JP6642557B2 - Manufacturing method of wavelength conversion member - Google Patents

Description

  The present invention relates to a method for manufacturing a wavelength conversion member for converting the wavelength of light emitted from a light emitting diode (hereinafter also referred to as “LED”) or a laser diode (hereinafter also referred to as “LD”). About.

  A light-emitting device using an LED as a light-emitting element is used as a light source that replaces an incandescent lamp or a fluorescent lamp because it is a light source with high conversion efficiency, consumes little power, has a long life, and can be downsized. ing. Light emitting devices using LEDs are used not only in lighting fields such as indoor lighting and vehicle lighting, but also in a wide range of fields such as backlight sources for liquid crystals and illuminations. Above all, a light emitting device that emits a mixed color light by combining a light emitting element that emits blue light and a yellow phosphor is excellent in cost and quality, and is widely used.

The phosphor used in the light emitting device is a rare earth aluminate phosphor represented by (Y, Gd, Tb, Lu) ₃ (Al, Ga) ₅ O ₁₂ : Ce, and (Sr, Ca, Ba) ₂ SiO ₄ : Silicate phosphors represented by Eu, Ca-α sialon phosphors, and the like are known.
As a wavelength conversion member, for example, a wavelength conversion member made of a sintered body obtained by mixing a glass powder and an inorganic phosphor powder and melting and solidifying the glass powder is disclosed (Patent Document 1).

JP 2014-234487 A

However, in the wavelength conversion member disclosed in Patent Literature 1, a glass component may be mixed into the inorganic phosphor during the formation of the sintered body, and the light conversion efficiency may be significantly reduced. In addition, when glass is used, it is difficult to obtain a high-density sintered body, pores are present inside the sintered body, and when used in a light emitting device, light conversion efficiency is reduced.
Therefore, an object of one embodiment of the present invention is to provide a method for manufacturing a wavelength conversion member having high emission intensity and high light conversion efficiency.

  Means for solving the above problem include the following aspects.

A first aspect of the present invention is to provide a molded body containing an yttrium aluminum garnet-based phosphor having a composition represented by the following formula (I) and alumina particles having an alumina purity of 99.0% by mass or more. ,
Primary firing of the molded body to obtain a first sintered body,
A method for producing a wavelength conversion member, comprising: secondary firing the first sintered body by hot isostatic pressing (HIP) to obtain a second sintered body.
_{(Y 1-a-b Gd} a Ce b) 3 Al 5 O 12 (I)
(In the formula (I), a and b are numbers satisfying 0 ≦ a ≦ 0.3 and 0 <b ≦ 0.022.)

  According to a second aspect of the present invention, there is provided a compact including an yttrium aluminum garnet-based phosphor and alumina particles having an alumina purity of 99.0% by mass or more. Obtaining a second sintered body by subjecting the first sintered body to secondary sintering by hot isostatic pressing (HIP), and obtaining the second sintered body A method for producing a wavelength conversion member, which includes annealing under a contained atmosphere.

  According to one embodiment of the present invention, it is possible to provide a method of manufacturing a wavelength conversion member having high light emission intensity and high light conversion efficiency.

FIG. 1 is a flowchart illustrating a process sequence of a method for manufacturing a wavelength conversion member according to the first embodiment of the present disclosure. FIG. 2 is a flowchart illustrating a process sequence of a method for manufacturing a wavelength conversion member according to the second embodiment of the present disclosure. FIG. 3 is a cross-sectional SEM photograph of the wavelength conversion member according to the first embodiment. FIG. 4 is a cross-sectional SEM photograph of the wavelength conversion member according to Example 11. FIG. 5 is an external photograph of the wavelength conversion member according to the first embodiment. FIG. 6 is a cross-sectional SEM photograph of the wavelength conversion member according to Example 21. FIG. 7 is a cross-sectional SEM photograph of the wavelength conversion member according to Comparative Example 31. FIG. 8 is an external photograph of the wavelength conversion member according to Comparative Example 31. FIG. 9 is an external photograph of the wavelength conversion member according to Example 32. FIG. 10 is an external photograph of the wavelength conversion member according to Example 21. FIG. 11 is an appearance photograph of the wavelength conversion member according to Example 34.

  Hereinafter, a method for manufacturing a wavelength conversion member according to the present invention will be described based on embodiments. However, the embodiments described below are examples for embodying the technical idea of the present invention, and the present invention is not limited to the following method for manufacturing a wavelength conversion member. The relationship between the color name and the chromaticity coordinates, the relationship between the light wavelength range and the color name of the monochromatic light, and the like conform to JIS Z8110.

Method for Manufacturing Wavelength Conversion Member According to First Embodiment A method for manufacturing a wavelength conversion member according to the first embodiment includes an yttrium aluminum garnet-based phosphor having a composition represented by the following formula (I), and alumina purity. Preparing a compact containing 99.0% by mass or more of alumina particles, primary sintering of the compact to obtain a first sintered body, hot working of the first sintered body, etc. Secondary sintering by a hot pressing (HIP) process to obtain a second sintered body.
Hereinafter, the yttrium aluminum garnet-based phosphor may also be referred to as “YAG-based phosphor”.
_{(Y 1-a-b Gd} a Ce b) 3 Al 5 O 12 (I)
Here, in the formula (I), a and b are numbers satisfying 0 ≦ a ≦ 0.3 and 0 <b ≦ 0.022.

  In the phosphor having the composition represented by the formula (I), the variable a is the activation amount of Gd, and the variable a is 0 or more and 0.3 or less (0 ≦ a ≦ 0.3), preferably 0 or less. 0.01 to 0.28 (0.01 ≦ a ≦ 0.28), more preferably 0.02 to 0.27 (0.02 ≦ b ≦ 0.27), even more preferably 0.03 to 0 .25 or less (0.03 ≦ a ≦ 0.25), and even more preferably 0.05 or more and 0.25 or less (0.05 ≦ a ≦ 0.25). In the phosphor having the composition represented by the formula (I), Gd may not be included in the crystal structure. In the phosphor having the composition represented by the formula (I), when the variable a, which is the activation amount of Gd, exceeds 0.3, the emission peak wavelength of the phosphor shifts, and a desired light conversion efficiency cannot be obtained. There are cases.

  In the YAG-based phosphor having the composition represented by the formula (I), the variable b is the activation amount of Ce, and the variable b is more than 0 and equal to or less than 0.022 (0 <b ≦ 0.022). It is preferably 0.0001 or more and 0.020 or less (0.0001 ≦ b ≦ 0.02), and more preferably 0.0002 or more and 0.015 or less (0.0002 ≦ b ≦ 0.015). And still more preferably 0.0002 or more and 0.012 or less (0.0002 ≦ b ≦ 0.012), and still more preferably 0.0003 or more and 0.012 or less (0.0003 ≦ b ≦ 0.012). In the phosphor having the composition represented by the formula (I), when the value of the variable b, which is the amount of activation of Ce, is 0, the element serving as the luminescence center does not exist in the crystal structure and does not emit light. When the value of the variable b exceeds 0.022, the light emission intensity tends to decrease due to concentration quenching, and a desired light conversion efficiency cannot be obtained.

  The average particle size of the YAG phosphor particles is preferably in the range of 1 μm to 50 μm, more preferably in the range of 1 μm to 40 μm, still more preferably in the range of 2 μm to 40 μm, and still more preferably 2 μm. The range is at least 20 μm and particularly preferably at least 2 μm and at most 15 μm. When the average particle size of the YAG-based phosphor particles is 1 μm or more, the YAG-based phosphor particles can be substantially uniformly dispersed in the molded body. When the average particle diameter of the YAG-based phosphor is 50 μm or less, the voids in the wavelength conversion member are reduced, so that the light conversion efficiency can be increased. In this specification, the average particle size of the phosphor is defined as an average particle size (Fisher sub-sieve sizer's number) measured by a Fisher sub-sieve sizer (hereinafter also referred to as “FSSS method”). Say.

  The content of the YAG-based phosphor is preferably 0.1% by mass or more and 99.9% by mass or less, more preferably 0.5% by mass or more, based on 100% by mass of the total amount of the YAG-based phosphor and the alumina particles. 99% by mass or less, more preferably 1% by mass or more and 95% by mass or less, still more preferably 2% by mass or more and 80% by mass or less, still more preferably 3% by mass or more and 70% by mass or less, still more preferably 3% by mass or less. It is at least 50% by mass, more preferably at least 4% by mass and at most 50% by mass, particularly preferably at least 5% by mass and at most 50% by mass.

The alumina particles contained in the powder constituting the compact have an alumina purity of 99.0% by mass or more, more preferably 99.5% by mass or more. When the powder constituting the molded body contains alumina particles having an alumina purity of 99.0% by mass or more, the light conversion efficiency can be increased, and a wavelength conversion member having good thermal conductivity can be obtained. it can. When using commercially available alumina particles, the catalog value can be referred to for the alumina purity. If the alumina purity is unknown, after measuring the mass of the alumina particles, each alumina particle is fired at 800 ° C. for 1 hour in an air atmosphere, and the organic components and the alumina particles adhering to the alumina particles absorb moisture. By removing the water content, measuring the mass of the alumina particles after firing, and dividing the mass of the alumina particles after firing by the mass of the alumina particles before firing, the alumina purity can be measured. The alumina purity can be calculated, for example, by the following equation.
Alumina purity (% by mass) = (mass of alumina particles after firing / mass of alumina particles before firing) × 100

  The average particle diameter of the alumina particles is preferably in the range of 0.2 μm to 1.3 μm, more preferably in the range of 0.2 μm to 1.0 μm, and still more preferably 0.3 μm to 0.8 μm. The range is as follows, and more preferably the range is 0.3 μm or more and 0.6 μm or less. When the average particle size of the alumina particles is in the above range, the YAG-based phosphor powder and the alumina particles can be uniformly mixed, and the wavelength conversion member formed of a sintered body having a small amount of voids and a high density can be manufactured. it can. In the present specification, the average particle size of the alumina particles refers to a particle size (median size) at which the volume accumulation frequency from the small diameter side reaches 50% as measured by a laser diffraction scattering type particle size distribution measuring method.

  The content of the alumina particles having an alumina purity of 99.0% by mass or more is preferably 0.1% by mass or more and 99.9% by mass or less, more preferably 100% by mass or more with respect to the total amount of the YAG phosphor and the alumina particles of 100% by mass. Is from 1% by mass to 99.5% by mass, more preferably from 5% by mass to 99% by mass, still more preferably from 20% by mass to 98% by mass, still more preferably from 30% by mass to 97% by mass, It is even more preferably 50% by mass to 97% by mass, still more preferably 50% by mass to 96% by mass, and particularly preferably 50% by mass to 95% by mass.

The powder constituting the molded body transmits light from the light emitting element without hindering the conversion of light by the YAG-based phosphor particles, in addition to the YAG-based phosphor particles and alumina particles having an alumina purity of 99.0% by mass or more. May be contained. The powder other than the YAG phosphor particles and the alumina particles having an alumina purity of 99.0% by mass or more that constitute the molded body is preferably a powder having a relatively high thermal conductivity. Thereby, the heat applied to the YAG-based phosphor particles can be easily released to the outside, and the heat radiation of the wavelength conversion member can be improved. The powder which transmits light from the light emitting _{element, MgO, LiF, Nb 2 O} 5, NiO, powder containing at least one of SiO 2, TiO ₂ or _Y 2 _{O 3} and the like. As the powder that transmits light from the light-emitting element, a powder having a crystal structure including two or more types selected from the group consisting of MgO, LiF, SiO ₂ , TiO _2, and Y ₂ O ₃ may be used.
In the case where the powder constituting the molded body contains a powder other than the YAG phosphor and alumina particles having an alumina purity of 99.0% by mass or more (hereinafter, also referred to as “other powders”), the other is used. The total amount of the powder and the alumina particles is 99.9% by mass or less, more preferably 98.0% by mass or less, still more preferably 95.0% by mass or less, in 100% by mass of the powder constituting the compact. It is still more preferably 90.0% by mass or less, preferably 0.1% by mass or more, more preferably 1.0% by mass or more. The mixing ratio of alumina particles to other powder (alumina particles: other powder) is preferably 1:99 to 99: 1, more preferably 10:90 to 90:10.

  FIG. 1 is a flowchart illustrating an example of a process sequence of a method for manufacturing a wavelength conversion member according to the first embodiment. The steps of the method for manufacturing a wavelength conversion member will be described with reference to FIG. The method for manufacturing the wavelength conversion member includes a molded body preparing step S102, a primary firing step S103, and a secondary firing step S104. The method for manufacturing a wavelength conversion member may include a powder mixing step S101 before the compact preparing step S102, and includes a processing step S105 for processing the wavelength conversion member after the secondary firing step S104. Is also good.

Powder mixing step In the powder mixing step, the powder constituting the compact is mixed. The powder constituting the compact includes YAG-based phosphor particles and alumina particles having an alumina purity of 99.0% by mass or more. The powder can be mixed using a mortar and pestle. The powder may be mixed using a mixing medium such as a ball mill. Also, a small amount of a molding aid such as water or ethanol may be used to facilitate mixing of the powder and further facilitate molding of the powder after mixing. The molding aid is preferably one that is easily volatilized in the subsequent firing step. When the molding aid is added, the molding aid is preferably 10% by mass or less based on 100% by mass of the powder. , More preferably 8% by mass or less, and even more preferably 5% by mass or less.

Molded Body Preparing Step In the molded body preparing step, a powder containing the YAG-based phosphor is molded into a desired shape to obtain a molded body. A known method such as a press molding method can be used as a method of molding the powder. For example, a die press molding method, a cold isostatic pressing method (CIP: Cold Isostatic Pressing, hereinafter, also referred to as “CIP”). ). As the molding method, two types of methods may be employed in order to adjust the shape of the molded body, and CIP may be performed after performing die press molding. In the case of CIP, it is preferable to press the formed body by a cold isostatic pressing method using water as a medium.

  The pressure at the time of die press molding is preferably from 5 MPa to 50 MPa, more preferably from 5 MPa to 20 MPa. When the pressure at the time of die press molding is in the above range, the molded body can be adjusted to a desired shape.

  The pressure in the CIP treatment is preferably from 50 MPa to 200 MPa, more preferably from 50 MPa to 180 MPa. When the pressure in the CIP treatment is within the above range, the density of the molded body can be increased, and a molded body having a substantially uniform density can be obtained as a whole, and the sintered body obtained in the subsequent primary firing step and secondary firing step can be obtained. Increases body density.

Primary firing step The primary firing step is a step of first firing the molded body to obtain a first sintered body. In the primary firing step, by increasing the sintering density of the YAG-based phosphor particles contained in the molded body or between the YAG-based phosphor particles and other powders, the secondary firing after the primary firing further reduces the sintered body. Density can be increased.

  The primary firing is preferably performed in an oxygen-containing atmosphere. The oxygen-containing atmosphere is an atmosphere containing at least oxygen, and the concentration of oxygen contained in the atmosphere may be 5% by volume or more, preferably 10% by volume or more, and more preferably 15% by volume or more. The oxygen-containing atmosphere in which the primary firing is performed is preferably air (oxygen concentration is about 20% by volume). By performing the primary firing of the molded body in an oxygen-containing atmosphere, the blackening of the molded body, which is considered to be caused by the deterioration of the YAG-based phosphor particles due to the firing, can be restored.

  The primary firing temperature is preferably in the range of 1200 ° C. to 1800 ° C., more preferably in the range of 1500 ° C. to 1800 ° C., and even more preferably in the range of 1600 ° C. to 1780 ° C. When the temperature of the primary firing is 1200 ° C. or higher, the sintered density of the sintered body can be increased, and in the secondary firing after the primary firing, the density of the second sintered body can be further increased. When the temperature of one firing is 1800 ° C. or less, a sintered body can be formed without dissolving the molded body.

Secondary firing step In the secondary firing step, the first sintered body is subjected to hot isostatic pressing (HIP) processing (hereinafter, also referred to as “HIP processing”) to form the second sintered body. This is the step of obtaining In the secondary firing step, the HIP treatment can reduce the voids contained in the first sintered body and increase the density of the second sintered body.

  The secondary firing is preferably performed in an inert gas atmosphere. Since the secondary firing is performed by the HIP process, the pressure medium for performing the HIP process is preferably in an inert gas atmosphere. The inert gas atmosphere means an atmosphere containing argon, helium, nitrogen, or the like as a main component in the atmosphere. Here, that argon, helium, nitrogen, or the like is the main component in the atmosphere means that the atmosphere contains at least one gas selected from the group consisting of argon, helium, and nitrogen in an amount of 50% by volume or more. The concentration of oxygen in the inert gas atmosphere is preferably 3% by volume or less, more preferably 1% by volume or less.

  The pressure in the HIP treatment for performing the secondary firing is preferably from 50 MPa to 300 MPa, more preferably from 80 MPa to 200 MPa. When the pressure in the HIP treatment is within the above range, the entire sintered body can be uniformly and at a higher density without destroying the crystal structure of the YAG-based phosphor particles.

  The temperature of the secondary firing is preferably in the range of 1500 ° C to 1800 ° C, more preferably in the range of 1600 ° C to 1780 ° C, and even more preferably in the range of 1600 ° C to 1770 ° C. When the secondary firing temperature is 1500 ° C. or higher, the sintered density of the sintered body can be increased. If the secondary firing temperature is 1800 ° C. or lower, a sintered body can be formed without melting the sintered body.

Processing Step The manufacturing method of the wavelength conversion member may include a processing step of processing the obtained wavelength conversion member. The processing step includes a step of cutting the obtained wavelength conversion member into a desired size. As a method for cutting the wavelength conversion member, a known method can be used, and examples thereof include blade dicing, laser dicing, and a wire saw. Among them, a wire saw is preferable because the cut surface is flattened with high precision. Through the processing step, a wavelength conversion member having a desired thickness and size can be obtained. The thickness of the wavelength conversion member is not particularly limited, but is preferably in the range of 1 μm to 1 mm, more preferably 10 μm to 800 μm, still more preferably 50 μm to 500 μm, in consideration of mechanical strength and wavelength conversion efficiency. More preferably, it is in the range of 100 μm or more and 300 μm or less.

Method for Producing Wavelength Conversion Member According to Second Embodiment A method for producing a wavelength conversion member according to a second embodiment of the present invention is directed to a molding method including a YAG-based phosphor and alumina particles having an alumina purity of 99.0% by mass or more. Preparing a body, first firing the molded body to obtain a first sintered body, and second firing the first sintered body by hot isostatic pressing (HIP) processing; Obtaining a second sintered body and annealing the second sintered body in an oxygen-containing atmosphere.

  FIG. 2 is a flowchart illustrating an example of a process sequence of a method for manufacturing a wavelength conversion member according to the second embodiment. With reference to FIG. 2, steps of a method for manufacturing a wavelength conversion member will be described. The method for manufacturing the wavelength conversion member includes a compact preparing step S202, a primary firing step S203, a secondary firing step S204, and an annealing step S205. The method for manufacturing the wavelength conversion member may include a powder mixing step S201 before the molded body preparing step S202, and may include a processing step S206 for processing the wavelength conversion member after the annealing step S205. .

As the YAG-based phosphor, a YAG-based phosphor represented by Y ₃ Al ₅ O ₁₂ : Ce and a YAG-based phosphor represented by (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ : Ce are used. You may. The YAG-based phosphor also includes a YAG-based phosphor having a composition represented by the formula (I). The YAG-based phosphor represented by Y ₃ Al ₅ O ₁₂ : Ce may have a composition in which at least a part of yttrium is replaced by an element such as terbium (Tb) or lutetium (Lu). The content of the YAG-based phosphor particles in the powder constituting the compact may be in the same range as the content of the YAG-based phosphor in the production method of the first embodiment.
Further, as the alumina particles having an alumina purity of 99.0% by mass or more, the same particles as in the production method of the first embodiment can be used. The content of the alumina particles in the powder constituting the compact may be in the same range as the content of the alumina particles in the production method of the first embodiment.

  In the method for manufacturing the wavelength conversion member according to the second embodiment, the green body preparation step, the primary firing step, and the secondary firing step are the same as the method for manufacturing the wavelength conversion member according to the first embodiment. Good. Also in the method for manufacturing the wavelength conversion member according to the second embodiment, in the green body preparation step, similarly to the preparation step for the green body in the method for manufacturing the wavelength conversion member according to the first embodiment, YAG-based phosphor particles are used. In addition to the alumina particles having an alumina purity of 99.0% by mass or more, a powder that transmits light from the light emitting element without hindering the conversion of light by the YAG-based phosphor particles may be included.

Annealing Step The method for manufacturing a wavelength conversion member according to the second embodiment includes an annealing step. The annealing step is a step of annealing the second sintered body in an oxygen-containing atmosphere to obtain a wavelength conversion member. In the secondary firing step, while a second sintered body having an increased density is obtained, the second sintered body may be colored black. This is considered to be one of the causes of a change in the composition ratio of oxygen, which is one of the constituent elements of the YAG-based phosphor composition, in the secondary firing step. Therefore, when the second sintered body is colored black after the secondary firing step, the YAG-based material is subjected to the annealing step without lowering the density of the sintered body increased in the secondary firing step. The original color of the phosphor can be restored. After the annealing step, the wavelength conversion member is generally bright and has the original body color of the YAG-based phosphor, and there are few black regions that absorb light, so that the light conversion efficiency can be increased.

  Annealing is performed in an oxygen-containing atmosphere. The oxygen-containing atmosphere is an atmosphere containing at least oxygen, and the concentration of oxygen contained in the atmosphere may be 5% by volume or more, preferably 10% by volume or more, and more preferably 15% by volume or more. Annealing is preferably performed in an atmosphere (at an oxygen concentration of about 20% by volume).

  The annealing temperature is preferably in the range of 1200 ° C. to 1700 ° C., more preferably 1570 ° C. to 1700 ° C., and even more preferably 1580 ° C. to 1630 ° C. If the annealing temperature is 1200 ° C. or more, the dark and dark color of the second sintered body can be returned to the original body color of the YAG phosphor without lowering the density of the second sintered body. it can. When the annealing temperature is 1700 ° C. or lower, the crystal structure of the second sintered body can be maintained, and the dark and dark color of the second sintered body can be returned to the original body color of the YAG-based phosphor.

  The method of manufacturing the wavelength conversion member according to the second embodiment may include a processing step of processing the obtained wavelength conversion member, as in the method of manufacturing the wavelength conversion member according to the first embodiment. For the processing step, the same method as the processing step in the method for manufacturing the wavelength conversion member according to the first embodiment can be used.

Relative Density of First Sintered Body In the method for manufacturing the wavelength conversion member of the first and second embodiments, the first sintered body obtained in the primary firing step has a relative density of preferably 95% or more. And more preferably 96% or more. When the relative density of the first sintered body is 95% or more, the density of the second sintered body can be further increased in the secondary firing after the primary firing, and the gap of the wavelength conversion member is reduced, Since the scattering of light in the gap is suppressed, a wavelength conversion member having high light conversion efficiency can be manufactured.

In this specification, the relative density of the first sintered body refers to a value calculated by an apparent density of the first sintered body with respect to a true density of the first sintered body. The relative density is calculated by the following equation (1).
Relative density (%) = (apparent density of first sintered body ÷ true density of first sintered body) × 100 (1)
The true density of the first sintered body is a value obtained by multiplying the mass ratio of the YAG-based phosphor to the total amount of the YAG-based phosphor, alumina particles and other powders by the true density of the YAG-based phosphor. And the value obtained by multiplying the mass ratio of the alumina particles and the other powder by the true density of the alumina particles and the other powder. When the first sintered body contains the YAG-based phosphor and the alumina particles, and does not contain other powders, the mass ratio of the alumina particles to the mass ratio of the alumina particles to the total amount of the YAG-based phosphor and the alumina particles is used. It means the sum of the value obtained by multiplying the true density and the value obtained by multiplying the mass ratio of the YAG-based phosphor by the true density of the YAG-based phosphor. For example, the true density of the first sintered body is calculated by the following equation (2).
True density of first sintered body = (mass ratio of YAG-based phosphor to total amount of YAG-based phosphor and alumina particles × true density of YAG-based phosphor) + (total amount of YAG-based phosphor and alumina particles) (Mass ratio of alumina particles with respect to the actual density of alumina particles) (2)
The apparent density of the first sintered body is a value obtained by dividing the mass of the first sintered body by the volume of the first sintered body obtained by the Archimedes method. The apparent density of the first sintered body is calculated by the following equation (3).
Apparent density of first sintered body = mass of first sintered body / volume of first sintered body determined by Archimedes method (3)

Relative Density of Wavelength Conversion Member In the method for manufacturing the wavelength conversion member according to the first and second embodiments, the wavelength conversion member obtained after the secondary firing or after the annealing preferably has a relative density of 97% or more. When the relative density of the wavelength conversion member is 97% or more, the gap of the wavelength conversion member is reduced, and the light conversion efficiency can be increased. Further, since the wavelength conversion member having a relative density of 97% or more after the secondary firing or the annealing is obtained, for example, in the processing step, the wavelength conversion member can be easily processed without chipping even if processing is performed. Become.

In this specification, the relative density of the wavelength conversion member refers to a value calculated by an apparent density of the wavelength conversion member with respect to a true density of the wavelength conversion member. The relative density is calculated by the following equation (4).
Relative density (%) = (apparent density of wavelength conversion member / true density of wavelength conversion member) × 100 (4)
The method of calculating the true density of the wavelength conversion member is calculated in the same manner as the true density of the first sintered body. The true density of the wavelength conversion member is the same value as the true density of the first sintered body.
The apparent density of the wavelength conversion member is a value obtained by dividing the mass of the wavelength conversion member by the volume of the wavelength conversion member obtained by the Archimedes method. The apparent density of the wavelength conversion member is calculated by the following equation (5).
Apparent density of wavelength conversion member = mass of wavelength conversion member / volume determined by Archimedes method of wavelength conversion member (5)

  In the wavelength conversion member obtained by the manufacturing method of the present embodiment, the wavelength conversion member has a high density, the relative emission intensity can be increased, and the light conversion efficiency can be increased.

  The wavelength conversion member is composed of a matrix of molten alumina, in which YAG-based phosphor particles that are distinguished from the alumina matrix by grain boundaries are present, and the alumina particles and the YAG-based phosphor are integrated to convert the wavelength of ceramics. Configure the members. In the first embodiment and the second embodiment, in the green body preparation step before the primary firing, the raw material constituting the YAG-based phosphor and the alumina particles are not mixed to form a green body, but the YAG-based fluorescent material is used. The body and alumina particles are mixed to form a molded body, which is subjected to primary firing and secondary firing to obtain a wavelength conversion member. Observation of the cross-sectional photograph of the wavelength conversion member shows that YAG-based phosphor particles, which are distinguished from the matrix by the grain boundaries, are scattered in the matrix composed of alumina, which is formed by melting and integrating alumina particles. Can be confirmed. When the YAG-based phosphor particles are substantially uniformly dispersed in the matrix made of alumina and the relative density of the wavelength conversion member is 97% or more, the wavelength conversion member made of ceramics is processed by cutting or the like. Even when the wavelength conversion member is used for a light emitting device, generation of color unevenness can be suppressed without causing cracks or chipping.

The wavelength conversion member obtained by the manufacturing method of the first embodiment or the manufacturing method of the second embodiment, by combining with a light emitting element, converts light emitted from the light emitting element, and the light from the light emitting element It is possible to configure a light emitting device that emits mixed color light whose wavelength is converted by the wavelength conversion member. As the light-emitting element, for example, a light-emitting element which emits light in a wavelength range of 350 nm to 500 nm can be used. As the light-emitting element, for example, a semiconductor light-emitting element using a nitride-based semiconductor (In _X Al _Y Ga _1-XY N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) can be used. By using a semiconductor light emitting element as an excitation light source, it is possible to obtain a stable light emitting device with high efficiency, high output linearity with respect to input, and strong mechanical shock.

  Hereinafter, the present invention will be described specifically with reference to examples. The present invention is not limited to these examples.

Production Example of YAG Phosphor Yttrium oxide (Y ₂ O ₃ ), gadolinium oxide (Gd ₂ O ₃ ), cerium oxide (CeO ₂ ), and aluminum oxide (Al ₂ O ₃ ) The resulting mixture was weighed to obtain a raw material mixture, barium fluoride (BaF ₂ ) was added as a flux, and the raw material mixture and the flux were mixed by a ball mill. This mixture was put into an alumina crucible and fired in a reducing atmosphere at a temperature in the range of 1400 ° C. to 1600 ° C. for 10 hours to obtain a fired product. The obtained calcined product is dispersed in pure water, a solvent stream is applied while applying various vibrations through a sieve, passed through a wet sieve, then dehydrated, dried, and classified by passing through a dry sieve. Each phosphor having a desired composition and used in Examples 1 to 19 and Comparative Examples 1 to 4 was prepared. The composition and average particle size of each phosphor were measured by the following methods. Table 1 shows the results.

Average Particle Size The obtained phosphor has a volume accumulation frequency from the small diameter side of 50% as measured by a laser diffraction particle size distribution analyzer (product name: MASTER Sizer 3000, manufactured by MALVERN). The volume average particle diameter (median diameter) reached was defined as the average particle diameter.

Composition analysis The obtained phosphor was analyzed by ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometer) (product name: Perkin Elmer) to remove each element (Y, Gd, Ce, Al, O) were measured for the mass percentage (% by mass), and the molar ratio of each element was calculated from the value of the mass percentage of each element. The molar ratio of Gd (variable a) and the molar ratio of Ce (variable b) shown in Table 1 are values calculated on the assumption that the measured molar ratio of Al is 5, and the molar ratio of Al is 5 as a reference.

Example 1
25 parts by mass of a YAG-based phosphor represented by (Y _0.921 Gd _0.070 Ce _0.009 ) ₃ Al ₅ O ₁₂ having an average particle size of 5 μm obtained by a production example of the YAG-based phosphor, 75 parts by mass of α-alumina particles having a particle size of 0.40 μm (product name: AHP200, manufactured by Nippon Light Metal Co., Ltd., alumina purity: 99.5% by mass) are weighed and mixed by a dry ball mill to obtain a mixed powder for a compact. Got ready. The alumina purity of the α-alumina particles was measured by the same method as the method for measuring the alumina purity described below. After removing the balls used as the mixing medium from the mixed powder, the mixed powder was filled in a mold, and a cylindrical molded body having a diameter of 20 mm and a thickness of 20 mm was formed at a pressure of 19.6 MPa (200 kgf / cm ² ). Formed. The obtained molded body was placed in a packaging container, vacuum-packaged, and subjected to a CIP treatment at 176 MPa by a cold isostatic pressing device (manufactured by KOBELCO). The obtained molded body is held in a firing furnace (manufactured by Marusho Denki KK) in an air atmosphere (oxygen concentration: about 20% by volume) at a temperature of 1700 ° C. for 6 hours to perform primary sintering, thereby performing first sintering. I got a body. The obtained first sintered body was heated at 1750 ° C. and 198 MPa using a HIP apparatus (manufactured by KOBELCO) under a nitrogen gas atmosphere (nitrogen: 99% by volume or more) using nitrogen gas as a pressure medium. Second firing was performed by HIP treatment for 2 hours to obtain a second sintered body, which was used as a wavelength conversion member.

Example 2
A wavelength conversion member was obtained in the same manner as in Example 1 except that a mixed powder in which 40 parts by mass of a YAG-based phosphor and 60 parts by mass of α-alumina particles were mixed was prepared.

Example 3
A wavelength conversion member was obtained in the same manner as in Example 1 except that a mixed powder in which 50 parts by mass of a YAG-based phosphor and 50 parts by mass of α-alumina particles were mixed was prepared.

Example 4
15 parts by mass of the YAG-based phosphor represented by (Y _0.862 Gd _0.130 Ce _0.008 ) ₃ Al ₅ O ₁₂ having an average particle size of 5 μm obtained by the production example of the YAG-based phosphor, 85 parts by mass of α-alumina particles having a particle size of 0.40 μm (product name: AHP200, manufactured by Nippon Light Metal Co., Ltd., alumina purity: 99.5% by mass) were weighed and mixed by a dry ball mill to obtain a mixed powder for a compact. Was prepared. After removing the balls used as the mixing medium from the mixed powder, the mixed powder was filled in a mold, and a cylindrical molded body having a diameter of 20 mm and a thickness of 20 mm was formed at a pressure of 19.6 MPa (200 kgf / cm ² ). Formed. The obtained molded body was placed in a packaging container, vacuum-packaged, and subjected to a CIP treatment at 176 MPa by a cold isostatic pressing device (manufactured by KOBELCO). The obtained molded body is held in a firing furnace (manufactured by Marusho Denki KK) in an air atmosphere (oxygen concentration: about 20% by volume) at a temperature of 1700 ° C. for 6 hours to perform primary sintering, thereby performing first sintering. I got a body.
The obtained first sintered body was heated at 1750 ° C. and 198 MPa using a HIP apparatus (manufactured by KOBELCO) under a nitrogen gas atmosphere (nitrogen: 99% by volume or more) using nitrogen gas as a pressure medium. Second firing was performed by HIP treatment for 2 hours to obtain a second sintered body, which was used as a wavelength conversion member.

Example 5
A wavelength conversion member was obtained in the same manner as in Example 4, except that a mixed powder was prepared by mixing 20 parts by mass of a YAG-based phosphor and 80 parts by mass of α-alumina particles.

Example 6
25 parts by mass of a YAG-based phosphor represented by (Y _0.746 Gd _0.250 Ce _0.004 ) ₃ Al ₅ O ₁₂ having an average particle size of 5 μm obtained by a production example of the YAG-based phosphor, 75 parts by mass of α-alumina particles having a particle size of 0.40 μm (product name: AHP200, manufactured by Nippon Light Metal Co., Ltd., alumina purity: 99.5% by mass) are weighed and mixed by a dry ball mill to obtain a mixed powder for a compact. Was prepared. After removing the balls used as the mixing medium from the mixed powder, the mixed powder was filled in a mold, and a cylindrical molded body having a diameter of 20 mm and a thickness of 20 mm was formed at a pressure of 19.6 MPa (200 kgf / cm ² ). Formed. The obtained molded body was placed in a packaging container, vacuum-packaged, and subjected to a CIP treatment at 176 MPa by a cold isostatic pressing device (manufactured by KOBELCO). The obtained molded body is held in a firing furnace (manufactured by Marusho Denki KK) in an air atmosphere (oxygen concentration: about 20% by volume) at a temperature of 1700 ° C. for 6 hours to perform primary sintering, thereby performing first sintering. I got a body.
The obtained first sintered body was heated at 1750 ° C. and 198 MPa using a HIP apparatus (manufactured by KOBELCO) under a nitrogen gas atmosphere (nitrogen: 99% by volume or more) using nitrogen gas as a pressure medium. Secondary baking was performed by HIP treatment for 2 hours to obtain a second sintered body, and this second sintered body was used as a wavelength conversion member.

Example 7
Except that a YAG-based phosphor represented by (Y _0.927 Gd _0.070 Ce _0.003 ) ₃ Al ₅ O ₁₂ having an average particle size of 5 μm obtained by a production example of the YAG-based phosphor was used. A wavelength conversion member was obtained in the same manner as in Example 6.

Example 8
_Except that a YAG-based phosphor represented by (Y _0.897 Gd _0.100 Ce _0.003 ) ₃ Al ₅ O ₁₂ having an average particle size of 5 μm obtained by a production example of the YAG-based phosphor was used. A wavelength conversion member was obtained in the same manner as in Example 6.

Example 9
_Except that a YAG-based phosphor represented by (Y _0.867 Gd _0.130 Ce _0.003 ) ₃ Al ₅ O ₁₂ having an average particle diameter of 5 μm obtained by a production example of the YAG-based phosphor was used. A wavelength conversion member was obtained in the same manner as in Example 6.

Example 10
Except that a YAG-based phosphor represented by (Y _0.797 Gd _0.200 Ce _0.003 ) ₃ Al ₅ O ₁₂ having an average particle size of 5 μm obtained by a production example of the YAG-based phosphor was used. A wavelength conversion member was obtained in the same manner as in Example 6.

Example 11
25 parts by mass of a YAG-based phosphor represented by (Y _0.922 Gd _0.070 Ce _0.008 ) ₃ Al ₅ O ₁₂ having an average particle diameter of 12 μm obtained by a production example of the YAG-based phosphor, 75 parts by mass of α-alumina particles having a particle size of 0.40 μm (product name: AHP200, manufactured by Nippon Light Metal Co., Ltd., alumina purity: 99.5% by mass) are weighed and mixed by a dry ball mill to obtain a mixed powder for a compact. Was prepared. After removing the balls used as the mixing medium from the mixed powder, the mixed powder is filled in a mold to form a cylindrical molded body having a diameter of 20 mm and a thickness of 20 mm at a pressure of 19.6 MPa (200 kgf / cm ² ). did. The obtained molded body was placed in a packaging container, vacuum-packaged, and subjected to a CIP treatment at 176 MPa by a cold isostatic pressing device (manufactured by KOBELCO). The obtained molded body is held in a firing furnace (manufactured by Marusho Denki KK) in an air atmosphere (oxygen concentration: about 20% by volume) at a temperature of 1700 ° C. for 6 hours to perform primary sintering, thereby performing first sintering. I got a body.
The obtained first sintered body was heated at 1750 ° C. and 198 MPa using a HIP apparatus (manufactured by KOBELCO) under a nitrogen gas atmosphere (nitrogen: 99% by volume or more) using nitrogen gas as a pressure medium. Second firing was performed by HIP treatment for 2 hours to obtain a second sintered body, which was used as a wavelength conversion member.

Example 12
A wavelength conversion member was obtained in the same manner as in Example 11, except that a mixed powder using 30 parts by mass of a YAG-based phosphor and 70 parts by mass of α-alumina particles was prepared.

Example 13
A wavelength conversion member was obtained in the same manner as in Example 11, except that a mixed powder was prepared using 40 parts by mass of a YAG-based phosphor and 60 parts by mass of α-alumina particles.

Example 14
A wavelength conversion member was obtained in the same manner as in Example 11, except that a mixed powder using 50 parts by mass of a YAG-based phosphor and 50 parts by mass of α-alumina particles was prepared.

Example 15
Except that a YAG-based phosphor represented by (Y _0.921 Gd _0.070 Ce _0.009 ) ₃ Al ₅ O ₁₂ having an average particle diameter of 12 μm obtained in the production example of the YAG-based phosphor was used. In the same manner as in Example 11, a wavelength conversion material was obtained.

Example 16
A wavelength conversion member was obtained in the same manner as in Example 11, except that a mixed powder using 5 parts by mass of a YAG-based phosphor and 95 parts by mass of α-alumina particles was prepared.

Example 17
A wavelength conversion member was obtained in the same manner as in Example 11, except that a mixed powder using 7 parts by mass of a YAG-based phosphor and 93 parts by mass of α-alumina particles was prepared.

Example 18
A wavelength conversion member was obtained in the same manner as in Example 11, except that a mixed powder using 9 parts by mass of a YAG-based phosphor and 91 parts by mass of α-alumina particles was prepared.

Example 19
A wavelength conversion member was obtained in the same manner as in Example 11, except that a mixed powder using 15 parts by mass of a YAG-based phosphor and 85 parts by mass of α-alumina particles was prepared.

Comparative Example 1
7 parts by mass of a YAG phosphor represented by (Y _0.976 Ce _0.024 ) ₃ Al ₅ O ₁₂ having an average particle size of 5 μm, and α-alumina particles having an average particle size of 0.40 μm (product name: AHP200, Nippon Light Metal) 93 parts by mass (alumina purity: 99.5% by mass, manufactured by Co., Ltd.) were weighed and mixed by a dry ball mill to prepare a mixed powder for a compact. After removing the balls used as the mixing medium from the mixed powder, the mixed powder was filled in a mold, and a cylindrical molded body having a diameter of 20 mm and a thickness of 20 mm was formed at a pressure of 19.6 MPa (200 kgf / cm ² ). Formed. The obtained molded body was placed in a packaging container, vacuum-packaged, and subjected to a CIP treatment at 176 MPa by a cold isostatic pressing device (manufactured by KOBELCO). The obtained molded body is held in a firing furnace (manufactured by Marusho Denki KK) in an air atmosphere (oxygen concentration: about 20% by volume) at a temperature of 1700 ° C. for 6 hours to perform primary sintering, thereby performing first sintering. I got a body.
The obtained first sintered body was heated at 1750 ° C. and 198 MPa using a HIP apparatus (manufactured by KOBELCO) under a nitrogen gas atmosphere (nitrogen: 99% by volume or more) using nitrogen gas as a pressure medium. Second firing was performed by HIP treatment for 2 hours to obtain a second sintered body, which was used as a wavelength conversion member.

Comparative Example 2
A wavelength conversion member was obtained in the same manner as in Comparative Example 1, except that a mixed powder using 11 parts by mass of a YAG-based phosphor and 89 parts by mass of α-alumina particles was prepared.

Comparative Example 3
A wavelength conversion member was obtained in the same manner as in Comparative Example 1, except that a mixed powder using 15 parts by mass of a YAG-based phosphor and 85 parts by mass of α-alumina particles was prepared.

Comparative Example 4
A wavelength conversion member was obtained in the same manner as in Comparative Example 1, except that a mixed powder using 20 parts by mass of a YAG-based phosphor and 80 parts by mass of α-alumina particles was prepared.

Measurement of Relative Density of First Sintered Body In Examples 1 to 19 and Comparative Examples 1 to 4, the relative density of each first sintered body was measured. Table 1 shows the results.
The relative density was calculated by the following equation (1).
Relative density (%) = (apparent density of first sintered body ÷ true density of first sintered body) × 100 (1)

The true density of the first sintered body was calculated from the following equation (2). The true density of the α-alumina particles used in Examples and Comparative Examples was 3.98 g / cm ^3, and Examples 1-3, Example 7, and Examples 11-19 were 4.69 g / cm ³ , Examples 4- 5, example 9 4.77 g / cm ^3, example 6 4.92 g / cm ^3, example 8 4.73 g / cm ^3, example 10 4.86 g / cm ^3, Comparative example 1 4 was calculated as 4.60 g / cm ³ .
True density of first sintered body = (mass ratio of YAG-based phosphor to total amount of YAG-based phosphor and alumina particles × true density of YAG-based phosphor) + (total amount of YAG-based phosphor and alumina particles) (Mass ratio of alumina particles with respect to the actual density of alumina particles) (2)

The apparent density of the first sintered body was calculated by the following equation (3).
Apparent density of first sintered body = mass of first sintered body / volume of first sintered body determined by Archimedes method (3)

Measurement of relative density of wavelength conversion member The relative density of the wavelength conversion members of Examples 1 to 19 and Comparative Examples 1 to 4 was measured. Table 1 shows the results.
The relative density was calculated by the following equation (4).
Relative density (%) = (apparent density of wavelength conversion member / true density of wavelength conversion member) × 100 (4)

  The method for calculating the true density of the wavelength conversion member is a value obtained by multiplying the mass ratio of the alumina particles to the total amount of the YAG-based phosphor and α-alumina particles by the true density of the alumina particles, This is the sum of the mass ratio of the YAG-based phosphor particles to the total amount of the particles and the value obtained by multiplying the true density of the YAG-based phosphor particles. The same numerical values as those used in the method for calculating the true density of the first sintered body were used for the true density of each YAG-based phosphor and the true density of α-alumina particles.

The apparent density of the wavelength conversion member was calculated by the following equation (5).
Apparent density of wavelength conversion member = mass of wavelength conversion member / volume determined by Archimedes method of wavelength conversion member (5)

Measurement of relative light emission intensity The wavelength conversion members of Examples 1 to 19 and Comparative Examples 1 to 4 were cut to a thickness of 300 µm using a wire saw to form samples. Using an LED chip made of a nitride semiconductor having an emission peak wavelength of 455 nm as a light source, the light source irradiates light to a sample of a wavelength conversion member, receives light from the light source, and receives light from the light source. The emission intensity of the emission peak wavelength in the wavelength range of 430 nm to 800 nm obtained from the samples of the wavelength conversion members of Nos. To 4 was measured using a spectrofluorometer (manufactured by Nichia Corporation). Assuming that the emission intensity of the emission peak wavelength in the wavelength range of 430 nm to 800 nm obtained from the sample of the wavelength conversion member of Comparative Example 1 is 100%, the emission peak in the wavelength range of 430 nm to 800 nm obtained from each sample. The emission intensity at the wavelength was expressed as relative emission intensity (%). Table 1 shows the results.

Measurement of Light Conversion Efficiency The wavelength conversion members of Examples 1 to 19 and Comparative Examples 1 to 4 were cut to a thickness of 300 μm using a wire saw to form samples. Using an LED chip made of a nitride semiconductor having an emission peak wavelength of 455 nm as a light source, the light source irradiates light to a sample of the wavelength conversion member, and the sample of the wavelength conversion member in the wavelength range of 430 nm to 480 nm is absorbed. The amount of photons to be emitted and the amount of photons emitted from the sample of the wavelength conversion member in the wavelength range of 490 nm to 800 nm were measured using an integrating sphere under the following measurement conditions. The ratio of the amount of photons emitted from the sample of the wavelength conversion member in the wavelength range of 490 nm to 800 nm to the amount of photons absorbed by the sample of the wavelength conversion member in the wavelength range of 430 nm to 480 nm is expressed as a percentage, and the light conversion efficiency is expressed as a percentage. (%). Table 1 shows the results.
Light conversion efficiency measurement conditions Excitation light source current value: 800 mA
Excitation light source drive method: pulse (period: 5 msec, Duty: 1%)
Detector: Multi-channel spectrometer

SEM photograph Using a scanning electron microscope (SEM), SEM photographs of the cross sections of the wavelength conversion members of Example 1 and Example 11 were obtained. FIG. 3 is an SEM photograph of a cross section of the wavelength conversion member of Example 1. FIG. 4 is an SEM photograph of a cross section of the wavelength conversion member of Example 11.

Appearance photograph An appearance photograph of Example 1 was obtained. FIG. 5 is an external photograph of the wavelength conversion member of Example 1.

  As shown in Table 1, a molded body containing a YAG-based phosphor having a composition represented by the formula (I) and alumina particles having an alumina purity of 99.0% by mass or more was prepared and subjected to primary firing and secondary firing. For the wavelength conversion members of Examples 1 to 19 obtained as described above, a molded body containing a YAG-based phosphor not having the composition represented by the formula (I) and alumina particles was prepared, and primary firing and secondary firing were performed. It had a higher relative luminous intensity than the wavelength conversion members of Comparative Examples 1 to 4 obtained by firing, and had a higher light conversion efficiency than Comparative Example 1.

As shown in Table 1, in the wavelength conversion member of Example 14, the average particle diameter of the YAG-based phosphor was larger than 10 μm, and the content of the YAG-based phosphor in the mixed powder constituting the compact was reduced. When it was increased to 50% by mass, the relative emission intensity was high and the light conversion efficiency was high, but the relative density was 97% or less.

  As shown in Table 1, when the average particle diameter of the YAG-based phosphor is larger than 10 μm, the wavelength conversion members of Examples 16 to 18 reduce the total amount of the YAG-based phosphor and alumina particles to 100% by mass. On the other hand, even when the content of the YAG-based phosphor was reduced to 5% by mass or more and 10% by mass or less, the relative emission intensity was higher by 120% or more than that of the wavelength conversion member of Comparative Example 1 or Comparative Example 2.

  As shown in the SEM photograph of FIG. 3, the wavelength conversion member of Example 1 has YAG-based phosphor particles that are distinguished from the alumina matrix by grain boundaries in the fused alumina 2 that constitutes the matrix of the sintered body. 1 and alumina 2 constituting the matrix and the YAG-based phosphor particles 1 were integrally formed to form a ceramic wavelength conversion member.

As shown in the SEM photograph of FIG. 4, the wavelength conversion member of Example 11 including the YAG-based phosphor particles 1 having a large average particle size of 12 μm was clearly distinguished from the alumina 2 constituting the matrix by the grain boundaries. The system phosphor particles 1 can be confirmed.
Although not shown, the wavelength conversion members of Examples 1 to 19 are used for primary and secondary firing of a mixed powder obtained by mixing previously produced YAG-based phosphor particles and alumina particles to obtain a wavelength conversion member. A wavelength conversion member having high emission intensity and high light conversion efficiency can be obtained without impairing the characteristics of the YAG-based phosphor in the wavelength conversion member.

  As shown in the external appearance photograph of FIG. 5, the wavelength conversion member of Example 1 is bright overall and maintains the original body color of the YAG-based phosphor, and is deteriorated by primary firing and secondary firing by HIP processing. It was confirmed that it did not.

  As shown in Comparative Examples 1 to 4 in Table 1, a molded article containing a YAG-based phosphor not having the composition represented by the formula (I) and alumina particles was obtained by primary firing and secondary firing. The wavelength conversion member according to Example 5 in which the content of the YAG-based phosphor in the mixed powder constituting the molded body was the same as the content of the YAG-based phosphor of 20% by mass even when the content of the YAG-based phosphor was increased to 20% by mass. Also had a low relative emission intensity and a low light conversion efficiency.

  Next, Examples 21 to 29 and 32 and 34 to 36 and Comparative Examples 31 and 33 will be described.

Production Example 1-1 to Production Example 1-3
20 parts by mass of a YAG-based phosphor represented by Y ₃ Al ₅ O ₁₂ : Ce having an average particle diameter of 20 μm (also represented by (Y _0.978 Ce _0.022 ) ₃ Al ₅ O ₁₂ ), and 80 parts by mass of α-alumina particles having a particle size of 0.40 μm (product name: AHP200, manufactured by Nippon Light Metal Co., Ltd.) were weighed and mixed by a dry ball mill. After removing the ball used as the mixing medium from the mixed powder, the mixed powder was filled in a mold, and a cylindrical molded body having a diameter of 20 mm and a thickness of 20 mm was formed at a pressure of 19.6 MPa (200 kgf / cm ² ). Formed. The obtained molded body was placed in a packaging container, vacuum-packaged, and subjected to a CIP treatment at 176 MPa by a cold isostatic pressing device (manufactured by KOBELCO). The obtained molded body is kept at 1700 ° C., 1750 ° C., and 1780 ° C. for 6 hours in a firing furnace (manufactured by ADVANTEC) in an air atmosphere (oxygen concentration: about 20% by volume), and primary fired at each temperature. Was performed to obtain each first sintered body of Production Example 1-1, Production Example 1-2, and Production Example 1-3.

Production Example 2-1 to Production Example 2-3
Production Example 2-1 was performed in the same manner as in Production Examples 1-1 to 1-3 except that α-alumina particles having an average particle diameter of 0.46 μm (product name: AKP-20, manufactured by Sumitomo Chemical Co., Ltd.) were used. Obtained the first sintered bodies of Production Examples 2-3.

Production Example 3-1 to Production Example 3-3
Production Example 3-1 except that α-alumina particles having an average particle size of 1.00 μm (product name: RA-40, manufactured by Iwatani Corporation) were used in the same manner as Production Examples 1-1 to 1-3. Obtained the respective first sintered bodies of Production Example 3-3.

Production Example 4-1 to Production Example 4-3
Except for using α-alumina particles having an average particle size of 1.30 μm (product name: AHP300, manufactured by Nippon Light Metal Co., Ltd.), the same procedure as in Production Examples 1-1 to 1-3 was used to produce from Production Example 4-1. Each first sintered body of Example 4-3 was obtained.

Production Example 5-1 to Production Example 5-3
Except that activated alumina particles (γ-alumina) having an average particle size of 0.51 μm (product name: RG-40, manufactured by Iwatani Sangyo Co., Ltd.) were used, and produced in the same manner as in Production Examples 1-1 to 1-3. Each first sintered body of Example 5-1 to Production Example 5-3 was obtained.
Production Example 6
Production Example 1-1 except that the obtained molded body was primary-baked in a firing furnace (manufactured by ADVANTEC) in an air atmosphere (oxygen concentration: about 20% by volume) at a temperature of 1650 ° C. for 6 hours. In the same manner as in the above, a first sintered body of Production Example 6 was obtained.

Measurement of Relative Density of First Sintered Body The relative density of each first sintered body of Production Example 1-1 to Production Example 5-3 and Production Example 6 was measured. Table 2 shows the results.
The relative density was calculated by the following equation (1).
Relative density (%) = (apparent density of first sintered body ÷ true density of first sintered body) × 100 (1)
The true density of the first sintered body was calculated from the following equation (2). True density of the α-alumina particles used in Examples and Comparative Examples was set to 3.98 g / cm ^3, the true density of the YAG phosphor was calculated as 4.60 g / cm ^3. Table 2 shows the true density of the first sintered body in each production example.
True density of first sintered body = (mass ratio of YAG-based phosphor to total amount of YAG-based phosphor and alumina particles × true density of YAG-based phosphor) + (total amount of YAG-based phosphor and alumina particles) (Mass ratio of alumina particles with respect to the actual density of alumina particles) (2)
The apparent density of the first sintered body was calculated by the following equation (3).
Apparent density of first sintered body = mass of first sintered body / volume of first sintered body determined by Archimedes method (3)

Measurement of Alumina Purity After measuring the mass of the alumina particles, each of the alumina particles was fired at 800 ° C. for 1 hour in an air atmosphere to remove organic components attached to the alumina particles and moisture absorbed by the alumina particles. . The mass of the alumina particles after the calcination was measured, and the mass of the alumina particles after the calcination was divided by the mass of the alumina particles before the calcination, whereby the alumina purity was calculated by the following equation (6). Table 2 shows the alumina purity of each alumina particle.
Alumina purity (% by mass) = (mass of alumina particles after firing / mass of alumina particles before firing) × 100 (6)

  As shown in Table 2, alumina particles having an alumina purity of 99.0% by mass or more and an average particle size of 0.2 μm or more and 1.3 μm or less have a relative density of 95% or more together with the YAG-based phosphor particles. A first sintered body having a high density can be formed. When the average particle size of the alumina particles is 0.2 μm or more and 1.0 μm or less, if the primary firing temperature is in the range of 1700 ° C. or more and 1750 ° C. or less, the relative density has a higher density of 95.9% or more. A first sintered body can be formed. When alumina particles having an alumina purity of less than 99.0% by mass were used, the relative density of the first sintered body was reduced to less than 95% as shown in Production Examples 5-1 to 5-3.

  Next, Examples 21 to 29, 32, 34 to 36, and 37 of the wavelength conversion member manufactured using the first sintered body obtained in Production Example 1-1 were not subjected to HIP processing and annealing. Comparative Example 31 and Comparative Example 33 using glass particles instead of alumina particles will be described.

Example 21
The first sintered body obtained in Production Example 1-1 was placed under a nitrogen gas atmosphere (nitrogen: 99% by volume or more) using a HIP apparatus (manufactured by KOBELCO) and a nitrogen gas as a pressure medium. Then, HIP treatment was performed at 1700 ° C. and 198 MPa for 2 hours to obtain a second sintered body. The obtained second sintered body was annealed at 1500 ° C. for 5 hours in an air atmosphere (oxygen: about 20% by volume) using an air firing furnace (manufactured by Marusho Denki Co., Ltd.) to obtain a wavelength conversion member. Obtained.

Example 22
A wavelength conversion member was obtained in the same manner as in Example 21 except that annealing was performed at 1600 ° C.

Example 23
A wavelength conversion member was obtained in the same manner as in Example 21 except that annealing was performed at 1700 ° C.

Example 24
A wavelength conversion member was obtained in the same manner as in Example 21, except that the HIP treatment was performed at 1740 ° C and the annealing was performed at 1600 ° C.

Example 25
A wavelength conversion member was obtained in the same manner as in Example 21, except that the HIP treatment was performed at 1750 ° C and the annealing was performed at 1600 ° C.

Example 26
A wavelength conversion member was obtained in the same manner as in Example 21, except that the HIP treatment was performed at 1760 ° C and the annealing was performed at 1600 ° C.

Example 27
A wavelength conversion member was obtained in the same manner as in Example 21, except that the HIP treatment was performed at 1770 ° C and the annealing was performed at 1600 ° C.

Example 28
A wavelength conversion member was obtained in the same manner as in Example 21, except that the HIP treatment was performed at 1780 ° C and the annealing was performed at 1600 ° C.

Example 29
A wavelength conversion member was obtained in the same manner as in Example 31, except that the HIP treatment was performed at 1790 ° C and the annealing was performed at 1600 ° C.

Comparative Example 31
The first sintered body obtained in Production Example 1-1 was used as a wavelength conversion member of Comparative Example 31 without performing HIP processing and annealing.

Example 32
The first sintered body obtained in Production Example 1-1 was placed in a nitrogen gas atmosphere (nitrogen: 99% by volume or more) using a HIP apparatus (product name: manufactured by KOBELCO) and using nitrogen gas as a pressure medium. Originally, HIP treatment was performed at 1700 ° C. and 198 MPa for 2 hours to obtain a second sintered body. The second sintered body was used as the wavelength conversion member of Example 32 without performing annealing.

Comparative Example 33
11 parts by mass of a YAG-based phosphor represented by Y ₃ Al ₅ O ₁₂ : Ce having an average particle size of 20 μm and 89 parts by mass of borosilicate glass powder (manufactured by Matsunami Glass Industry Co., Ltd.) were weighed and mixed by a dry ball mill. . After removing the ball used as the mixing medium from the mixed powder, the mixed powder was filled in a mold, and a cylindrical molded body having a diameter of 20 mm and a thickness of 20 mm was formed at a pressure of 19.6 MPa (200 kgf / cm ² ). Formed. The obtained molded body was placed in a packaging container, vacuum-packaged, and subjected to a CIP treatment at 176 MPa by a cold isostatic pressing device (manufactured by KOBELCO). The obtained molded body is kept in a firing furnace (manufactured by ADVANTEC) in an air atmosphere (oxygen concentration: about 20% by volume) at a temperature of 800 ° C. for 6 hours to perform primary firing to obtain a sintered body. However, it could not be taken out by melting in the firing furnace.

Example 34
A wavelength conversion member was obtained in the same manner as in Example 21, except that annealing was performed at 1400 ° C. for 5 hours in a reducing atmosphere having an oxygen concentration of less than 1% by volume.

Example 35
A wavelength conversion member was obtained in the same manner as in Example 34 except that annealing was performed at 1500 ° C.

Example 36
A wavelength conversion member was obtained in the same manner as in Example 34 except that annealing was performed at 1600 ° C.

Example 37
The first sintered body obtained in Production Example 6 was subjected to a nitrogen gas atmosphere (nitrogen: 99% by volume or more) using a HIP device (product name: manufactured by KOBELCO) and using nitrogen gas as a pressure medium. Then, HIP processing was performed at 1650 ° C. and 198 MPa for 2 hours to obtain a second sintered body. The second sintered body was used as the wavelength conversion member of Example 37 without performing annealing.
The relative densities, relative emission intensities, and light conversion efficiencies of the wavelength conversion members of Examples 21 to 29, 32, 34 to 36, and 37 and Comparative Example 31 were the same as those of Examples 1 to 19 and Comparative Examples 1 to 4. The measurement was performed using the same method as the measurement.
The method for calculating the true density of the wavelength conversion member is a value obtained by multiplying the mass ratio of the alumina particles to the total amount of the YAG-based phosphor and α-alumina particles by the true density of the alumina particles, This is the sum of the mass ratio of the YAG-based phosphor particles to the total amount of the particles and the value obtained by multiplying the true density of the YAG-based phosphor particles. true density of the α-alumina particles and 3.98 g / cm ^3, the true density of the YAG phosphor was calculated as 4.60 g / cm ^3.
The relative emission intensity is defined as a wavelength of 430 nm or more and 800 nm or less obtained from each sample, with 100% as the emission intensity of the emission peak wavelength in the wavelength range of 430 nm or more and 800 nm or less obtained from the sample of the wavelength conversion member of Comparative Example 31. The emission intensity of the emission peak wavelength in the range was expressed as relative emission intensity (%). Table 3 shows the results.

SEM photograph Using a scanning electron microscope (SEM), SEM photographs of the cross sections of the wavelength conversion members of Example 21 and Comparative Example 31 were obtained. FIG. 6 is an SEM photograph of a cross section of the wavelength conversion member of Example 21. FIG. 7 is an SEM photograph of a cross section of the wavelength conversion member of Comparative Example 31.

Photographs of external appearance Photographs of Comparative Example 31, Example 32, Example 21, and Example 34 were obtained. FIG. 8 is an external photograph of the wavelength conversion member of Comparative Example 31. FIG. 9 is an external photograph of the wavelength conversion member of Example 32. FIG. 10 is an external photograph of the wavelength conversion member of Example 21. FIG. 11 is an external photograph of the wavelength conversion member of Example 34.

  As shown in Table 3, the wavelength conversion members of Examples 21 to 29, 32, 34 to 36, and 37 had higher relative densities and higher relative emission intensities and light conversion efficiencies than the wavelength conversion members of Comparative Example 31. Was. In particular, the wavelength conversion members of Examples 32 and 37 in which the primary firing temperature is 1600 ° C. or more and 1780 ° C. or less and the secondary firing temperature is 1600 ° C. or more and 1780 ° C. Efficiency increased. The wavelength conversion members of Examples 21 to 28 and 34 to 36 in which the temperature of the secondary firing is 1700 ° C. or more and 1780 ° C. or less and the temperature of the annealing is 1400 ° C. or more and 1700 ° C. Conversion efficiency increased.

  On the other hand, the wavelength conversion members of Comparative Example 31 in which the secondary firing and annealing were not performed had lower relative densities and lower light conversion efficiencies than the wavelength conversion members of Examples 21 to 29, 32, 34 to 36, and 37. It was low.

  The wavelength conversion member of Example 32 was not subjected to annealing after the secondary firing by the HIP process, and the secondary firing by the HIP process caused the entire surface of the wavelength conversion member to have a dark blackish color on the entire surface. However, the relative light emission locality and light conversion efficiency were higher than those of the wavelength conversion member of Comparative Example 31.

  In Comparative Example 33, the glass was melted by the secondary firing to change its shape, and the sintered body could not be taken out of the container, and the characteristics of the sintered body could not be obtained. Also, when the HIP treatment was performed at 1800 ° C., the sintered body was melted and could not be taken out of the container.

  After the secondary baking by the HIP treatment, the wavelength conversion members of Examples 34 to 36 were further annealed in a reducing atmosphere, and the appearance of the wavelength conversion member was such that the entire surface was dark and blackish in color. However, relative emission intensity and light conversion efficiency were higher than those of the wavelength conversion member of Comparative Example 31. It is presumed that the reason why the appearance of the wavelength conversion members of Examples 34 to 36 is dark and darkish is that the change in the oxygen composition ratio of the YAG-based phosphor due to the HIP treatment was not restored even after annealing.

  As shown in the SEM photograph of FIG. 6, the wavelength conversion member of Example 21 is obtained by first firing the molded body and then secondary firing by the HIP process. Therefore, the matrix of the YAG-based phosphor particles 1 and the sintered body is obtained. It was confirmed that the voids 3 between the alumina 2 and the alumina 2 included in the sintered body were reduced, and the minute voids 3 formed in the alumina 2 included in the matrix of the sintered body were also reduced.

  As shown in FIG. 6, in the wavelength conversion member of Example 21, in the secondary firing step, in the alumina 2 in which alumina particles were melted to form a matrix, a YAG-based material was distinguished from the alumina matrix by a grain boundary. The phosphor particles 1 were present, and the alumina 2 and the YAG-based phosphor particles 1 constituting the matrix were integrated to form a ceramic wavelength conversion member. The YAG-based phosphor particles in the wavelength conversion member are not mixed with the raw material of the YAG-based phosphor particles and the alumina particles in the compact preparation step before the primary firing to form the YAG-based phosphor particles. And the alumina particles are mixed to form a molded body. Therefore, in the cross-sectional photograph of the wavelength conversion member, the YAG-based phosphor particles 1 Could be distinguished. As shown in FIG. 6, the YAG-based phosphor particles 1 in the wavelength conversion member are scattered in the alumina 2 constituting the matrix while maintaining the shape of each of the YAG-based phosphor particles. Was confirmed.

  On the other hand, as shown in the SEM photograph of FIG. 7, the wavelength conversion member of Comparative Example 31 was not subjected to the secondary firing by the HIP process after the primary firing of the molded body, so that the YAG-based phosphor particles 1 A relatively large void 3 is formed between the sintered body and the alumina 2 forming the matrix, and a minute void 3 is also formed in the alumina 2 forming the sintered body matrix. That was confirmed.

  As shown in FIG. 8, the wavelength conversion member of Comparative Example 31 is obtained by subjecting a molded body to primary firing, and the first sintered body after primary firing is bright overall, and is the original YAG-based phosphor. The body color was maintained, and it was confirmed that the YAG-based phosphor particles contained in the first sintered body were not altered by the primary firing.

  As shown in FIG. 9, the wavelength conversion member of Example 32 is a second sintered body obtained by secondary firing the first sintered body by the HIP processing, and the surface of the second sintered body is The YAG-based phosphor particles contained in the second sintered body were sometimes changed in quality due to the secondary firing by the HIP treatment.

  As shown in FIG. 10, the wavelength conversion member of Example 21 can be returned to the original body color of the YAG-based phosphor by performing annealing under an oxygen-containing atmosphere after secondary firing by HIP processing. As a result, the wavelength conversion member had a bright color as a whole.

  As shown in FIG. 11, the wavelength conversion member of Example 34 was subjected to annealing under a reducing atmosphere after the secondary baking by the HIP treatment, and thus remained entirely dark and blackish in color.

  In Example 32 described above, as shown in Table 3, the relative emission intensity and light conversion efficiency were high as a whole of the wavelength conversion member, but as shown in FIG. May be present. A wavelength conversion member having such a portion is not preferable because a dark-colored portion absorbs light. As in Example 32, when the YAG-based phosphor contained in the second sintered body is deteriorated by the secondary firing due to the HIP treatment and a part of the second sintered body becomes blackish, By annealing the two sintered bodies in an oxygen-containing atmosphere, the original body color of the YAG-based phosphor can be restored as shown in Example 21 of FIG.

  The wavelength conversion member manufactured by the manufacturing method of the present disclosure has high emission intensity, high light conversion efficiency, and can be used as a material for a wavelength conversion member that converts the wavelength of light emitted from an LED or LD, or a solid scintillator.

  1 ... YAG phosphor particles, 2 ... Alumina constituting matrix of sintered body, 3 ... Void.

Claims (17)

Preparing a compact including an yttrium aluminum garnet-based phosphor having a composition represented by the following formula (I) and alumina particles having an alumina purity of 99.0% by mass or more;
Primary firing the molded body in the range of 1200 ° C. or more and 1800 ° C. or less to obtain a first sintered body;
A method for producing a wavelength conversion member, comprising: secondary firing the first sintered body by hot isostatic pressing (HIP) to obtain a second sintered body.
_{(Y 1-a-b Gd} a Ce b) 3 Al 5 O 12 (I)
(In the formula (I), a and b are numbers satisfying 0 <a ≦ 0.3 and 0.0001 ≦ b ≦ 0.022.)   The method for producing a wavelength conversion member according to claim 1, wherein in the formula (I), a and b are numbers satisfying 0.05 ≦ a ≦ 0.25 and 0.0002 ≦ b ≦ 0.012.   The method for manufacturing a wavelength conversion member according to claim 1, further comprising annealing the second sintered body under an oxygen-containing atmosphere.   The method for producing a wavelength conversion member according to claim 1, wherein the primary firing is performed in an oxygen-containing atmosphere.   5. The method for producing a wavelength conversion member according to claim 1, wherein a temperature of the primary firing is in a range of 1600 ° C. to 1780 ° C. 5.   The method for producing a wavelength conversion member according to any one of claims 1 to 5, wherein the secondary firing is performed in an inert gas atmosphere.   The method for producing a wavelength conversion member according to any one of claims 1 to 6, wherein a temperature of the secondary firing is in a range of 1500 ° C or more and less than 1800 ° C.   The method for producing a wavelength conversion member according to claim 1, wherein a temperature of the secondary firing is in a range of 1600 ° C. or more and 1780 ° C. or less. Wherein the second sintered body comprises that anneals under oxygen-containing atmosphere, the temperature of the annealing is in the range of 1200 ° C. or higher 1700 ° C. or less, according to any one of claims 1 8 A method for manufacturing a wavelength conversion member. The average particle size of the yttrium-aluminum-garnet phosphor is 40μm or less in the range of 1 [mu] m, the method for manufacturing a wavelength conversion member according to any one of claims 1 to 9. The average particle size of the yttrium-aluminum-garnet phosphor is 15μm or less in the range of 2 [mu] m, the method for manufacturing a wavelength conversion member according to any one of claims 1 to 10.   The method for producing a wavelength conversion member according to claim 1, wherein the average particle diameter of the alumina particles is in a range of 0.2 μm to 1.0 μm. With respect to the total amount of the yttrium aluminum garnet-based phosphor and the alumina particles, the yttrium aluminum garnet-based phosphor is 3% by mass or more and 50% by mass or less, and the alumina particles are 50% by mass or more and 97% by mass or less. mixed and, to prepare the green body, the method for manufacturing a wavelength conversion member according to any one of the 請 Motomeko 1 to 12. The total amount of the yttrium aluminum garnet phosphor and the alumina particles, and the yttrium-aluminum-garnet phosphor than 15 wt% to 50 wt%, and the alumina particles 50 mass% or more and 85 mass% or less The method for producing a wavelength conversion member according to any one of claims 1 to 13, wherein the mixture is mixed to prepare the molded body . Based on the total amount of the yttrium aluminum garnet-based phosphor and the alumina particles, the yttrium aluminum garnet-based phosphor is 25% by mass or more and 50% by mass or less, and the alumina particles are 50% by mass or more and 75 % by mass or less . The method for producing a wavelength conversion member according to any one of claims 1 to 14, wherein the mixture is mixed to prepare the molded body .   The method according to any one of claims 1 to 15, wherein the relative density of the first sintered body is 95% or more. The method for manufacturing a wavelength conversion member according to any one of claims 1 to 16, wherein the relative density of the wavelength conversion member is 97% or more.

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