阅读说明：本技术 陶瓷复合体、使用了其的发光装置和陶瓷复合体的制造方法 (Ceramic composite, light-emitting device using same, and method for producing ceramic composite ) 是由 近藤匡毅 真岛康彰 于 2019-06-12 设计创作，主要内容包括：本发明提供一种发光特性高的陶瓷复合体。陶瓷复合体为包含稀土类铝酸盐荧光体、玻璃和氟化钙的陶瓷复合体,将它们的合计量设为100体积％,稀土类铝酸盐荧光体的含量为15体积％以上且60体积％以下,玻璃的含量为3体积％以上且84体积％以下,氟化钙的含量为1体积％以上且60体积％以下。(The invention provides a ceramic composite having high light-emitting characteristics. The ceramic composite is a ceramic composite comprising a rare earth aluminate phosphor, glass and calcium fluoride, and the total amount of these is 100 vol%, the rare earth aluminate phosphor is contained in an amount of 15 vol% or more and 60 vol% or less, the glass is contained in an amount of 3 vol% or more and 84 vol% or less, and the calcium fluoride is contained in an amount of 1 vol% or more and 60 vol% or less.)

1. A ceramic composite comprising a rare earth aluminate phosphor, a glass and calcium fluoride, wherein the total amount of the rare earth aluminate phosphor is 100 vol%, the rare earth aluminate phosphor is contained in an amount of 15 vol% or more and 60 vol% or less, the glass is contained in an amount of 3 vol% or more and 84 vol% or less, and the calcium fluoride is contained in an amount of 1 vol% or more and 60 vol% or less.

2. The ceramic composite according to claim 1, which is a plate-like body having a first main surface and a second main surface, and has a plate thickness of 90 μm or more and 300 μm or less,

the first main surface serves as a light incident surface, and the second main surface is located on the opposite side of the first main surface and serves as a light emitting surface.

3. The ceramic composite according to claim 1 or 2, wherein the average particle size of the rare earth aluminate phosphor is 15 μm or more and 40 μm or less.

4. The ceramic composite according to any one of claims 1 to 3, wherein the rare earth aluminate phosphor has a composition represented by the following formula (I),

(Ln_1-aCe_a)₃(Al_cGa_b)₅O₁₂ (I)

in the formula (I), Ln is at least 1 selected from Y, Gd, Lu and Tb, and a, b and c are numbers satisfying 0 & lta & lt 0.022, 0 & ltb & lt 0.4, 0 & ltc & lt 1.1, 0.9 & lt b + c & lt 1.1.

5. The ceramic composite according to any one of claims 2 to 4, wherein a ratio of an optical path of outgoing light emitted from the second main surface to an optical path of incident light incident on the first main surface is in a range of 0.400 or more and 0.990 or less.

6. A light-emitting device is provided with:

the ceramic composite body according to any one of claims 1 to 5; and

a light source for emitting light for exciting the rare earth aluminate phosphor.

7. The light emitting device of claim 6, wherein the light source is a semiconductor laser.

8. A method of making a ceramic composite, comprising: preparing a molded body and firing the molded body,

the molded body contains a rare earth aluminate phosphor, a glass, and calcium fluoride, and the content of the rare earth aluminate phosphor is 15 vol% or more and 60 vol% or less, the content of the glass is 3 vol% or more and 84 vol% or less, and the content of the calcium fluoride is 1 vol% or more and 60 vol% or less, based on the total amount of the rare earth aluminate phosphor, the glass, and the calcium fluoride.

9. The method for producing a ceramic composite according to claim 8, wherein the firing temperature is in a range of 800 ℃ to 1100 ℃.

10. The method of manufacturing a ceramic composite body according to claim 8 or 9, comprising: the molded body is fired in an atmosphere containing 5 vol% or more of oxygen.

11. The method for producing a ceramic composite according to any one of claims 8 to 10, wherein the average particle size of the rare earth aluminate phosphor is 15 μm or more and 40 μm or less.

12. The method for producing a ceramic composite according to any one of claims 8 to 11, wherein the composition of the rare earth aluminate phosphor is represented by the following formula (I),

(Ln_1-aCe_a)₃(Al_cGa_b)₅O₁₂ (I)

in the formula (I), Ln is at least 1 selected from Y, Gd, Lu and Tb, and a, b and c are numbers satisfying 0 & lta & lt 0.022, 0 & ltb & lt 0.4, 0 & ltc & lt 1.1, 0.9 & lt b + c & lt 1.1.

Technical Field

The present invention relates to a ceramic composite, a light-emitting device using the same, and a method for manufacturing the ceramic composite.

Background

A ceramic composite including a phosphor that converts the wavelength of Light emitted from a Light Emitting element such as a Light Emitting Diode (hereinafter also referred to as an "LED") or a Laser Diode (hereinafter also referred to as an "LD") is used in, for example, a Light Emitting device used for an in-vehicle application, a general illumination application, a backlight of a liquid crystal display device, a projector, and the like.

Examples of the phosphor for converting light from the light emitting element include a rare earth aluminate phosphor containing a rare earth element such as yttrium or lutetium. As a ceramic composite containing these inorganic phosphors, for example, patent document 1 discloses a sintered body in which an inorganic phosphor is dispersed in glass having a softening point higher than 500 ℃.

Disclosure of Invention

Problems to be solved by the invention

However, the sintered body disclosed in patent document 1 is required to be further improved in light emission characteristics (for example, light emission efficiency) when the wavelength of light emitted from a light emitting element such as an LED or an LD is converted.

Accordingly, an object of one embodiment of the present invention is to provide a ceramic composite having improved light emission characteristics, a light-emitting device using the same, and a method for manufacturing the ceramic composite.

Means for solving the problems

The ceramic composite of the present invention is a ceramic composite including a rare earth aluminate phosphor, a glass, and calcium fluoride, and the total amount of these is 100 vol%, the content of the rare earth aluminate phosphor is 15 vol% or more and 60 vol% or less, the content of the glass is 3 vol% or more and 84 vol% or less, and the content of the calcium fluoride is 1 vol% or more and 60 vol% or less.

The light-emitting device of the present invention comprises the above-described ceramic composite and a light source that emits light that excites the above-described rare earth aluminate phosphor.

The method for producing a ceramic composite of the present invention includes: a molded body is prepared and fired, wherein the molded body contains a rare earth aluminate phosphor, a glass and calcium fluoride, and the content of the rare earth aluminate phosphor is 15 vol% or more and 60 vol% or less, the content of the glass is 3 vol% or more and 84 vol% or less, and the content of the calcium fluoride is 1 vol% or more and 60 vol% or less, based on the total amount of the rare earth aluminate phosphor, the glass and the calcium fluoride.

ADVANTAGEOUS EFFECTS OF INVENTION

According to one embodiment of the present invention, a ceramic composite having high light emission characteristics, a light-emitting device using the same, and a method for manufacturing the ceramic composite can be provided.

Drawings

FIG. 1 is a flowchart showing a method for producing a ceramic composite according to the present invention.

Fig. 2 is a luminescence spectrum showing a relationship between a distance from a center of measurement and a relative luminescence intensity in the ceramic composite described in example 3 and comparative example 1.

Fig. 3 is an SEM photograph showing the distribution of fluorine by EDX analysis of the ceramic composite body described in example 3.

Fig. 4 is an SEM photograph showing calcium distribution based on EDX analysis of the ceramic composite body described in example 3.

Detailed Description

The ceramic composite, the light-emitting device using the same, and the method for manufacturing the ceramic composite according to the present embodiment will be described below. 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 ceramic composite, a light-emitting device using the same, and a method for manufacturing the ceramic composite. 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 based on JIS Z8110.

Ceramic composite body

The ceramic composite comprises a rare earth aluminate phosphor, a glass and calcium fluoride, and the total amount of these is 100 vol%, the rare earth aluminate phosphor is contained in an amount of 15 vol% or more and 60 vol% or less, the glass is contained in an amount of 3 vol% or more and 84 vol% or less, and the calcium fluoride is contained in an amount of 1 vol% or more and 60 vol% or less.

The ceramic composite comprises glass as a base material, a rare earth aluminate phosphor and calcium fluoride. Since the ceramic composite contains 1 vol% or more and 60 vol% or less of calcium fluoride in the glass serving as the substrate, light incident on the ceramic composite is scattered into the interior of the ceramic composite due to the calcium fluoride having a smaller refractive index than the glass serving as the substrate, and the escape of the incident light to the outside of the ceramic composite is suppressed. The ceramic composite contains calcium fluoride and a rare earth aluminate phosphor in a glass as a base material. Therefore, light scattered by calcium fluoride is repeatedly scattered inside the ceramic composite, and thus the light is efficiently wavelength-converted by the rare earth aluminate phosphor and emitted to the outside of the ceramic composite, thereby improving the light emission efficiency. In addition, the ceramic composite can emit light condensed in a direction substantially perpendicular to the emission surface by scattering the light incident on the ceramic composite by calcium fluoride contained in the base material, and can condense the light emitted from the ceramic composite to a target position.

The content of the rare earth aluminate phosphor in the ceramic composite is 15 vol% or more and 60 vol% or less, preferably 16 vol% or more, more preferably 17 vol% or more, and still more preferably 18 vol% or more, with the total amount of the rare earth aluminate phosphor, the glass, and the calcium fluoride being 100 vol%. By setting the content of the rare earth aluminate phosphor in the ceramic composite to 15 vol% or more and 60 vol% or less, a ceramic composite having a desired luminous efficiency and a desired relative density can be obtained.

The total amount of the rare earth aluminate phosphor, the glass, and the calcium fluoride is set to 100 vol%, and the content of the calcium fluoride in the ceramic composite is 1 vol% or more and 60 vol% or less, preferably 2 vol% or more and 58 vol% or less, more preferably 3 vol% or more and 55 vol% or less, and still more preferably 5 vol% or more and 50 vol% or less. When the content of calcium fluoride in the ceramic composite is 1 vol% or more and 60 vol% or less, incident light can be scattered to obtain a ceramic composite having high luminous efficiency.

The content of the glass in the ceramic composite is not particularly limited as long as the total amount of the rare earth aluminate phosphor, the glass and the calcium fluoride is 100 vol%, and the rare earth aluminate phosphor is 15 vol% to 60 vol%, and the calcium fluoride is 1 vol% to 60 vol%, but the glass may be included so that the total amount of the rare earth aluminate phosphor, the glass and the calcium fluoride does not exceed 100 vol%. When the glass content of the ceramic composite is 3 vol% or more and 84 vol% or less, a stable base material is formed by the glass, and a ceramic composite having high luminous efficiency and excellent durability can be obtained. The content of the glass in the ceramic composite is preferably 5 vol% or more and 82 vol% or less, more preferably 10 vol% or more and 80 vol% or less, and still more preferably 12 vol% or more and 77 vol% or less.

The relative density of the ceramic composite is preferably 90% or more and 100% or less. Since the relative density of the ceramic composite is 90% or more and 100% or less, the transmittance of light that is efficiently wavelength-converted by the rare earth aluminate phosphor is high, and the light extraction efficiency is high.

Relative density of ceramic composite

The relative density of the ceramic composite is a value calculated from the apparent density of the ceramic composite relative to the true density of the ceramic composite. The relative density was calculated by the following formula (1).

[ mathematical formula 1]

Relative density (%) of ceramic composite (apparent density of ceramic composite ÷ true density of ceramic composite) × 100(1)

The true density of the ceramic composite was calculated as follows: the mass ratio (% by mass) of the glass contained in the ceramic composite was denoted as G_mThe true density (g/cm) of the glass³) Notation G_dThe mass ratio (% by mass) of the rare earth aluminate phosphor is denoted by P_mThe true density (g/cm) of the rare earth aluminate phosphor is determined³) Notation P_dThe mass ratio (mass%) of calcium fluoride is denoted as C_mCalcium fluorideTrue density (g/cm)³) Notation C_dThe time is calculated by the following formula (2).

[ mathematical formula 2]

The mass ratio (mass%) of the rare earth aluminate phosphor: p_m

True density (g/cm) of rare earth aluminate phosphor³)：P_d

The mass ratio (mass%) of the glass: g_m

True density (g/cm) of glass³)：G_d

Calcium fluoride (CaF)₂) The mass ratio (mass%) of: c_m

Calcium fluoride (CaF)₂) True density (g/cm)³)：C_d

G_m+P_m+C_m＝100

The apparent density of the ceramic composite is the mass (g) of the ceramic composite divided by the volume (cm) of the ceramic composite determined by the Archimedes method³) The resulting value. The apparent density of the ceramic composite was calculated by the following formula (3).

[ mathematical formula 3]

Apparent density of ceramic composite (g) mass of ceramic composite ÷ volume of ceramic composite (archimedean method) (cm)³) (3)

The ceramic composite is preferably a plate-like body having a first main surface which is a light incident surface and a second main surface which is located on the opposite side of the first main surface and which is a light emitting surface, and has a plate thickness of 90 μm or more and 300 μm or less. Thus, the incident light and the light wavelength-converted by the rare earth aluminate phosphor are scattered by calcium fluoride contained in the ceramic composite, and the light extraction efficiency can be improved or the mechanical strength can be maintained. The plate thickness of the ceramic composite body as a plate-like body is more preferably 95 μm or more and 250 μm or less, and still more preferably 100 μm or more and 200 μm or less.

The ratio of the optical path of the outgoing light from the second main surface to the optical path of the incident light entering the first main surface (optical path of the outgoing light/optical path of the incident light) of the ceramic composite is preferably 0.400 or more and 0.990 or less, more preferably 0.450 or more and 0.985 or less, further preferably 0.500 or more and 0.980 or less, further preferably 0.550 or more and 0.975 or less, and particularly preferably 0.600 or more and 0.970 or less. When the ratio of the optical path of the outgoing light emitted from the second main surface to the optical path of the incident light entering the first main surface of the ceramic composite (hereinafter, also referred to as "optical path ratio (outgoing light/incident light)") is 0.400 or more and 0.990 or less, the light emitted from the ceramic composite can be condensed toward the target position. The optical path of the incident light entering the first main surface of the ceramic composite is the optical path of the light emitted from the light source. The optical path of the incident light can be measured by, for example, a color luminance meter. The optical path of the incident light is preferably 1mm or more and 5mm or less, and more preferably 2mm or more and 4mm or less. The optical path of the outgoing light from the second main surface of the ceramic composite can be measured as follows: the luminance of light emitted from the ceramic composite was measured by a color luminance meter, the position showing the maximum luminance in the obtained emission spectrum was taken as the center (measurement center), the distance (mm) from the measurement center at two positions reaching a luminance which is one percent of the maximum luminance (hereinafter sometimes referred to as "1/100 luminance") in the emission spectrum was measured as an absolute value, and the sum of the absolute values of the distances (mm) from the measurement center at two positions reaching 1/100 luminance which is the maximum luminance from the maximum luminance was taken as the optical path of the emitted light emitted from the second main surface.

Rare earth aluminate phosphor

The average particle size of the rare earth aluminate phosphor is preferably 15 μm or more and 40 μm or less, more preferably 18 μm or more and 38 μm or less, and still more preferably 20 μm or more and 35 μm or less. This enables efficient wavelength conversion of light incident on the ceramic composite, and improves the light emission efficiency. In addition, the phosphor can be uniformly arranged in the ceramic composite. The average particle diameter of the rare earth aluminate phosphor can be measured by Fisher sub-Sieve sizer (hereinafter also referred to as "FSSS method")") and the average particle size determined by the FSSS method is also referred to as Fisher-Sieve sizer's No. The FSSS method is a method of determining the particle size by measuring the specific surface area by the air permeation method using the flow resistance of air. Specifically, a sample of 1cm was measured under an atmosphere of 25 ℃ and 70% RH by Fisher Scientific Co., Ltd, using a Fisher Scientific model 95³A certain amount of a sample (rare earth aluminate phosphor) was packed in a dedicated tubular container, and then dry air of a constant pressure was passed through the container, and the specific surface area was read from the differential pressure, and the average particle diameter was calculated by the FSSS method.

The rare earth aluminate phosphor preferably has a composition represented by the following formula (I).

(Ln_1-aCe_a)₃(Al_cGa_b)₅O₁₂ (I)

In the formula (I), Ln is at least 1 rare earth element selected from Y, Gd, Lu and Tb, and may contain 2 or more rare earth elements. a. b and c are numbers satisfying 0 < a < 0.022, 0 < b < 0.4, 0 < c < 1.1, and 0.9 < b + c < 1.1.

Ce is an activating element of the phosphor, and the product of the variables a and 3 represents the molar ratio of Ce in the composition represented by formula (I). The "molar ratio" refers to the molar amount of each element in 1 mole of the chemical composition of the rare earth aluminate phosphor. The variable a is more preferably 0.00005 to 0.021 (0.005 × 10)^-2A is not more than 0.021), more preferably not less than 0.0001 but not more than 0.020 (0.01X 10)^-2A is less than or equal to 0.020). The product of the variable b and 5 represents the molar ratio of Ga. In order to convert the desired particle diameter and wavelength into a desired color tone, the variable b may be 0.00001 to 0.35 (0.001 × 10)^-2B is not more than 0.35), and may be not less than 0.00005 and not more than 0.30 (0.005X 10)^-2B is not less than 0.30). The product of the variable c and 5 represents the molar ratio of Al. The variable c is preferably 0.5 or more and 1.1 or less (0.5. ltoreq. c.ltoreq.1.1), more preferably 0.6 or more and 1.0 or less (0.6. ltoreq. c.ltoreq.1.0). The sum of the variable b and the variable c is preferably 0.9 or more and 1.1 or less (0.9. ltoreq. b + c. ltoreq.1.1), and more preferably 0.95 or more and 1.10 or less (0.95. ltoreq. b + c. ltoreq.1.10).

Glass

The softening point of the glass contained in the ceramic composite is preferably 500 ℃ or higher, more preferably 600 ℃ or higher, and still more preferably 700 ℃ or higher. As a raw material of the glass constituting the ceramic composite substrate, glass powder is preferable. When the glass is a glass powder having a softening point of 500 ℃ or higher as a raw material of the ceramic composite, the glass does not react with the rare earth aluminate phosphor when the raw materials are mixed and fired at a temperature of 800 to 1200 ℃ to obtain the ceramic composite, and the change in the body color of the obtained ceramic composite and the blackening can be suppressed, and the decrease in the luminous efficiency can be suppressed. Further, if the glass has a softening point of 500 or more, the durability of the ceramic composite obtained by mixing and firing the rare earth aluminate phosphor and calcium fluoride can be maintained. That is, even when the ceramic composite is left in an environment with a large amount of moisture, the surface of the ceramic composite is prevented from being denatured, and the luminous efficiency can be prevented from being lowered while maintaining the transmittance. The upper limit of the softening point of the glass contained in the ceramic composite is not particularly limited, but the softening point is preferably 1200 ℃ or lower, and more preferably 1100 ℃ or lower.

The type of glass is not limited as long as it has a softening point of 500 or more. Examples of the glass include borosilicate glass. Examples of borosilicate glass include barium borosilicate glass and aluminoborosilicate glass. The glass preferably does not contain components which are liable to react with the components constituting the rare earth aluminate phosphor and which cause discoloration or coloration of the glass due to the reaction, for example, components of Pb, Bi, Fe, Mn or Ce. Even if the above components are contained, the total amount of the components may be allowed to be 10000ppm or less in terms of oxides.

Calcium fluoride

The purity of calcium fluoride contained in the ceramic composite is 99.0 mass% or more, and the purity of calcium fluoride is preferably 99.5 mass% or more. In the ceramic composite, when the ceramic composite contains calcium fluoride having a purity of 99.0 mass% or more, light incident on the ceramic composite and light wavelength-converted by the rare earth aluminate phosphor are scattered, and thus the luminous efficiency can be improved. In addition, calcium fluoride has low reactivity with the rare earth aluminate phosphor when fired into the ceramic composite. Therefore, the rare earth aluminate phosphor is less deteriorated, and a ceramic composite having high luminous efficiency and durability can be obtained. The calcium fluoride may be a single crystal in which the purity of the calcium fluoride is 99.0 mass% or more. In addition, the calcium fluoride may be in the form of powder.

Method for producing ceramic composite

FIG. 1 is a flowchart showing an example of a method for producing a ceramic composite according to the present invention. The steps of the method for producing a ceramic composite will be described with reference to fig. 1. The method for manufacturing a ceramic composite includes a molding preparation step S102 and a firing step S103. The method for manufacturing a ceramic composite may include the powder mixing step S101 before the compact preparation step S102, may include the rough surface treatment step S104 of performing rough surface treatment on the surface of the ceramic composite after the firing step S103, and may further include the machining step S105 of cutting the ceramic composite into a desired size or thickness. The order of the rough surface treatment step S104 and the machining step S105 may be the machining step S105 performed after the rough surface treatment step S104, or the rough surface treatment step S104 may be performed after the machining step S105 in the reverse order.

Powder mixing step

In the powder mixing step, the powders constituting the molded body are mixed. The powder constituting the compact is preferably a powder containing rare earth aluminate phosphor particles, glass powder and calcium fluoride. The powder can be mixed using a mortar and a pestle. The powder may be mixed by using a mixing medium such as a ball mill. In addition, a small amount of a forming aid such as water or ethanol may be used to facilitate mixing of the powder and further to facilitate forming of the mixed powder. The forming aid is preferably a forming aid which is easily volatilized in the subsequent firing step, and when the forming aid is added, the forming aid is preferably 10% by volume or less, more preferably 8% by volume or less, and further preferably 5% by volume or less with respect to 100% by volume of the powder.

Preparation of molded article

In the compact preparation step, a mixed powder is obtained, which contains a rare earth aluminate phosphor, a glass, and calcium fluoride, and in which the content of the rare earth aluminate phosphor is 15 vol% or more and 60 vol% or less, the content of the glass is 3 vol% or more and 84 vol% or less, and the content of the calcium fluoride is 1 vol% or more and 60 vol% or less, based on the total amount of these. The mixed powder is molded into a desired shape to obtain a molded body. The powder can be molded by a known method such as press molding, and examples thereof include die press molding and Cold Isostatic Press (CIP). In order to adjust the shape of the molded article, two molding methods may be used, or CIP may be performed after the press molding of a mold. In CIP, the molded body is preferably pressurized by a hydrostatic pressure method such as cold or the like using water as a medium.

The load at the time of press molding of the mold is preferably 0.1kg/cm²～1.0kg/cm²More preferably 0.2kg/cm²～0.5kg/cm². If the load during the press molding of the mold is in the above range, the molded body can be adjusted to a desired shape.

The pressure in the CIP treatment is preferably 50MPa to 200MPa, more preferably 50MPa to 180 MPa. When the pressure in the CIP treatment is in the above range, the rare earth aluminate phosphor, the glass and the calcium fluoride are mixed so that the relative density of the ceramic composite obtained after firing is preferably 90% to 100%, whereby a compact in which these particles are in contact with each other can be obtained.

Firing Process

The firing step is a step of firing the molded body to obtain a ceramic composite. The molded body is preferably fired in an atmosphere containing 5 vol% or more of oxygen. The oxygen content in the atmosphere is more preferably 10% by volume or more, and still more preferably 15% by volume or more, and may be an atmosphere (oxygen content of 20% by volume or more). By firing the molded body in an atmosphere containing 5 vol% or more of oxygen, the components in the molded body are fired in a state of being closely adhered to each other, and a ceramic composite body having a relative density of preferably 90% or more and 100% or less can be obtained.

The firing temperature is preferably in the range of 800 ℃ to 1100 ℃, and more preferably in the range of 850 ℃ or higher. When the firing temperature is 800 ℃ or higher, a ceramic composite having a relative density of 90% or more and 100% or less can be obtained. Further, when the firing temperature is 1100 ℃ or lower, the glass is softened and the glass is used as a base material, whereby a ceramic composite in which the rare earth aluminate phosphor and calcium fluoride are contained in the base material without melting can be obtained.

Rough surface treatment process

The roughening treatment step is a step of roughening the surface of the obtained ceramic composite. The roughening treatment step may be performed before or after the machining step of cutting the ceramic composite into a desired size or thickness. The ceramic composite subjected to the roughening treatment is preferably a plate-like body having a first main surface which becomes an incident surface of light and a second main surface which is located on the opposite side of the first main surface and which becomes an exit surface of light, and the roughening treatment is preferably performed on the second main surface. Examples of the rough surface treatment method include a method by sandblasting, a method by rough grinding using rough diamond grit, a method by cutting, and a method by chemical etching.

Working procedure

The machining step is a step of cutting and machining the obtained ceramic composite into a desired size or thickness. The cutting method may be a known method, and examples thereof include blade cutting, laser cutting, and cutting with a wire saw. Among these, a wire saw is preferable from the viewpoint of flattening the cutting surface with high accuracy. A ceramic composite having a desired size or thickness can be obtained by the processing step. The ceramic composite is preferably cut into a plate-like body having a first main surface serving as a light incident surface and a second main surface located on the opposite side of the first main surface and serving as a light emitting surface. The plate thickness of the ceramic composite of the plate-like body is preferably 90 μm or more and 300 μm or less, more preferably 95 μm or more and 250 μm or less, and further preferably 100 μm or more and 200 μm or less. When the ceramic composite is a plate-like body and the plate thickness thereof is cut to a range of 90 μm or more and 300 μm or less, the ceramic composite can be easily processed and has good wavelength conversion efficiency, and the light extraction efficiency can be improved.

Light emitting device

The light-emitting device is provided with a ceramic composite and a light source for emitting light for exciting a rare earth aluminate phosphor contained in the ceramic composite.

The light source is preferably a semiconductor laser. In this way, the excitation light emitted from the semiconductor laser is made incident on the ceramic composite, and the mixed color light of the light wavelength-converted by the rare earth aluminate phosphor contained in the ceramic composite and the light from the light source is separated into red light, green light, and blue light by a plurality of optical systems such as a lens array, a polarization conversion element, and a color separation optical system, and is modulated in accordance with image information, whereby a light-emitting device that forms color image light can be produced. The light emitting device may be used for a projector. The light-emitting device using the semiconductor laser as a light source may be a light-emitting device in which excitation light emitted from the semiconductor laser is incident on the ceramic composite via an optical system such as a dichroic mirror or a collimating optical system.

The light source of the light emitting device may be a light emitting element including an LED chip. The ceramic composite can convert light emitted from the light emitting element by combining with the light emitting element, and thus constitutes a light emitting device that emits mixed light of light emitted from the light emitting element and light wavelength-converted by the rare earth aluminate phosphor contained in the ceramic composite. As the light-emitting element, for example, a light-emitting element that emits light having an emission peak wavelength in a wavelength range of 350nm to 500nm, preferably 440nm to 470nm, can be used. As the light-emitting element, for example, a light-emitting element using a nitride semiconductor (In)_XAl_YGa_1-X-YN, 0. ltoreq. X, 0. ltoreq. Y, X + Y. ltoreq.1). By using a semiconductor light emitting element as an excitation light source, a light emitting device having high efficiency, high linearity of output with respect to input, and high and stable resistance to mechanical impact can be obtained.