sintered body of Comparative Example 1 was set to 100%, and the luminescence intensities measured for each sample of the sintered bodies in Examples 1 to 5 and each sample of the sintered body in Comparative Example 2 were expressed as relative luminescence intensity (%) relative to the luminescence intensity of Comparative Example 1.

[0097] Measurement of breaking strength Test specimens of each sintered body of the wavelength conversion member according to the examples and comparative examples were prepared, and their fracture strength was measured under the following conditions. The test specimens for measuring the fracture strength of each sintered body of the wavelength conversion member according to the examples and comparative examples were cut to a size of 2 mm in length, 11 mm in width (length), and 0.3 mm in thickness to create rectangular parallelepiped test specimens. Figure 5 shows a graph illustrating the relationship between the relative density and fracture strength of each sintered body of the wavelength conversion member according to the examples and comparative examples. Figure 6 shows a graph illustrating the relationship between the relative luminescence intensity and fracture strength of each sintered body of the wavelength conversion member according to the examples and comparative examples. Figure 7 shows a graph illustrating the relationship between the transmittance and fracture strength of each sintered body of the wavelength conversion member according to the examples and comparative examples, which will be described later. Measurement conditions for fracture strength The test method involved a three-point bending test, using the aforementioned rectangular specimen with a support distance of 10 mm, and a testing machine with a measuring stand (manufactured by IMADA Corporation) at a head speed of 1 mm / min. The strength was measured using a digital force analyzer (manufactured by IMADA Corporation).

[0098] Transmittance (%) Test specimens of each sintered body of the wavelength conversion member according to the examples and comparative examples were prepared, and their transmittance was measured under the following conditions. Test specimens for measuring the transmittance of each sintered body of the wavelength conversion member according to Example 1 and Example 5 were formed by cutting into a disc with a diameter of 23 mm and a thickness of 230 μm. Test specimens for measuring the transmittance of each sintered body of the wavelength conversion member according to Example 2 to 4 and each sintered body of the wavelength conversion member according to Comparative Examples 1 to 8 were formed by cutting into a disc with a diameter of 23 mm and a thickness of 300 μm. Using a spectrophotometer (manufactured by Hitachi High-Tech Science Co., Ltd.), the light from the light source was converted into monochromatic light with a wavelength of 550 nm using a spectrometer. The light intensity of the converted 550 nm light was measured and defined as the incident light intensity. Light with a wavelength of 550 nm was then incident on each sintered body of the wavelength conversion member in the examples and comparative examples. The light intensity of the light emitted from each sintered body opposite the incident side was measured and defined as the transmitted light intensity. The ratio of the transmitted light intensity to the incident light intensity was measured as the transmittance for 550 nm light based on the following formula (4). In the following formula (4), I0 is the incident light intensity, and I is the transmitted light intensity at each wavelength. For each sintered body of the wavelength conversion member in Example 1 and Example 5, the measured transmittance of a sintered body with a thickness of 230 μm was converted to the measured transmittance of a sintered body with a thickness of 300 μm. Specifically, the transmittance of each sintered body of each wavelength conversion member according to Example 1 and Example 5 was multiplied by the ratio of the transmittance of the sintered body of Example 3 at 300 μm thickness to the transmittance at 230 μm thickness (transmittance of the sintered body of the wavelength conversion member according to Example 3 at a thickness of 300 μm / transmittance of the sintered body of the wavelength conversion member according to Example 3 at a thickness of 230 μm) to convert it. The transmittances of each sintered body of each wavelength conversion member according to Example 1 and Example 5 listed in Table 1 are converted values ​​obtained by converting the transmittance of the sintered body with a thickness of 230 μm to the value of the sintered body with a thickness of 300 μm as described above.

[0099]

number

[0100] SEM image A scanning electron microscope (SEM) was used to obtain SEM images of the surfaces of each sintered body of the wavelength conversion member in the examples and comparative examples. The SEM images shown in the figures were obtained at a magnification of 1000x. Figure 8 is an SEM image of the surface of the sintered body of the wavelength conversion member according to Example 1. Figure 9 is an SEM image of the surface of the sintered body of the wavelength conversion member according to Example 4. Figure 10 is an SEM image of the surface of the sintered body of the wavelength conversion member according to Comparative Example 1. Figure 11 is an SEM image of the surface of the sintered body of the wavelength conversion member according to Comparative Example 2.

[0101] [Table 1]

[0102] [Table 2]

[0103] The sintered bodies of the wavelength conversion members according to Examples 1 to 5 contain an alkaline earth metal aluminate crystal phase, and exhibit higher relative emission intensity compared to the sintered body of the wavelength conversion member according to Comparative Example 1, which does not contain an alkaline earth metal aluminate crystal phase. In the wavelength conversion members according to Examples 1 to 5, the alkaline earth metal aluminate crystal phase contained in the sintered body scatters the light incident on the sintered body, and the rare earth aluminate phosphor crystal phase efficiently converts the wavelength, enabling the emission of light with high emission intensity. The sintered bodies of the wavelength conversion members according to Examples 1 to 5 can increase emission intensity. The sintered bodies of the wavelength conversion members according to Examples 2, 3, and 4 maintain high fracture strength and mechanical strength even when the relative density is relatively low.

[0104] Figure 5 is a graph showing the relationship between the relative density and fracture strength of each sintered body of the wavelength conversion member in the examples and comparative examples. The relative density of the sintered body of the wavelength conversion member in Example 1 is similar to that of each sintered body of the wavelength conversion member in Comparative Examples 1 to 3. The relative density of each sintered body of the wavelength conversion member in Examples 2 to 4 is lower than that of the sintered body of the wavelength conversion member in Comparative Example 2, but the fracture strength of each sintered body of the wavelength conversion member in Examples 2 to 4 is higher than that of the sintered body of the wavelength conversion member in Comparative Example 2. Comparing the fracture strength of two sintered bodies with similar relative densities for the sintered bodies of the wavelength conversion member in the examples and the sintered bodies of the wavelength conversion member in the comparative examples, the relative density of the sintered body in Example 2 is 98.8%, which is similar to the relative density of the sintered body in Comparative Example 6, which is 98.7%. The fracture strength of the sintered body in Example 2 is 5.658 N, which is higher than the fracture strength of the sintered body in Comparative Example 6, which is 3.585 N. Compared to the case where light is scattered by voids or pores contained in each sintered body of each wavelength conversion member in Comparative Examples 2 to 8, the sintered bodies of the wavelength conversion members in Examples 2, 3, and 4, which scatter light by the alkaline earth metal aluminate crystalline phase, have higher fracture strength and higher mechanical strength.

[0105] Figure 6 is a graph showing the relationship between the relative luminescence intensity and fracture strength of each sintered body of the wavelength conversion member in the examples and comparative examples. Each sintered body of the wavelength conversion member in Examples 2, 3, and 4 scatters light due to the alkaline earth metal aluminate crystal phase, resulting in a higher relative luminescence intensity than the sintered body of the wavelength conversion member in Comparative Example 1, which has a higher relative density and fracture strength. Each sintered body of the wavelength conversion member in Examples 2, 3, and 4 scatters light due to the alkaline earth metal aluminate crystal phase contained in the sintered body, resulting in a higher fracture strength and mechanical strength than the sintered body of the wavelength conversion member in Comparative Example 2, which has a higher relative luminescence intensity due to light scattering by voids or pores.

[0106] Figure 7 is a graph showing the relationship between the transmittance of 550 nm light and the fracture strength of each sintered body of the wavelength conversion member in the examples and comparative examples. Compared with the sintered bodies of the wavelength conversion members in Comparative Examples 2 to 6, which have similar transmittance values ​​of 550 nm light, the sintered bodies of the wavelength conversion members in Examples 2, 3, and 4 have higher fracture strength. As shown in the sintered bodies of the wavelength conversion members in Examples 2, 3, and 4, the sintered bodies of the wavelength conversion members in Examples 2, 3, and 4, which scatter light by the alkaline earth metal aluminate crystal phase, have higher fracture strength and higher mechanical strength than the cases where light is scattered by voids or pores contained in the sintered body.

[0107] Figure 8 is an SEM image of the surface of the sintered body of the wavelength conversion member according to Example 1. As shown in Figure 8, the sintered body of the wavelength conversion member according to Example 1 contains a rare earth aluminate phosphor crystal phase 1, an alkaline earth metal aluminate crystal phase 2, and an aluminum oxide crystal phase 3.

[0108] Figure 9 is an SEM image of the surface of the sintered body of the wavelength conversion member according to Example 4. As shown in Figure 9, the sintered body of the wavelength conversion member according to Example 4 contains a rare earth aluminate phosphor crystal phase 1, an alkaline earth metal aluminate crystal phase 2, and an aluminum oxide crystal phase 3. It can be confirmed that the volume proportion of the alkaline earth metal aluminate crystal phase 2 in the sintered body of the wavelength conversion member according to Example 4 is greater than that of the sintered body of the wavelength conversion member according to Example 1.

[0109] The sintered body of the wavelength conversion member according to Comparative Example 1 has a high relative density and contains almost no voids or cavities, resulting in high fracture strength. However, because the incident light is not scattered, the emission intensity is lower than that of the sintered body of the wavelength conversion member according to the Example.

[0110] Figure 10 is an SEM image of the surface of the sintered body of the wavelength conversion member according to Comparative Example 1. As shown in Figure 10, the sintered body of the wavelength conversion member according to Comparative Example 1 contains a rare earth aluminate phosphor crystalline phase 1 and an aluminum oxide crystalline phase 3, and contains voids or cavities 4.

[0111] The sintered body of the wavelength conversion member according to Comparative Example 2 has a lower relative density than that of Comparative Example 1 and contains voids or cavities. These voids or cavities scatter the incident light, resulting in a higher relative emission intensity than that of Comparative Example 1, but a lower fracture strength.

[0112] Figure 11 is an SEM image of the surface of the sintered body of the wavelength conversion member according to Comparative Example 2. As shown in Figure 11, the sintered body of the wavelength conversion member according to Comparative Example 2 contains a rare earth aluminate phosphor crystalline phase 1 and an aluminum oxide crystalline phase 3, and contains voids or cavities 4.

[0113] Embodiments of the present invention include the following wavelength conversion member, light-emitting device, and method for manufacturing the wavelength conversion member.

[0114] [Section 1] A wavelength conversion member comprising a sintered body containing a rare earth aluminate phosphor crystalline phase, an alkaline earth metal aluminate crystalline phase, and an aluminum oxide crystalline phase. [Section 2] The wavelength conversion member according to item 1, wherein when the total of the rare earth aluminate phosphor crystal phase, the alkaline earth metal aluminate crystal phase, and the aluminum oxide crystal phase is taken as 100% by volume, the alkaline earth metal aluminate crystal phase is in the range of 0.1% by volume or more and 10.0% by volume or less. [Section 3] The wavelength conversion member according to claim 1 or 2, wherein the rare earth aluminate phosphor crystalline phase contains at least one element selected from the group consisting of Y, La, Lu, Gd, and Tb. [Section 4] The wavelength conversion member according to any one of claims 1 to 3, wherein the alkaline earth metal aluminate crystalline phase contains at least one element selected from the group consisting of Ba, Sr, and Ca. [Section 5] The wavelength conversion member according to any one of claims 1 to 4, wherein the rare earth aluminate phosphor crystal phase includes a rare earth aluminate phosphor crystal phase having a composition represented by the following formula (I). (R 1 1-n Ce n )3(Al1-m M 1 m ) 5k O 12 (I) (In the above formula (I), R 1 is at least one element selected from the group consisting of Y, La, Lu, Gd, and Tb, and M 1 (where m, n, and k satisfy the following conditions: 0.002 ≤ n ≤ 0.02, 0 ≤ m ≤ 0.4, and 0.95 ≤ k ≤ 1.10, respectively.) [Section 6] The alkaline earth metal aluminate crystalline phase is (Ca,Sr,Ba)Al2O4, (Ca,Sr,Ba)4Al 14 O 25 (Ca,Sr,Ba)Al 12 O 19 (Ca,Sr,Ba)Mg2Al 16 O 27 , and (Ca,Sr,Ba)MgAl 10 O 17 A wavelength conversion member according to any one of claims 1 to 5, having at least one composition selected from the group consisting of the following. [Section 7] A wavelength conversion member according to any one of claims 1 to 6, wherein the sintered body is a plate-like body having one surface and another surface opposite to the first surface, and an optical thin film is provided on at least one of the first surface and the other surface of the sintered body that reflects first light having an emission peak wavelength in the range of 365 nm to 500 nm and transmits second light emitted by the rare earth aluminate phosphor crystal phase which absorbs the first light. [Section 8] The wavelength conversion member according to item 7, wherein the optical thin film is a dielectric multilayer film. [Section 9] The wavelength conversion member according to item 7 or 8, wherein the thickness of the sintered body is in the range of 50 μm or more and 250 μm or less. [Section 10] A light-emitting device comprising a wavelength conversion member as described in any one of items 1 to 9, and a light-emitting element having an emission peak wavelength in the range of 365 nm to 500 nm, which irradiates the wavelength conversion member. [Section 11] Prepare alkaline earth metal aluminate particles, The alkaline earth metal aluminate particles and at least one rare earth element R selected from the group consisting of Y, La, Gd, Lu, and Tb. 1 The material comprises a first oxide particle containing a cerebrospinal fluid, a second oxide particle containing a cerebrospinal fluid, and a third oxide particle containing an algae, and optionally contains at least one element M selected from the group consisting of Ga and Sc. 1 Prepare a raw material mixture which may contain quaternary oxide particles, The aforementioned raw material mixture is molded to obtain a molded body, A method for manufacturing a wavelength conversion member, comprising firing the molded body at a temperature range of 1600°C to 1800°C to obtain a sintered body containing a rare earth aluminate phosphor crystal phase, an alkaline earth metal aluminate crystal phase, and an aluminum oxide crystal phase. [Section 12] The method for producing a wavelength conversion member according to item 11, wherein the raw material mixture contains alkaline earth metal aluminate particles in an amount of 0.1% by mass or more and 15% by mass or less when the raw material mixture is considered to be 100% by mass. [Section 13] The aforementioned raw material mixture, in its composition, contains the rare earth element R 1 The molar ratio of the total of the aforementioned Ce is 3, and the molar ratio of the aforementioned Ce is the product of a variable m of 0.002 or more and 0.02 or less and 3, and the aforementioned Al or the aforementioned Al and an element M which may be included as needed. 1 The total molar ratio of the elements is the product of 5 and a variable k between 0.95 and 1.10, the rare earth elements R 1 A first oxide particle containing the above, a second oxide particle containing the above Ce, a third oxide particle containing the above Al, and optionally element M 1 A method for producing a wavelength conversion member according to item 11 or 12, comprising mixing with fourth oxide particles containing the above. [Section 14] The alkaline earth metal aluminate particles are (Ca,Sr,Ba)Al2O4, (Ca,Sr,Ba)4Al 14 O 25 (Ca,Sr,Ba)Al 12O 19 (Ca,Sr,Ba)Mg2Al 16 O 27 , and (Ca,Sr,Ba)MgAl 10 O 17 A method for manufacturing a wavelength conversion member according to any one of claims 11 to 13, having at least one composition selected from the group consisting of the above. [Section 15] A method for manufacturing a wavelength conversion member according to any one of claims 11 to 14, wherein the sintered body includes a rare earth aluminate phosphor crystal phase having a composition represented by the following formula (I). (R 1 1-n Ce n )3(Al 1-m M 1 m ) 5k O 12 (I) (In the above formula (I), R 1 is at least one element selected from the group consisting of Y, La, Lu, Gd, and Tb, and M 1 (where m, n, and k satisfy the following conditions: 0.002 ≤ n ≤ 0.02, 0 ≤ m ≤ 0.4, and 0.95 ≤ k ≤ 1.10, respectively.) [Section 16] A method for manufacturing a wavelength conversion member according to any one of claims 11 to 15, comprising forming an optical thin film on the sintered body. [Section 17] The method for manufacturing a wavelength conversion member according to claim 16, comprising forming a first dielectric layer and forming a second dielectric layer having a different refractive index from the first dielectric layer, in order to form the optical thin film. [Industrial applicability]

[0115] The wavelength conversion member described herein can be used in combination with an excitation light source as a lighting device for automotive and general lighting applications, a backlight for liquid crystal display devices, a wavelength conversion member for a projector light source, or a light-emitting device. [Explanation of Symbols]

[0116] 1: Rare earth aluminate phosphor crystalline phase, 2: Alkaline earth metal aluminate crystalline phase, 3: Aluminum oxide crystalline phase, 4: Void or void, 10: Substrate, 20: Light-emitting element, 30: Wavelength conversion element, 40: Adhesive layer, 50: Coating element, 60: Conductive element, 70: Semiconductor element, 100: Light-emitting device.

Claims

1. A wavelength conversion member comprising a sintered body containing a rare earth aluminate phosphor crystalline phase, an alkaline earth metal aluminate crystalline phase, and an aluminum oxide crystalline phase.

2. The wavelength conversion member according to claim 1, wherein when the total of the rare earth aluminate phosphor crystal phase, the alkaline earth metal aluminate crystal phase, and the aluminum oxide crystal phase is taken as 100% by volume, the alkaline earth metal aluminate crystal phase is in the range of 0.1% by volume or more and 10.0% by volume or less.

3. The wavelength conversion member according to claim 1, wherein the rare earth aluminate phosphor crystalline phase contains at least one element selected from the group consisting of Y, La, Lu, Gd, and Tb.

4. The wavelength conversion member according to claim 1, wherein the alkaline earth metal aluminate crystalline phase comprises at least one element selected from the group consisting of Ba, Sr, and Ca.

5. The wavelength conversion member according to claim 1, wherein the rare earth aluminate phosphor crystal phase includes a rare earth aluminate phosphor crystal phase having a composition represented by the following formula (I). (R) １ １－ｎ Yes ｎ ) ３ (Al) １－ｍ M １ ｍ ) ５ｋ O １２ (I) (In the above formula (I), R １ is at least one element selected from the group consisting of Y, La, Lu, Gd, and Tb, and M １ (where m, n, and k satisfy the following conditions: 0.002 ≤ n ≤ 0.02, 0 ≤ m ≤ 0.4, and 0.95 ≤ k ≤ 1.10, respectively.)

6. The alkaline earth metal aluminate crystalline phase is (Ca,Sr,Ba)Al ２ O ４ , (Ca, Sr, Ba) ４ Al １４ O ２５ , (Ca,Sr,Ba)Al １２ O １９ , (Ca,Sr,Ba)Mg ２ Al １６ O ２７ , and (Ca,Sr,Ba)MgAl １０ O １７ The wavelength conversion member according to claim 1, having at least one composition selected from the group consisting of the following.

7. The wavelength conversion member according to claim 1, wherein the sintered body is a plate-like body having one surface and another surface facing the first surface, and an optical thin film is provided on at least one of the one surface and the other surface of the sintered body that reflects first light having an emission peak wavelength in the range of 365 nm to 500 nm and transmits second light emitted by the rare earth aluminate phosphor crystal phase which absorbs the first light.

8. The wavelength conversion member according to claim 7, wherein the optical thin film is a dielectric multilayer film.

9. The wavelength conversion member according to claim 7, wherein the thickness of the sintered body is in the range of 50 μm or more and 250 μm or less.

10. A light-emitting device comprising: a wavelength conversion member according to any one of claims 1 to 9; and a light-emitting element having an emission peak wavelength in the range of 365 nm to 500 nm, which irradiates the wavelength conversion member.

11. Prepare alkaline earth metal aluminate particles, The alkaline earth metal aluminate particles and at least one rare earth element R selected from the group consisting of Y, La, Gd, Lu, and Tb. １ The material comprises first oxide particles containing a , second oxide particles containing Ce, and third oxide particles containing Al, and optionally at least one element M selected from the group consisting of Ga and Sc. １ Prepare a raw material mixture which may contain quaternary oxide particles, The aforementioned raw material mixture is molded to obtain a molded body, A method for manufacturing a wavelength conversion member, comprising firing the molded body at a temperature range of 1600°C to 1800°C to obtain a sintered body containing a rare earth aluminate phosphor crystal phase, an alkaline earth metal aluminate crystal phase, and an aluminum oxide crystal phase.

12. The method for manufacturing a wavelength conversion member according to claim 11, wherein the raw material mixture contains alkaline earth metal aluminate particles in an amount of 0.1% by mass or more and 15% by mass or less when the raw material mixture is considered to be 100% by mass.

13. The aforementioned raw material mixture, in its composition, contains the rare earth element R １ The molar ratio of the total of the above Ce is 3, and the molar ratio of the above Ce is the product of a variable m of 0.002 or more and 0.02 or less and 3, and the above Al or the above Al may contain element M as needed. １ The total molar ratio of the elements is the product of 5 and a variable k between 0.95 and 1.10, the rare earth element R １ A first oxide particle containing the above, a second oxide particle containing the above Ce, a third oxide particle containing the above Al, and optionally element M １ A method for producing a wavelength conversion member according to claim 11 or 12, comprising mixing with fourth oxide particles containing the above.

14. The alkaline earth metal aluminate particles are (Ca,Sr,Ba)Al ２ O ４ , (Ca, Sr, Ba) ４ Al １４ O ２５ , (Ca,Sr,Ba)Al １２ O １９ , (Ca,Sr,Ba)Mg ２ Al １６ O ２７ , and (Ca,Sr,Ba)MgAl １０ O １７ A method for manufacturing a wavelength conversion member according to claim 11 or 12, having at least one composition selected from the group consisting of the following.

15. The method for manufacturing a wavelength conversion member according to claim 11 or 12, wherein the sintered body includes a rare earth aluminate phosphor crystal phase having a composition represented by the following formula (I). (R) １ １－ｎ Yes ｎ ) ３ (Al) １－ｍ M １ ｍ ) ５ｋ O １２ (I) (In the above formula (I), R １ is at least one element selected from the group consisting of Y, La, Lu, Gd, and Tb, and M １ (where m, n, and k satisfy the following conditions: 0.002 ≤ n ≤ 0.02, 0 ≤ m ≤ 0.4, and 0.95 ≤ k ≤ 1.10, respectively.)

16. A method for manufacturing a wavelength conversion member according to claim 11 or 12, comprising forming an optical thin film on the sintered body.

17. A method for manufacturing a wavelength conversion member according to claim 16, wherein the optical thin film is formed by forming a first dielectric layer and forming a second dielectric layer having a refractive index different from that of the first dielectric layer.

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