JP2020193142A - Method of producing sintered wavelength conversion body - Google Patents

Abstract

To provide a method for producing a sintered wavelength conversion body that emits light when irradiated with excitation light.SOLUTION: A method for producing a sintered wavelength conversion body, comprising: preparing a molded body from a mixture containing α-SiAlON phosphor and aluminum oxide particles having a Ga content of 15 mass ppm or less; and subjecting the molded body to a primary sintering at a temperature within the range of 1,370 to 1,600°C to obtain a first sintered body.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a wavelength conversion sintered body.

A light emitting device using a light emitting diode (Light Emitting Diode, hereinafter also referred to as "LED") or a laser diode (Laser Diode, hereinafter also referred to as "LD") is composed of a light emitting element which is a light source and a light emitting element. It is provided with a diode conversion member that absorbs a part of the light emitted from the light and converts it into a different diode. Such light emitting devices are used in a wide range of fields such as light emitting devices for automobiles and indoor lighting, backlight light sources for liquid crystal display devices, illuminations, and light source devices for projectors.

As the phosphor used in such a light emitting device, for example, a rare earth aluminate phosphor and a phosphor such as an α-sialon phosphor contained in the wavelength conversion member disclosed in Patent Document 1 are known. Further, as a wavelength conversion member containing a phosphor, for example, Patent Document 2 also discloses a wavelength conversion member made of a sintered body obtained by mixing glass and a phosphor and melting and solidifying the glass.

International Publication No. 2015/133612 Japanese Unexamined Patent Publication No. 2014-234487

However, the wavelength conversion member disclosed in Patent Documents 1 and 2 may have insufficient heat dissipation from the phosphor when the light emitting device is configured. Further, in the wavelength conversion member disclosed in Patent Document 2, the glass component may act on the composition of the phosphor during the formation of the sintered body, which may adversely affect the light emission of the phosphor. Due to these circumstances, there is a concern that the emission intensity of the wavelength conversion member may decrease.
Therefore, an object of the present invention is to provide a method for producing a wavelength-converted sintered body in which a desired emission intensity can be obtained.

One aspect of the present invention is to prepare a molded product of a mixture containing an α-sialon phosphor and aluminum oxide particles and having a Ga content of 15 mass ppm or less, and to prepare the molded product at 1370 ° C. or higher. This is a method for producing a wavelength conversion sintered body, which comprises first firing at a temperature in the range of 1600 ° C. or lower to obtain a first sintered body.

According to the present invention, it is possible to provide a method for producing a wavelength conversion sintered body capable of obtaining a desired emission intensity.

FIG. 1 is a flowchart showing a method for manufacturing a wavelength conversion sintered body. FIG. 2 is a flowchart showing a method for manufacturing a wavelength conversion sintered body. FIG. 3 is an external photograph of the wavelength conversion sintered body according to Example 7. FIG. 4 is an external photograph of the wavelength conversion sintered body according to Comparative Example 1. FIG. 5 is an external photograph of the wavelength conversion sintered body according to Comparative Example 2.

Hereinafter, an embodiment of a method for producing a wavelength conversion sintered body according to the present invention will be described. However, the embodiments shown below are examples for embodying the technical idea of the present invention, and the present invention is not limited to the following method for producing a wavelength conversion sintered body. The relationship between the color name and the chromaticity coordinate, the relationship between the wavelength range of light and the color name of monochromatic light, and the like are in accordance with JIS Z8110.

Method for producing wavelength-converted sintered body The method for producing a wavelength-converted sintered body includes α-sialone phosphor and aluminum oxide particles, and may contain rare earth aluminate if necessary. This includes preparing a molded product of a mixture having an amount of 15 mass ppm or less, and primary firing the molded product at a temperature in the range of 1370 ° C. or higher and 1600 ° C. or lower to obtain a first sintered body. .. The wavelength conversion sintered body composed of the first sintered body contains at least an α-sialon phosphor and aluminum oxide, but in addition to these, a rare earth aluminate phosphor may be further contained. Since the wavelength conversion sintered body made of the first sintered body contains aluminum oxide, which is a material having a relatively high thermal conductivity, heat dissipation can be improved as compared with those containing, for example, a glass component.

A mixture containing an α-sialon phosphor and aluminum oxide particles and optionally containing a rare earth aluminate phosphor is formed, and the molded body is sintered to obtain a sintered body. At this time, if gallium oxide (Ga ₂ O ₃ ) is contained in a very small amount in the mixture, gallium oxide inhibits the sintering of aluminum oxide particles, and voids are formed in the sintered body. The relative density of the sintered body may be low. In a sintered body having a low relative density, the excitation light is scattered in the voids in the sintered body, or the excitation light incidented by the voids escapes from the sintered body, and the efficiency of wavelength conversion by the phosphor is reduced. However, the emission intensity may decrease. In addition, when gallium oxide is contained in the mixture, Ga in the oxide reacts with the α-sialon phosphor, the body color of the α-sialon phosphor becomes dull, and the light emitted from the wavelength conversion sintered body becomes dull. The chromaticity may change. It is not clear why the sintering of aluminum oxide particles is inhibited and the body color of the α-sialon phosphor changes when gallium oxide is contained in the mixture. For example, gallium oxide has a relatively low melting point of 1700 ° C to 1900 ° C. When gallium oxide is contained in the mixture, it is presumed that gallium oxide, which has a relatively low melting point, inhibits the sintering of aluminum oxide particles and facilitates the reaction between Ga in the oxide and the α-sialon phosphor. .. When the temperature at which the molded product is first fired is 1370 ° C. or higher, gallium oxide having a low melting point is released before reacting with the aluminum oxide particles even if the mixture contains a small amount of gallium oxide. Evaporate. Therefore, the inhibition of sintering of aluminum oxide particles by gallium oxide is suppressed, and the reaction between Ga in gallium oxide and the α-sialon phosphor tends to be suppressed easily. When the temperature at which the molded product is first fired is, for example, less than 1370 ° C., even if a small amount of gallium oxide is contained in the mixture, gallium oxide does not evaporate and inhibits sintering of aluminum oxide particles. Due to the presence of many voids in the obtained first sintered body, light scattering tends to be too large in the sintered body, and the emission intensity tends to decrease. In the present specification, the case where a small amount of gallium oxide is contained means that the content of Ga in the mixture (hereinafter, also referred to as “Ga amount”) is 15 mass ppm or less. The amount of Ga in the mixture containing the α-sialon phosphor and the aluminum oxide particles and, if necessary, the rare earth aluminate phosphor is more preferably 12 mass ppm or less, still more preferably 10 mass ppm or less. It may be 0.01 mass ppm or more, or 0.1 mass ppm or more.

When the content of Ga contained in the mixture constituting the molded product is 15 mass ppm or less and the temperature of the primary firing is 1370 ° C. or higher, the sintering inhibition of the aluminum oxide particles in the primary firing is less likely to occur. As a result, the first sintered body can form a wavelength-converted sintered body in which the relative density is increased and the light from the excitation light can be wavelength-converted to a desired chromaticity. Ga contained in the mixture is subjected to elemental analysis of the elements contained in the mixture using, for example, an inductively coupled plasma atomic emission spectroscopic (ICP-AES), and the results of the elemental analysis obtained are obtained. The Ga content can be measured. Alternatively, the amount of Ga contained in the α-sialon phosphor, aluminum oxide particles, or rare earth aluminate phosphor as a raw material is measured by ICP-AES, and the amount of Ga contained in each raw material and the mixture of each raw material are used. It is also possible to calculate the amount of Ga contained in the mixture from the blending ratio of.

The first sintered body contains an α-sialon phosphor and aluminum oxide particles, and may contain a rare earth aluminate phosphor if necessary, and has a Ga content of 15 mass ppm or less. It is obtained by primary firing the molded product of the mixture. Therefore, the α-sialone phosphor maintains the crystal structure of the α-sialon phosphor without partially decomposing the crystal structure. In addition, the α-sialon phosphor reacts with Ga contained in gallium oxide to be hardened together with aluminum oxide particles and a rare earth aluminate phosphor without dull body color, and has a desired emission peak wavelength by excitation light. A wavelength-converted sintered body that emits light can be obtained.

When an oxynitride phosphor such as an α-sialone phosphor is fired together with aluminum oxide particles, nitrogen contained in the composition of the oxynitride phosphor and oxygen in the oxide easily react with each other. Therefore, it was speculated that the crystal structure of the α-sialon phosphor would change, and a sintered body containing the phosphor that emits light to a practical extent could not be obtained. However, aluminum oxide is relatively less susceptible to changes in composition due to heat, aluminum oxide is less likely to be decomposed to generate oxygen, and the α-sialon phosphor is less likely to be adversely affected. Therefore, even if a sintered body is formed using aluminum oxide particles, it is unlikely to adversely affect the light emission of the α-sialon phosphor. Furthermore, since the Ga content in the mixture is 15 mass ppm or less, the sintering of aluminum oxide particles is not hindered, the excitation light is wavelength-converted to a desired chromaticity, and a wavelength-converted sintered body having high emission intensity is obtained. Obtainable.

Aluminum contained in aluminum oxide is the same Group 13 element as gallium, and a small amount of gallium may be contained in aluminum oxide as, for example, an oxide or a composite oxide. Further, the rare earth aluminate phosphor may contain Ga depending on its composition and production method. Even when aluminum oxide is contained in the mixture constituting the molded product and, if necessary, a rare earth aluminate phosphor is contained, if the Ga content in the mixture is 15% by mass or less, α-sialon. It is possible to obtain a first sintered body containing an α-sialon phosphor, aluminum oxide particles and a rare earth aluminate phosphor without dull body color of the phosphor and without inhibiting the sintering of aluminum oxide. it can.

α-Sialon Fluorescent Form The α-sialon fluorescent substance preferably has a composition represented by the following formula (I).
M _k Si _{12- (m + n)} Al _{m + n On} N _16-n : Eu (I)
(In formula (I), M is at least one element selected from the group consisting of Li, Mg, Ca, Sr, Y and lanthanoid elements (excluding La and Ce), and k, m, n is a number that satisfies 0 <k ≦ 2.0, 2.0 ≦ m ≦ 6.0, and 0 ≦ n ≦ 1.0.)
The α-sialone phosphor may have a composition represented by the following formula (II).
_{Ca v (Si, Al) 12} (O, N) 16: Eu (II)
(In formula (II), v is a number that satisfies 0 <v≤2.)
In the present specification, in the formula expressing the composition of the phosphor, the element before the colon (:) represents the element constituting the parent crystal and its molar ratio, and after the colon (:), the activating element is represented. In addition, the plurality of elements separated by commas (,) mean that at least one element among these plurality of elements is contained in the composition. The plurality of elements described separated by commas (,) in the composition formula include at least one element selected from the plurality of elements separated by commas in the composition, and two kinds from the plurality of elements. The above may be included in combination.

The α-sialon phosphor used as a raw material for the first sintered body is preferably a powder. The α-sialone phosphor contains aluminum (Al), which is a Group 13 element of the same family as Ga, in its composition, but the α-sialon phosphor reacts with Ga in a trace amount of gallium oxide as described above. Since the body color tends to be dull, Ga is rarely contained in the α-sialon phosphor. For example, even when Ga is contained as an oxide, the amount of Ga is, for example, the amount of Ga measured by ICP-AES. However, it is less than the detection limit and less than 20 mass ppm. The volume median diameter measured by the laser diffraction particle size distribution measurement method of the α-sialon phosphor is preferably in the range of 2 μm or more and 30 μm or less, more preferably in the range of 3 μm or more and 25 μm or less, and further preferably 4 μm or more. It is in the range of 20 μm or less, and more preferably in the range of 5 μm or more and 15 μm or less. When the volume median diameter of the α-sialon phosphor is 2 μm or more, the α-sialon phosphor can be dispersed substantially uniformly in the mixture, and the α-sialon phosphor can be dispersed substantially uniformly even in the molded product. it can. When the volume median diameter of the α-sialon phosphor is 30 μm or less, the voids in the wavelength conversion sintered body are reduced, so that the emission intensity can be increased. In the present specification, the volume median diameter of the α-sialon phosphor is the particle size (volume median diameter) at which the cumulative volume frequency from the small diameter side in the volume-based particle size distribution measured by the laser diffraction / scattering particle size distribution measurement method reaches 50%. ). The laser diffraction particle size distribution measuring method can be measured using, for example, a laser diffraction particle size distribution measuring device (product name: MASTER SIZER3000, manufactured by MALVERN).

The content of the α-sialon phosphor is preferably in the range of 0.1% by mass or more and 40% by mass or less in terms of the mass ratio of the charged material with respect to 100% by mass of the mixture constituting the molded product, and more preferably. It is in the range of 0.5% by mass or more and 38% by mass or less, more preferably in the range of 0.8% by mass or more and 35% by mass or less, and even more preferably in the range of 1% by mass or more and 30% by mass or less. Is. When the content of the α-sialon phosphor is in the range of 0.1% by mass or more and 40% by mass or less with respect to 100% by mass of the mixture constituting the molded body, a wavelength conversion sintered body having high emission intensity is obtained. be able to. If the content of the α-sialon phosphor in the mixture constituting the molded product is less than 0.1% by mass, a wavelength-converted sintered body having a desired emission intensity cannot be obtained. Further, when the content of the α-sialon phosphor in the mixture constituting the molded product exceeds 40% by mass, the content of alumina particles becomes relatively small, and the density of the obtained wavelength conversion sintered body becomes low. , Mechanical strength may decrease. Further, when the content of the α-sialon phosphor exceeds 40% by mass, the thickness of the wavelength conversion sintered body must be reduced in order to obtain a desired color tone and emission intensity, for example, and the wavelength conversion sintered body must be thinned. It may be difficult to handle because the desired strength of the body cannot be obtained.

Aluminum Oxide Particles The aluminum oxide particles used as the raw material of the first sintered body have an aluminum oxide purity of preferably 99.0% by mass or more, more preferably 99.5% by mass or more. The first sintered body obtained by firing a molded body composed of a mixture containing aluminum oxide particles having a purity of aluminum oxide of 99.0% by mass or more or the second sintered body described later has translucency. A wavelength-converted sintered body having high emission intensity can be obtained by increasing the height. The higher the purity of the aluminum oxide particles, the smaller the amount of Ga such as gallium oxide contained, the α-sialon phosphor and the aluminum oxide particles, and if necessary, the rare earth aluminate phosphor. The amount of Ga contained in the good mixture can be reduced. When commercially available aluminum oxide particles are used, the purity of aluminum oxide can be referred to the value of the purity of aluminum oxide described in the catalog. When the purity of aluminum oxide is unknown, the mass of the aluminum oxide particles is measured, and then the aluminum oxide particles are fired at 800 ° C. for 1 hour in an air atmosphere to produce organic components adhering to or adsorbed on the aluminum oxide particles. The purity of aluminum oxide particles is measured by removing water and water, measuring the mass of aluminum oxide particles after firing, and dividing the mass of aluminum oxide particles after firing by the mass of aluminum oxide particles before firing. Can be done. The purity of the aluminum oxide particles can be calculated by, for example, the following formula (1).

The average particle size of the aluminum oxide particles is preferably in the range of 0.1 μm or more and 1.3 μm or less, more preferably in the range of 0.2 μm or more and 1.0 μm or less, and further preferably in the range of 0.3 μm or more and 0. It is in the range of 8.8 μm or less, and more preferably in the range of 0.3 μm or more and 0.6 μm or less. When the average particle size of the aluminum oxide particles is in the range of 0.1 μm or more and 1.3 μm or less, the powder of the α-sialon phosphor, the aluminum oxide particles, and if necessary, the rare earth aluminate phosphor. Can be uniformly mixed, and a wavelength conversion sintered body made of a sintered body having a small number of voids and a high density can be produced. In the present specification, the average particle size of aluminum oxide particles is defined as the average particle size (Fisher Sub-Sieve Sizar's) measured by the Fisher Sub-Sieve Sizar method (hereinafter, also referred to as “FSSS method”). Number). The FSSS method is a kind of air permeation method, and is a method of measuring the specific surface area by utilizing the flow resistance of air to determine the particle size.

With respect to 100% by mass of the mixture constituting the molded product, the content of the aluminum oxide particles is α in the mixture in the mass ratio of the charge, except for the substances contained in the range of 100% by mass (0.01% by mass) or less. -The balance excluding the sialon phosphor, preferably in the range of 60% by mass or more and 99.9% by mass or less, more preferably in the range of 62% by mass or more and 99.5% by mass or less, and further preferably in the range of 62% by mass or more and 99.5% by mass or less. It is in the range of 65% by mass or more and 99.2% by mass or less, and more preferably 70% by mass or more and 99.0% by mass or less. With respect to 100% by mass of the mixture constituting the molded product, the content of the aluminum oxide particles is α in the mixture in the mass ratio of the charge, except for the substances contained in the range of 100% by mass (0.01% by mass) or less. -The balance excluding the sialon phosphor and the rare earth aluminate phosphor, preferably in the range of 30% by mass or more and 99.9% by mass or less, and more preferably in the range of 35% by mass or more and 99.5% by mass or less. It is in the range of 40% by mass or more and 99.2% by mass or less, and particularly preferably in the range of 50% by mass or more and 98% by mass or less.

The type of aluminum oxide constituting the aluminum oxide particles is not particularly limited, and examples of the crystal form of aluminum oxide include α, γ, δ, and θ, and any crystal form of aluminum oxide can be used. It is preferable to use α-alumina because aluminum oxide is easily available, the α-sialon phosphor and aluminum oxide particles are easily mixed, and a molded product is easily formed.

Rare earth aluminate phosphor The mixture constituting the molded product may contain a rare earth aluminate phosphor. The rare earth aluminate phosphor is a fluorescent substance having an yttrium aluminum garnet-based crystal structure (hereinafter, also referred to as “YAG-based phosphor”) or a fluorescent substance having a yttrium aluminum garnet-based crystal structure in which yttrium is replaced with lutetium. (Hereinafter, also referred to as "LAG-based phosphor") can be used. As the YAG-based phosphor, for example, a phosphor having a composition represented by (Y, Gd, Tb, Lu) ₃ Al ₅ O ₁₂ : Ce can be used.

The YAG-based phosphor preferably has a composition represented by the following formula (III).
(Y _1-ab Gd _a Ce _b ) ₃ Al ₅ O ₁₂ (III)
(In formula (III), a and b are numbers satisfying 0 ≦ a ≦ 0.500 and 0 <b ≦ 0.030.)

The LAG-based phosphor preferably has a composition represented by the following formula (IV).
(Lu _1-c Ce _c ) ₃ Al ₅ O ₁₂ (IV)
(In formula (IV), c is a number satisfying 0 <c ≦ 0.100.)

The rare earth aluminate phosphor used as a raw material for the first sintered body is preferably a powder. The rare earth aluminate phosphor preferably does not contain Ga. Even when the rare earth aluminate phosphor contains Ga, the amount of Ga in the mixture containing the rare earth aluminate phosphor measured by, for example, ICP-AES is less than 20 mass ppm below the detection limit. The amount is preferable. In order to reduce the amount of Ga contained in the rare earth aluminate phosphor, it is preferable to produce a rare earth aluminate phosphor having a Ga amount of less than 20 mass ppm by using a raw material having a small amount of Ga. When a commercially available rare earth aluminate phosphor is used, for example, it is preferable to use a rare earth aluminate phosphor having a Ga amount measured by ICP-AES or a Ga amount in the catalog value of less than 20 mass ppm. The average particle size of the rare earth aluminate phosphor is preferably in the range of 1 μm or more and 50 μm or less, more preferably in the range of 1 μm or more and 40 μm or less, and further preferably in the range of 2 μm or more and 30 μm or less. It is even more preferably in the range of 2 μm or more and 20 μm or less, and particularly preferably in the range of 2 μm or more and 15 μm or less. When the average particle size of the rare earth aluminate phosphor is 1 μm or more, the rare earth aluminate phosphor is dispersed substantially uniformly in the mixture, and the rare earth aluminate phosphor is dispersed substantially uniformly in the molded product. be able to. When the average particle size of the rare earth aluminate phosphor is 50 μm or less, the voids in the wavelength conversion sintered body are reduced, so that the emission intensity can be increased. In the present specification, the average particle size of the rare earth aluminate phosphor means the average particle size measured by the FSSS method.

The content of the α-sialon phosphor or the total content of the α-sialon phosphor and the rare earth aluminate phosphor is the mass ratio of the charge to 100% by mass of the mixture constituting the molded product. It is preferably in the range of 0.1% by mass or more and 70% by mass or less, more preferably in the range of 0.5% by mass or more and 65% by mass or less, and further preferably 0.8% by mass or more and 60% by mass or less. It is in the range of 1% by mass or more and 55% by mass or less, and particularly preferably 2% by mass or more and 50% by mass or less. The content of the α-sialon phosphor or the total content of the α-sialon phosphor and the rare earth aluminate phosphor is 0.1% by mass or more and 70% by mass with respect to 100% by mass of the mixture constituting the molded product. If it is within the range of mass% or less, a wavelength conversion sintered body having high emission intensity can be obtained. The content of the α-sialon phosphor or the total content of the α-sialon phosphor and the rare earth aluminate phosphor is less than 0.1% by mass with respect to 100% by mass of the mixture constituting the molded product. Therefore, it is not possible to obtain a wavelength-converted sintered body having a desired emission intensity. Further, when the content of the α-sialon phosphor with respect to 100% by mass of the mixture constituting the molded product or the total content of the α-sialon phosphor and the rare earth aluminate phosphor exceeds 70% by mass, it is relative. Since the content of the fluorescent substance contained in the first sintered body is increased, the thickness of the first sintered body is adjusted in order to obtain a desired emission intensity or a desired color tone. It is necessary to use it thinly. The first sintered body thinned to obtain a desired color tone may not have the desired strength as a wavelength conversion sintered body, and may be difficult to handle. Further, when the content of the α-sialone phosphor with respect to 100% by mass of the mixture constituting the molded product or the total content of the α-sialon phosphor and the rare earth aluminate phosphor exceeds 70% by mass, molding is performed. The amount of phosphor contained in the body is increased, the amount of aluminum oxide is relatively decreased, and the relative wavelength conversion sintered body composed of the first sintered body or the second sintered body described later is obtained. It may be difficult to increase the density.

When the rare earth aluminate phosphor is contained in the mixture, the blending ratio of the α-sialon phosphor and the rare earth aluminate phosphor in the mixture constituting the molded product is desired because the desired emission intensity can be obtained. The amount of the first sintered body that emits light of the above color tone may be obtained, and the content of the α-sialon phosphor is in the range of 0.1% by mass or more and 40% by mass or less with respect to 100% by mass of the mixture. The total content of the α-sialone phosphor and the rare earth aluminate phosphor may be in the range of 0.1% by mass or more and 70% by mass or less. The total content of the α-sialone phosphor and the rare earth aluminate phosphor is in the range of 0.1% by mass or more and 70% by mass or less with respect to 100% by mass of the mixture constituting the molded product, and the α-sialon phosphor If the content of is in the range of 0.1% by mass or more and 40% by mass or less, for example, the mass ratio of α-sialone phosphor to rare earth aluminate phosphor (α-sialon phosphor: rare earth aluminate phosphor) ) Is the mass ratio of the charged material, preferably in the range of 1:99 to 99: 1, more preferably in the range of 2:98 to 98: 2, and further preferably in the range of 3:97 to 95: 5. It may be within the range, and more preferably within the range of 4:96 to 90:10.

The total content of the α-sialone phosphor and the rare earth aluminate phosphor is in the range of 0.1% by mass or more and 70% by mass or less with respect to 100% by mass of the mixture constituting the molded product, and α-sialon. When the content of the phosphor is in the range of 0.1% by mass or more and 40% by mass or less, the content of the rare earth aluminate phosphor is the mass ratio of the charged material, preferably 0.1% by mass or more and 69. It is in the range of 9% by mass or less, more preferably in the range of 0.5% by mass or more and 60% by mass or less, further preferably in the range of 0.8% by mass or more and 50% by mass or less, and further. It is preferably in the range of 1% by mass or more and 40% by mass or less, and particularly preferably in the range of 1% by mass or more and 30% by mass or less. Wavelength conversion to obtain a desired color tone when the content of the rare earth aluminate phosphor is within the range of 0.1% by mass or more and 69.9% by mass or less with respect to 100% by mass of the mixture constituting the molded product. A sintered body can be obtained.

FIG. 1 is a flowchart of a method for manufacturing a wavelength conversion sintered body. The process of the manufacturing method of the wavelength conversion sintered body will be described with reference to FIG. The method for producing the wavelength conversion sintered body includes a molded body preparation step S102 and a primary firing step S103. The method for producing the wavelength-converted sintered body may include a powder mixing step S101 before the molded body preparation step S102, and after the primary firing step S103, a processing step S105 for processing the wavelength-converted sintered body is performed. It may be included.

Powder mixing step In the powder mixing step, α-sialon phosphor powder, aluminum oxide particles, and, if necessary, rare earth aluminate phosphor powder are mixed as powders constituting the molded product. To do. The powder can be mixed using a mortar and a pestle. The powder may be mixed using a mixing medium such as a ball mill. In addition, a molding aid may be used in order to facilitate the mixing of the powder and further facilitate the molding of the mixed powder. Examples of the molding aid include water and ethanol. The molding aid is preferably one that easily volatilizes in the subsequent firing step. It is not necessary to use a molding aid. When the molding aid is added, the amount of the molding aid is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, still more preferably 5 parts by mass or less, based on 100 parts by mass of the mixture.

Molded product preparation step In the molded product preparation step, a mixture containing an α-sialon phosphor, aluminum oxide particles, and, if necessary, a rare earth aluminate phosphor is molded into a desired shape to obtain a molded product. .. As a molding method of the mixture, a known method such as a press molding method can be adopted. For example, a mold press molding method, JIS Z2500: 2000, No. Examples thereof include a cold hydrostatic isotropic pressing method (Cold Isostatic Pressing, hereinafter also referred to as “CIP treatment”) whose term is defined in 2109. As the molding method, two types of methods may be adopted in order to adjust the shape of the molded body, or CIP treatment may be performed after the die press molding. In the CIP treatment, it is preferable to press the molded product using water as a medium.

The pressure during die press molding is preferably in the range of 3 MPa or more and 50 MPa or less, and more preferably in the range of 4 MPa or more and 20 MPa or less. When the pressure at the time of die press molding is within the range of 3 MPa or more and 50 MPa or less, the molded product can be adjusted to a desired shape.

The pressure in the CIP treatment is preferably in the range of 50 MPa or more and 250 MPa or less, and more preferably in the range of 100 MPa or more and 200 MPa or less. When the pressure in the CIP treatment is within the above range, the density of the molded body is increased, and a molded body having a substantially uniform density as a whole can be obtained, which is obtained in the subsequent primary firing step and secondary firing step. The density of the boulders can be increased.

Primary firing step In the primary firing step, a molded product of a mixture containing an α-sialon phosphor, aluminum oxide particles, and, if necessary, a rare earth aluminate phosphor is formed at a temperature within the range of 1370 ° C. or higher and 1600 ° C. or lower. This is a step of primary firing to obtain a first sintered body. By the primary firing step, the sintering density of the α-sialon phosphor contained in the molded body, the aluminum oxide particles, and the rare earth aluminate phosphor contained as necessary is increased, and the scattering of light due to the voids is suppressed. It is possible to obtain a wavelength-converted sintered body that emits excitation light by increasing the translucency and emits light having a desired emission peak wavelength by the excitation light.

The temperature of the primary firing is in the range of 1370 ° C. or higher and 1600 ° C. or lower. When the temperature of the primary firing is less than 1370 ° C. and a small amount of gallium oxide is contained in the mixture, gallium oxide inhibits the sintering of aluminum oxide particles, and voids are formed in the sintered body. The relative density of the first sintered body may be low. In a sintered body having a low relative density, light may be scattered too much in the voids in the sintered body, making it difficult for the light to escape from the sintered body, and the emission intensity of the wavelength-converted sintered body may decrease. When the temperature of the primary firing exceeds 1600 ° C., the α-sialon phosphor reacts with the aluminum oxide particles in the molded body, the crystal structure of the α-sialon phosphor is decomposed, and the obtained first sintered body is obtained. Does not emit light even when irradiated with excitation light. The temperature of the primary firing is preferably in the range of 1380 ° C. or higher and 1590 ° C. or lower, more preferably in the range of 1400 ° C. or higher and 1580 ° C. or lower, and further preferably in the range of 1400 ° C. or higher and 1560 ° C. or lower.

The primary firing is an atmospheric sintering method in which firing is performed in a non-oxidizing atmosphere without applying pressure or load, an atmospheric pressure sintering method in which firing is performed under pressure in a non-oxidizing atmosphere, and hot pressing. Examples thereof include a sintering method and a discharge plasma sintering method (Spark Plasma Sintering, hereinafter also referred to as “SPS”).

The primary firing is preferably performed in an atmosphere containing nitrogen gas. The atmosphere containing nitrogen gas is an atmosphere containing at least 99% by volume or more of nitrogen gas. The nitrogen gas in the atmosphere containing the nitrogen gas is preferably 99% by volume or more, more preferably 99.5% by volume or more. In addition to nitrogen gas, a trace amount of gas such as oxygen may be contained in the atmosphere containing nitrogen gas. The content of oxygen in the atmosphere containing nitrogen gas is preferably 1% by volume or less, more preferably 0.5% by volume or less, still more preferably 0.1% by volume or less, still more preferably 0.01. By volume or less, particularly preferably 0.001 by volume or less. When the atmosphere of the primary firing is an atmosphere containing nitrogen gas, the deterioration of the crystal structure of the α-sialon phosphor in the primary firing is suppressed, and the first sintered body containing the α-sialon phosphor that maintains the crystal structure is produced. Obtainable.

The atmospheric pressure of the primary firing is preferably in the range of 0.2 MPa or more and 200 MPa or less. Atmospheric pressure refers to gauge pressure. The primary firing is preferably performed under an atmospheric pressure in the range of 0.2 MPa or more and 200 MPa or less. The α-sialone phosphor, which is an oxynitride, is more easily decomposed at higher temperatures, but the α-sialon phosphor can be more decomposed by performing the primary firing in a pressurized atmosphere within the range of 0.2 MPa or more and 200 MPa or less. A first sintered body that is suppressed and has a high emission intensity is obtained. The atmospheric pressure is more preferably in the range of 0.2 MPa or more and 1.0 MPa or less, and further preferably in the range of 0.8 MPa or more and 1.0 MPa or less as the gauge pressure.

Secondary firing step In the method for producing a wavelength conversion sintered body, a step of secondary firing the first sintered body obtained after the primary firing to obtain a second sintered body (secondary firing step S104). Is preferably included. FIG. 2 is a flowchart of a method for manufacturing a wavelength conversion sintered body.

Secondary firing is performed by JIS Z2500: 2000, No. Hot isostatic pressing (hereinafter also referred to as “HIP”) treatment, as defined in 2112, is preferably performed at a temperature within the range of 1000 ° C. or higher and 1600 ° C. or lower. If the temperature of the secondary firing is less than 1000 ° C., a second sintered body having a higher relative density than the first sintered body cannot be obtained even if the secondary firing is performed. When the temperature of the secondary firing exceeds 1600 ° C., the α-sialon phosphor reacts with the aluminum oxide particles, and a part of the crystal structure of the α-sialon phosphor is decomposed, resulting in the second sintering. The emission intensity of the body becomes low. The temperature of the secondary firing is more preferably in the range of 1100 ° C. or higher and 1580 ° C. or lower, further preferably in the range of 1200 ° C. or higher and 1570 ° C. or lower, and even more preferably in the range of 1300 ° C. or higher and 1560 ° C. or lower. It is particularly preferably in the range of more than 1350 ° C and not more than 1550 ° C.

The secondary firing is preferably performed in an inert gas atmosphere. The inert gas atmosphere means an atmosphere containing argon, helium, nitrogen or the like as the main components of the atmosphere. Here, the term "argon, helium, nitrogen or the like as the main component in the atmosphere" means that the atmosphere contains at least 50% by volume or more of at least one gas selected from the group consisting of argon, helium and nitrogen. The oxygen content in the inert gas atmosphere is preferably 1% by volume or less, more preferably 0.5% by volume or less, still more preferably 0.1% by volume or less, still more preferably 0.01% by volume. % Or less, particularly preferably 0.001% by volume or less. The inert gas atmosphere may be the same atmosphere as the atmosphere containing nitrogen gas in the primary firing, and the content of nitrogen gas contained in the atmosphere containing nitrogen gas is preferably 99% by volume or more, more preferably 99% by volume or more. It is 99.5% by volume or more. When the atmosphere of the secondary firing is an inert gas atmosphere, the deterioration of the crystal structure of the α-sialon phosphor in the secondary firing is suppressed, and the second sintered body containing the α-sialon phosphor that maintains the crystal structure. Can be obtained.

When the secondary firing is performed by the HIP treatment, the pressure in the HIP treatment is preferably in the range of 50 MPa or more and 300 MPa or less, and more preferably in the range of 80 MPa or more and 200 MPa or less. When the pressure in the HIP treatment is in the range of 50 MPa or more and 300 MPa or less, the entire sintered body can be made uniform and have a higher density without deteriorating the crystal structure of the α-sialon phosphor.

When the secondary firing is performed by the HIP treatment, the time of the HIP treatment is, for example, 0.5 hours or more and 20 hours or less, and preferably 1 hour or more and 10 hours or less.

By further secondary firing the first sintered body in the secondary firing step, a second sintered body having a higher density can be obtained. The second sintered body may have a lower density than the first sintered body. Depending on the temperature of the secondary firing and the content of the α-sialon phosphor in the first sintered body, the closed pores contained in the first sintered body are crushed by the secondary firing, and the second firing is performed. The α-sialon phosphor contained in the first sintered body may be partially decomposed and evaporated to form open pores in the second sintered body, and the first sintered body may have open pores. In some cases, the density is higher than that of the second sintered body. If the density of the first sintered body is higher than that of the second sintered body, it is not necessary to perform secondary firing. Even when Ga is contained in the mixture constituting the molded product in an amount of 15 mass ppm or less, it is presumed that the Ga contained in a small amount by the primary firing is almost evaporated, and in the secondary firing, the mixture is contained. It is considered that it is not affected by Ga contained in a small amount.

Processing Step In the method for producing a wavelength conversion sintered body, a processing step of processing the obtained wavelength conversion sintered body composed of the first sintered body or the second sintered body may be included. The processing step is a step of cutting the obtained wavelength conversion sintered body into a desired thickness and size. The cutting method of the wavelength conversion sintered body can be selected from known methods such as blade dicing, laser dicing, and wire saw. Of these, a wire saw is preferable because the cut surface is flattened with high accuracy. The thickness of the wavelength conversion sintered body is not particularly limited, but is preferably in the range of 1 μm or more and 1 mm or less, and more preferably in the range of 10 μm or more and 800 μm or less in consideration of mechanical strength and light emission intensity. It is more preferably in the range of 50 μm or more and 500 μm or less, and even more preferably in the range of 100 μm or more and 400 μm or less.

Relative Density of First Sintered Body The relative density of the first sintered body is preferably 90% or more, more preferably 91% or more, still more preferably 93% or more, and particularly preferably 94% or more. The relative density of the first sintered body may be 100% or less, and the relative density of the first sintered body may be 99% or less or 98% or less. The formation of voids due to the inhibition of sintering of aluminum oxide particles by a small amount of Ga is suppressed, and the relative density of the first sintered body becomes 90% or more, so that the desired emission peak wavelength can be obtained by irradiation with excitation light. It can be used as a wavelength conversion sintered body having. Further, when the secondary firing is performed after the primary firing, the relative density of the first sintered body is 90% or more, so that the density of the second sintered body is further increased in the secondary firing after the primary firing. Since the number of voids in the wavelength conversion sintered body is reduced and the scattering of light in the voids is suppressed, a wavelength conversion sintered body having high emission intensity can be manufactured.

The relative density of the first sintered body can be obtained from the apparent density of the first sintered body and the true density of the first sintered body. The relative density can be calculated by the following formula (2).

The true density of the first sintered body is calculated by the following formula (3).

The apparent density of the first sintered body is determined from the mass of the first sintered body and the volume of the first sintered body obtained by the Archimedes method. The apparent density of the first sintered body can be calculated by the following formula (4).

Relative Density of Second Sintered Body The second sintered body obtained after the secondary firing has a relative density of preferably 92% or more, more preferably 93% or more, still more preferably 94% or more, and particularly preferably 94% or more. It is 95% or more. As a result, the voids of the wavelength conversion sintered body are small, and the emission intensity can be increased. Further, since the voids are small, it is possible to obtain a wavelength conversion sintered body made of the processed second sintered body without being chipped even if the processing is performed, for example, in the processing process. The relative density of the second sintered body may be 100% or less, and the relative density of the second sintered body may be 99.9% or less or 99.8% or less.

For the relative density of the second sintered body, the first sintered body in the above calculation formulas (2) to (4) for obtaining the relative density of the first sintered body is replaced with the second sintered body. Can be sought.

Wavelength-converted sintered body The obtained first sintered body or second sintered body can be used as the wavelength-converted sintered body. The wavelength conversion sintered body composed of the first sintered body or the second sintered body contains at least an α-sialon phosphor and aluminum oxide, and further contains a rare earth aluminate phosphor. You may be. The wavelength conversion sintered body composed of the first sintered body or the second sintered body preferably contains the α-sialon phosphor in the range of 0.1% by mass or more and 40% by mass or less. When the content of the α-sialon phosphor in the wavelength conversion sintered body is in the range of 0.1% by mass or more and 40% by mass or less, a desired emission intensity can be obtained. The content of the α-sialon phosphor in the wavelength conversion sintered body is determined by elemental analysis of the elements constituting the α-sialon phosphor using ICP-AES, and wavelength conversion baking based on the obtained elemental analysis result. The content of α-sialon phosphor contained in the body can be measured. The α-sialon phosphor contained in the wavelength conversion sintered body preferably has a composition represented by the above formula (I) or (II).

When the wavelength conversion sintered body contains a rare earth aluminate phosphor, the total content of the α-sialon phosphor and the rare earth aluminate phosphor is within the range of 0.1% by mass or more and 70% by mass or less. It is preferable to have. The content of the α-sialon phosphor in the wavelength conversion sintered body is within the range of 0.1% by mass or more and 40% by mass or less, and the total content of the α-sialon phosphor and the rare earth aluminate phosphor is When is in the range of 0.1% by mass or more and 70% by mass or less, light emission of a desired color tone can be obtained by irradiation with excitation light. The rare earth aluminate phosphor in the wavelength conversion section sintered body is subjected to elemental analysis by ICP-AES, and the content of the rare earth aluminate phosphor contained in the wavelength conversion sintered body is obtained from the result of the elemental analysis obtained. Can be measured. The rare earth aluminate phosphor preferably has a composition represented by (Y, Gd, Tb, Lu) ₃ Al ₅ O ₁₂ : Ce, and has a composition represented by the above formula (III) or (IV). It is preferable to have.

The α-sialon phosphor in the wavelength conversion sintered body, aluminum oxide, and the rare earth aluminate phosphor contained as needed are distinguished by grain boundaries because they have different crystal structures. The wavelength conversion sintered body is composed of a first sintered body or a second sintered body, and the relative density is preferably 90% or more, more preferably 91% or more, still more preferably 92% or more, and more. It is more preferably 94% or more, and particularly preferably 95% or more. The relative density of the wavelength-converted sintered body can be obtained by replacing the first sintered body with the wavelength-converted sintered body in the above calculation formulas (2) to (4).

The wavelength conversion sintered body can form a light emitting device by combining with a light emitting element of an LED or LD. The wavelength conversion sintered body converts the excitation light emitted from the light emitting element to emit light having a desired emission peak wavelength, and the light emitting device is wavelength-converted with the light from the light emitting element by the wavelength conversion sintered body. It emits mixed-color light with the light. As the light emitting element, for example, a light emitting element that emits light in the wavelength range of 350 nm or more and 500 nm or less can be used. As the light emitting device, for example, a semiconductor light emitting device 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 device as an excitation light source, it is possible to obtain a stable light emitting device with high efficiency, high linearity of output with respect to input, and resistance to mechanical impact.

LD may be used as a light emitting element. The excitation light emitted from the LD is incident on the wavelength conversion sintered body, and the light obtained by wavelength-converting the excitation light is condensed by a plurality of optical systems such as a lens array, a deflection conversion element, and a color separation optical system. It may be separated into red light, green light, and blue light and modulated according to image information to form color image light. As the light emitting element, the excitation light emitted from the LD may be incident on the wavelength conversion sintered body through an optical system such as a dichroic mirror or a collimating optical system.

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

Production of LAG Fluorescent Material 1 Lutetium oxide (Lu ₂ O ₃ ), cerium oxide (CeO ₂ ), and aluminum oxide (Al ₂ O ₃ ) are weighed and mixed so as to have the desired composition, and the raw material mixture is prepared. Obtained. Barium fluoride (BaF ₂ ) was added to the raw material mixture as the flux, and the raw material mixture and the flux were further mixed by a ball mill. This mixture was placed in an alumina crucible and heat-treated at 1500 ° C. for 10 hours in a reducing atmosphere to obtain a fired product. The fired product is dispersed in pure water, and while vibrating through a sieve, a solvent (pure water) is allowed to flow through a wet sieve, and then dehydrated, dried, and passed through a dry sieve for classification. Then, lutetium aluminum garnet (hereinafter, also referred to as “LAG”) phosphor 1 was obtained. The average particle size of the LAG phosphor 1 (Fisher Sub-Sieve Sizers' number) was measured by the FSSS method described later. The average particle size of the LAG phosphor 1 was 23 μm. The composition of the LAG phosphor was analyzed by the method described later. The LAG phosphor 1 had a composition represented by Lu _2.984 Ce _0.016 Al ₅ O ₁₂ . The amount of Ga in the LAG phosphor 1 was less than 20 mass ppm.

Production of LAG Fluorescent Material 2 The LAG phosphor 2 was produced in the same manner as the LAG phosphor 1. The average particle size of the LAG phosphor 2 measured by the FSSS method was 23 μm. The LAG phosphor 2 had a composition represented by Lu _2.984 Ce _0.016 Al ₅ O ₁₂ . The amount of Ga in the LAG phosphor 2 was 58 mass ppm.

Production of YAG phosphor Weigh yttrium oxide (Y ₂ O ₃ ), gadolinium oxide (Gd ₂ O ₃ ), cerium oxide (CeO ₂ ), and aluminum oxide (Al ₂ O ₃ ) so that they have the desired composition. And mixed to obtain a raw material mixture. Barium fluoride (BaF ₂ ) was added to the raw material mixture as the flux, and the raw material mixture and the flux were further mixed by a ball mill. This mixture was placed in an alumina crucible and heat-treated at 1500 ° C. for 10 hours in a reducing atmosphere to obtain a fired product. The calcined product is dispersed in pure water, and while vibrating through a sieve, a solvent (pure water) is allowed to flow through a wet sieve, and then dehydrated, dried, and passed through a dry sieve for classification. Then, an yttrium aluminum garnet (hereinafter, also referred to as “YAG”) phosphor was obtained. The average particle size of the YAG phosphor measured by the FSSS method was 5 μm. The YAG phosphor had a composition represented by (Y _0.575 Gd _0.400 Ce _0.025 ) ₃ Al ₅ O ₁₂ . The amount of Ga in the YAG phosphor was less than 20 mass ppm.

Measurement of average particle size by FSSS method The rare earth aluminate phosphors (LAG phosphor 1, LAG phosphor 2 and YAG phosphor 1) and aluminum oxide particles used in each example were used as Fisher Sub-Seve Sizer Model 95 (Fisher Scienceific). The average particle size was measured by the FSSS method using (manufactured by the same company).

Composition analysis For the phosphor to be measured, the mass percentage (mass%) of each element excluding oxygen is measured by an inductively coupled plasma emission spectrometer (ICP-AES), and the mass percentage of each element is used to determine the composition of the phosphor. The molar ratio of each element was calculated. For each LAG phosphor and YAG phosphor, the molar ratios of other elements were calculated based on the molar ratio of Al of 5. In addition, the amount of Ga of each LAG phosphor and YAG phosphor was measured. The amount of Ga in LAG phosphor 1 and YAG phosphor was less than 20 mass ppm, which was below the detection limit.

The wavelength conversion sintered bodies (first sintered body or second sintered body) of each of Examples and Comparative Examples described later were measured as follows. The results are shown in Tables 1 to 4.

Volume median diameter by laser diffraction particle size distribution measurement method The α-sialon phosphor used in each example is a laser diffraction particle size distribution measurement method using a laser diffraction particle size distribution measuring device (product name: MASTER SIZER3000, manufactured by MALVERN). The particle size (volume median diameter) at which the cumulative frequency from the small diameter side in the volume-based particle size distribution according to the above reaches 50% was measured.

Measurement of Purity of Aluminum Oxide Particles The purity of aluminum oxide particles used in Examples and Comparative Examples was measured. After measuring the mass of the aluminum oxide particles used in Examples and Comparative Examples, the aluminum oxide particles were fired at 800 ° C. for 1 hour in an air atmosphere, and the organic components and aluminum oxide particles adhering to the aluminum oxide particles absorbed moisture. The water content was removed, and the mass of the aluminum oxide particles after firing was measured. From the mass of the aluminum oxide particles before and after firing, the purity of aluminum oxide of the aluminum oxide particles was determined using the above calculation formula (1).

Measurement of Relative Densities of First Sintered Body and Second Sintered Body The relative densities of the first sintered body of each Example and Comparative Example were determined based on the above calculation formulas (2) to (4). .. In the above formula (3), the true density of the α-sialon phosphor is 3.29 g / cm ³ , the true density of the aluminum oxide particles is 3.98 g / cm ³ , and the true densities of the LAG phosphor 1 and the LAG phosphor 2. Was 6.48 g / cm ³ , and the true density of the YAG phosphor was 4.77 g / cm ³ . In the calculation formulas (2) to (4), the first sintered body is replaced with the second sintered body, and the relative density of the second sintered body is calculated from the calculation formulas (2) to (4). Obtained based on. In the calculation formula (3), the rare earth aluminate phosphor is replaced with the LAG phosphor 1, the LAG phosphor 2, and the YAG phosphor to obtain the true density of the first sintered body or the second sintered body. It was.

Measurement of Relative Emission Intensity In each Example or Comparative Example, a wavelength conversion sintered body composed of a first sintered body or a second sintered body is cut to a thickness of 500 μm using a wire saw to form a sample. did. Using an LED chip made of a nitride semiconductor having an emission peak wavelength of 455 nm as an excitation light source, a sample of a wavelength conversion sintered body is irradiated with light from this LED chip, and the light from the light source is received from each sample. The emission intensity of the emission peak wavelength in the wavelength range of 430 nm or more and 800 nm or less was measured using a spectral fluorescence photometer (manufactured by Nichia Chemical Industry Co., Ltd.). Regarding Examples 1 to 6 described later, the relative emission intensity (relative emission intensity (relative emission intensity) is set to 100% of 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 sintered body of Example 1. %) Was expressed. With respect to Example 7, Comparative Examples 1 and 2, relative emission is performed with 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 sintered body of Example 7 as 100%. Represented the strength (%). With respect to Examples 8 to 13 and Comparative Examples 3 and 4, which will be described later, 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 sintered body of Example 10 is 100%. The relative emission intensity (%) was expressed as. Regarding Examples 14 to 19 described later, the relative emission intensity (relative emission intensity (relative emission intensity) is set to 100% of 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 sintered body of Example 17. %) Was expressed.

Saturation x, y
From the emission spectrum data measured for the wavelength conversion sintered body samples of each example and comparative example, the chromaticity x on the xy color coordinates in the CIE (Commission International de l'eclarage) 1931 color system. , The chromaticity y was obtained.

External Photographs A blackboard was placed in the background, and external photographs of the wavelength-converted sintered bodies of Example 7, Comparative Example 1 and Comparative Example 2 were obtained using a commercially available camera. 3 to 5 show external photographs of samples of wavelength-converted sintered bodies according to Example 7, Comparative Example 1 and Comparative Example 2, respectively.

Example 1
Powder mixing step 1 part by mass (for molded product) of α-sialon phosphor (product name: Aron Bright variety YL-600, manufactured by Denka Co., Ltd.) having a volume median diameter of 13.0 μm measured by the laser diffraction particle size distribution measurement method. 1% by mass of α-sialon phosphor with respect to 100% by mass of the mixture) and aluminum oxide (α-alumina) particles having an average particle size of 0.5 μm measured by the FSSS method (product name: AA03, Sumitomo Chemical Industries, Ltd.) Manufactured by, the purity of aluminum oxide is 99.5% by mass) 99 parts by mass (99% by mass of aluminum oxide particles with respect to 100% by mass of the mixture for the molded product) is weighed and mixed using a dairy pot and a dairy stick. A mixture for the compact was prepared. In Table 1, the content (mass%) of the α-sialon phosphor indicates the mass ratio of the charge to 100% by mass of the mixture for the molded product. With respect to 100% by mass of the mixture for the molded product, the content of aluminum oxide particles is α- in the mixture in the mass ratio of the charge, except for substances contained in the range of 100% by mass (0.01% by mass) or less. The rest excluding the sialone phosphor. In Table 1, the content of the aluminum oxide particles in each example is the balance obtained by subtracting the α-sialon phosphor (mass%) from 100% by mass of the mixture for the molded product. The Ga content in the mixture (referred to as "Ga content in the mixture" in the table) was calculated from the compounding ratio of the α-sialon phosphor and the aluminum oxide particles contained in the mixture. The content of Ga contained in the α-sialon phosphor measured by ICP-AES is less than 20 mass ppm, which is below the detection limit, and the body color of the α-sialon phosphor is not dull, so Ga is not contained. Therefore, the amount of Ga in the mixture was calculated assuming that the content of Ga contained in the α-sialon phosphor was 0 parts by mass ppm. Further, the content of Ga contained in the aluminum oxide particles measured by ICP-AES is less than 5 mass ppm below the detection limit, and the content of Ga contained in the aluminum oxide particles is 0 mass ppm, and Ga in the mixture. The amount was calculated. The ppm in each table is mass ppm.

Mold preparation step The mixture for the molded body was filled in a mold to form a cylindrical molded body having a diameter of 17.0 mm and a thickness of 10 mm at a pressure of 1.8 MPa (200 kgf / cm ² ). The obtained molded product is placed in a packaging container, vacuum-packed, and treated with water at 176 MPa by a cold hydrostatic isotropic pressure pressurization (CIP) device (manufactured by Kobe Steel (KOBELCO)) using water as a pressure medium. Was done.

Primary firing step The obtained molded product is held in a firing furnace (manufactured by Fuji Dempa Kogyo Co., Ltd.) in a nitrogen gas atmosphere (nitrogen: 99% by volume or more) at a temperature of 0.9 MPa and 1500 ° C. for 6 hours for primary firing. The first sintered body was obtained. The content (% by mass) of the α-sialone phosphor and aluminum oxide in the obtained first sintered body is the charge of each of the α-sialon phosphor and aluminum oxide particles with respect to 100% by mass of the mixture for the molded product. Is almost equal to the mass ratio of. The obtained first sintered body was used as a wavelength conversion sintered body.

Examples 2 to 5
A first sintered body was obtained in the same manner as in Example 1 except that the blending ratios of the α-sialon phosphor and the aluminum oxide particles in the mixture were changed as shown in Table 1. The first sintered body was used as a wavelength conversion sintered body.

Example 6
A first sintered body was obtained in the same manner as in Example 1 except that the temperature of the primary firing was changed to 1550 ° C. as shown in Table 1, and the obtained first sintered body had a wavelength. It was a conversion sintered body.

As shown in Table 1, as the wavelength conversion sintered body according to Examples 1 to 6, both the α-sialon phosphor and the aluminum oxide particles did not contain Ga (Ga is 0 mass ppm). Since one sintered body was formed, the relative density was as high as 90% or more. Further, the relative emission intensities of the wavelength-converted sintered bodies according to Examples 2 to 6 were all higher than the relative emission intensities of Example 1.

Example 7
Powder mixing step 15 parts by mass (15% by mass with respect to 100% by mass of the mixture for molding) of LAG phosphor 1 having an average particle size of 23 μm and a Ga content of less than 20% by mass measured by the FSSS method. , 3 parts by mass (100 mass of mixture for molded body) of α-sialon phosphor (product name: Aron Bright variety YL-600, manufactured by Denka Co., Ltd.) having a volume median diameter of 13.0 μm measured by the laser diffraction particle size distribution measurement method. (3% by mass of α-sialon phosphor) and aluminum oxide (α-alumina) particles having an average particle size of 0.5 μm measured by the FSSS method (product name: AA03, manufactured by Sumitomo Chemical Industries, Ltd.) Using 82 parts by mass (purity of aluminum 99.5% by mass) (82% by mass of aluminum oxide particles with respect to 100% by mass of the mixture for the molded product), the temperature of the primary firing was the temperature shown in Table 2. Except for the above, the first sintered body was obtained through the molded body preparation step and the primary firing step in the same manner as in Example 1. With respect to 100% by mass of the mixture for the molded product, the content of the aluminum oxide particles is α- in the mixture in the mass ratio of the charge, except for the substances contained in the range of 100% by mass (0.01% by mass) or less. The remainder excluding the sialone phosphor and the LAG phosphor. The Ga content in the mixture (referred to as "Ga content in the mixture" in the table) was calculated from the compounding ratio of the α-sialon phosphor, the LAG phosphor 1 and the aluminum oxide particles contained in the mixture. The content of Ga contained in the α-sialon phosphor measured by ICP-AES was 0 mass ppm. The content of Ga contained in the aluminum oxide particles measured by ICP-AES was less than 5 mass ppm, which was below the detection limit. In the same manner as in Example 1, the amount of Ga in the mixture was calculated with the content of Ga contained in the α-sialon phosphor and the aluminum oxide particles being 0 mass ppm, respectively. The amount of Ga contained in the LAG phosphor 1 was less than 20 parts by mass ppm. The amount of Ga in the mixture containing 15% by mass of LAG phosphor 1 was calculated to be less than 3% by mass.

Secondary firing step Using the obtained first sintered body, using a hot isotropic pressurization (HIP) device (manufactured by Kobe Steel (KOBELCO)), using nitrogen gas as the pressure medium, nitrogen gas A second sintered body was obtained by secondary firing by HIP treatment for 2 hours at a temperature of 1450 ° C. and a pressure of 195 MPa under an atmosphere (nitrogen: 99% by volume or more). This second sintered body was used as a wavelength conversion sintered body. The contents (% by mass) of the α-sialone phosphor, the LAG phosphor 1 and the aluminum oxide in the obtained second sintered body are the α-sialon phosphor and the LAG with respect to 100% by mass of the mixture for the molded product. It is approximately equal to the mass ratio of each charge of the phosphor and the aluminum oxide particles.

Comparative Example 1
In the powder mixing step, the second sintered body was obtained in the same manner as in Example 7 except that gallium oxide (Ga ₂ O ₃ ) was added so that the content of Ga in the mixture was 50 mass ppm. The second sintered body was used as a wavelength conversion sintered body.

Comparative Example 2
In the powder mixing step, the second sintered body was obtained in the same manner as in Example 7 except that gallium oxide (Ga ₂ O ₃ ) was added so that the content of Ga in the mixture was 200 mass ppm. The second sintered body was used as a wavelength conversion sintered body.

As shown in Table 2, in the wavelength conversion sintered body according to Example 7, the relative density of the first sintered body is 95% or more, and the relative density of the second sintered body is 99.9%. there were. On the other hand, the wavelength conversion sintered bodies according to Comparative Examples 1 and 2 had a considerably lower relative emission intensity than that of Example 7. As the wavelength conversion sintered bodies of Comparative Examples 1 and 2, a mixture containing a large amount of Ga in excess of 15 mass ppm was used. Therefore, when Ga contained in the mixture reacts with the α-sialon phosphor, it changes to an α-sialon phosphor different from the original one, the body color of the wavelength conversion sintered body becomes dull, and the relative density is relatively high. Although it is high, it is presumed that the emission intensity of the wavelength-converted sintered body decreased due to the large influence of the change in body color. Further, the chromaticity x and y of the wavelength-converted sintered bodies of Comparative Examples 1 and 2 are numerical values having different chromaticities x, as compared with the chromaticity x and y of the wavelength-converted sintered body of Example 7. The desired chromaticity was not obtained.

FIG. 3 shows the wavelength conversion sintered body according to Example 7, FIG. 4 shows the wavelength conversion sintered body according to Comparative Example 1, and FIG. 5 shows the wavelength conversion sintered body according to Comparative Example 2 using a wire saw. It is an external photograph of a cut sample. The appearance of the wavelength conversion sintered body according to Comparative Example 1 and Comparative Example 2 was whitish as compared with the appearance of the wavelength conversion sintered body of Example 7, and the body color of the wavelength conversion sintered body was changed. ..

Examples 8 to 10
The compounding ratios of the LAG phosphor 1, α-sialon phosphor, and aluminum oxide particles in the mixture were changed as shown in Table 3, except that the primary firing was performed at 1450 ° C and the secondary firing was performed at 1400 ° C. In the same manner as in Example 7, a second sintered body was obtained, and the second sintered body was used as a wavelength conversion sintered body.

Examples 11 to 13
Using the LAG phosphor 2 having an average particle size of 23 μm and a Ga content of 58 mass ppm measured by the FSSS method, the blending ratio of the LAG phosphor 2, the α-sialon phosphor, and the aluminum oxide particles in the mixture. And, except that the temperature of the primary firing and the temperature of the secondary firing were changed as shown in Table 3, a second sintered body was obtained in the same manner as in Example 7, and the second sintered body was obtained. Was used as a wavelength conversion sintered body.

Comparative Examples 3 and 4
Using the LAG phosphor 2 having an average particle size of 23 μm and a Ga content of 58 mass ppm measured by the FSSS method, the blending ratio of the LAG phosphor 2, the α-sialon phosphor, and the aluminum oxide particles in the mixture. And, except that the temperature of the primary firing and the temperature of the secondary firing were changed as shown in Table 3, a second sintered body was obtained in the same manner as in Example 7, and the second sintered body was obtained. Was used as a wavelength conversion sintered body.

As shown in Table 3, in the wavelength conversion sintered bodies according to Examples 8 to 13, the relative density of the first sintered body is 94% or more, and the relative density of the second sintered body is the first. A wavelength conversion sintered body having a higher relative density than that of the sintered body of No. 1 was obtained. In the wavelength conversion sintered body according to Example 10, the relative density of the second sintered body was lower than that of Examples 8 to 9 and Examples 11 to 13. The wavelength conversion sintered body according to Example 10 has a Ga content of 12 mass ppm in the mixture, and has a higher Ga content than Examples 8 to 9 and Examples 11 to 13, so that the aluminum oxide particles It was speculated that the sintering was inhibited by Ga and more voids were formed. In the wavelength conversion sintered body according to Example 13, the relative density of the first sintered body was lower than that in Examples 11 to 12. In the wavelength conversion sintered body according to Example 13, since the temperature of the primary firing was lower than that of Examples 11 to 12, the sintering of aluminum oxide did not proceed as compared with Examples 11 and 12, so that the first It is presumed that the relative density of the sintered body was low, and even if the secondary firing was performed by HIP treatment, the relative density could not be increased and the relative density became low. Since the wavelength conversion sintered body according to Example 13 has a low relative density, it is presumed that the incident light is scattered and the relative emission intensity is lower than that of Examples 11 and 12.

In the wavelength conversion sintered body according to Comparative Example 3, the Ga content in the mixture was as high as 17 mass ppm, and the temperature of the primary firing was lower than in Examples 8 to 12, so that the sintering of aluminum oxide was hindered. Even when the secondary firing was performed at the same temperature as in Examples 8 to 13, the relative density of the obtained second sintered body was as low as less than 90%. In the wavelength conversion sintered body according to Comparative Example 4, the temperature of the primary firing is 1350 ° C., which is lower than the temperature of the primary firing of Comparative Example 3, so that the sintering of aluminum oxide particles is contained in a small amount of 6 mass ppm in the mixture. By being inhibited by Ga, many voids were formed in the obtained first sintered body. Therefore, even if the secondary firing by the HIP treatment was performed, the relative density did not increase, and the relative densities of the first sintered body and the second sintered body became the same. Since the wavelength conversion sintered body according to Comparative Examples 3 and 4 has a low relative density of less than 90%, the excitation light is scattered in the voids in the sintered body, or the excitation light incidented by the voids is the sintered body. Get out of. Therefore, the efficiency of wavelength conversion by the phosphor is lowered, and the relative emission intensity is considerably lower than 50% as compared with the wavelength conversion sintered body according to Examples 8 to 13.

Examples 14-19
Instead of the LAG phosphor 1 or the LAG phosphor 2, a YAG phosphor having an average particle size of 5 μm and a Ga content of less than 20 mass ppm measured by the FSSS method was used to prepare the YAG phosphor in the mixture. A first sintered body was obtained in the same manner as in Example 7 except that the compounding ratio of the α-sialon phosphor and the aluminum oxide particles and the temperature of the primary firing were changed as shown in Table 4. , The first sintered body was a wavelength conversion sintered body. With respect to 100% by mass of the mixture for the molded product, the content of aluminum oxide particles is α- in the mixture in the mass ratio of the charge, except for substances contained in the range of 100% by mass (0.01% by mass) or less. The remainder excluding the sialon phosphor and the YAG phosphor.

As shown in Table 4, the wavelength conversion sintered bodies according to Examples 14 to 19 had a relative density of 90% or more of the first sintered body, and a wavelength conversion sintered body having a high relative density was obtained. ..

The wavelength conversion sintered body according to the present disclosure can be used as a wavelength conversion member capable of converting the wavelength of light emitted from an LED or LD.

Claims (15)

To prepare a molded product of a mixture containing an α-sialon phosphor and aluminum oxide particles and having a Ga content of 15 mass ppm or less.
A method for producing a wavelength conversion sintered body, which comprises primary firing the molded body at a temperature in the range of 1370 ° C. or higher and 1600 ° C. or lower to obtain a first sintered body. The method for producing a wavelength-converted sintered body according to claim 1, wherein the content of Ga contained in the mixture is 10 mass ppm or less. The method for producing a wavelength-converted sintered body according to claim 1 or 2, wherein the mixture contains a rare earth aluminate phosphor. A claim comprising obtaining a second sintered body by secondary firing the first sintered body at a temperature in the range of 1000 ° C. or higher and 1600 ° C. or lower by hot isotropic pressure pressurization (HIP) treatment. Item 8. The method for producing a wavelength conversion sintered body according to any one of Items 1 to 3. The production of the wavelength conversion sintered body according to any one of claims 1 to 4, wherein the volume median diameter measured by the laser diffraction particle size distribution measurement method of the α-sialon phosphor is within the range of 2 μm or more and 30 μm or less. Method. The wavelength conversion sintered body according to any one of claims 1 to 5, wherein the average particle size of the aluminum oxide particles measured by the Fisher subsieving sizer method is in the range of 0.1 μm or more and 1.3 μm or less. Production method. The production of the wavelength conversion sintered body according to any one of claims 3 to 6, wherein the average particle size of the rare earth aluminate phosphor measured by the Fisher subsieving sizer method is within the range of 1 μm or more and 50 μm or less. Method. The mixture contains the α-sialone phosphor in the range of 0.1% by mass or more and 40% by mass or less with respect to 100% by mass of the mixture, and excludes the α-sialon phosphor from 100% by mass of the mixture. The wavelength conversion sintered body according to any one of claims 1 to 7, wherein the balance is the aluminum oxide particles, and the aluminum oxide particles are contained in the range of 60% by mass or more and 99.9% by mass or less. Production method. The mixture contains the total amount of the α-sialon phosphor and the rare earth aluminate phosphor in the range of 0.1% by mass or more and 70% by mass or less with respect to 100% by mass of the mixture, and the mixture 100 The remainder excluding the α-sialon phosphor and the rare earth aluminate phosphor from mass% is the aluminum oxide particles, and the aluminum oxide particles are contained in the range of 30% by mass or more and 99.9% by mass or less. The method for producing a wavelength-converted sintered body according to any one of claims 3 to 7. The method for producing a wavelength-converted sintered body according to any one of claims 1 to 9, wherein the α-sialon phosphor has a composition represented by the following formula (I).
M _k Si _{12- (m + n)} Al _{m + n On} N _16-n : Eu (I)
(In formula (I), M is at least one element selected from the group consisting of Li, Mg, Ca, Sr, Y and lanthanoid elements (excluding La and Ce), and k, m, n is a number that satisfies 0 <k ≦ 2.0, 2.0 ≦ m ≦ 6.0, and 0 ≦ n ≦ 1.0.) The rare earth aluminate phosphor comprises a rare earth aluminate phosphor having a composition represented by the following formula (III) and a rare earth aluminate phosphor having a composition represented by the following formula (IV). The method for producing a wavelength-converted sintered body according to any one of claims 3 to 10, which is at least one selected from the group.
(Y _1-ab Gd _a Ce _b ) ₃ Al ₅ O ₁₂ (III)
(In formula (III), a and b are numbers satisfying 0 ≦ a ≦ 0.500 and 0 <b ≦ 0.030.)
(Lu _1-c Ce _c ) ₃ Al ₅ O ₁₂ (IV)
(In formula (IV), c is a number satisfying 0 <c ≦ 0.100.) The method for producing a wavelength conversion sintered body according to any one of claims 1 to 11, wherein the mixture is molded at a pressure of 3 MPa or more and 50 MPa or less using a die press to obtain the molded product. The method for producing a wavelength-converted sintered body according to any one of claims 1 to 12, wherein the mixture is subjected to cold isotropic pressure treatment at a pressure of 50 MPa or more and 250 MPa or less to obtain the molded product. The method for producing a wavelength-converted sintered body according to any one of claims 1 to 13, wherein the purity of aluminum oxide of the aluminum oxide particles is 99.0% by mass or more. The method for producing a wavelength-converted sintered body according to any one of claims 1 to 14, wherein the relative density of the first sintered body is 90% or more.