Silicate phosphors and light-emitting devices

Abstract

The present invention provides silicate phosphors and light-emitting devices. [Solution] A silicate phosphor having a composition represented by the following formula (1). A light-emitting device comprising the silicate phosphor and a light-emitting element having an emission peak wavelength in the range of 365 nm to 460 nm and irradiating the silicate phosphor. (Ca x Sr 1-x―y Ba y ) 3―z MgSi2O8:Eu z (1) (In equation (1) above, x, y and z are each 0

Description

Technical Field

[0001] The present invention relates to a silicate phosphor and a light-emitting device.

Background Art

[0002] In Patent Document 1, in order to adjust the white color during light emission, a phosphor member including a silicate phosphor that is excited by light having a first peak wavelength within the range of 410 nm or more and 460 nm or less emitted from a light-emitting element and emits light having a second peak wavelength within the range of 461 nm or more and 480 nm or less is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present disclosure is to provide a silicate phosphor and a light-emitting device capable of increasing the minimum value of the emission intensity in the emission spectrum of the light-emitting device in order to obtain a light-emitting device that can emit white light with excellent color reproducibility.

Means for Solving the Problems

[0005] A first aspect is a silicate phosphor having a composition represented by the following formula (1). (Ca x Sr 1-x-y Ba y ) 3-z MgSi2O8:Eu z (1) (In the formula (1), x, y, and z satisfy 0 < x ≤ 0.5, 0 ≤ y ≤ 0.1, and 0 < z ≤ 0.3, respectively.)

[0006] A second aspect is a light-emitting device including the silicate phosphor and a light-emitting element that has an emission peak wavelength within a range of 365 nm or more and 460 nm or less and irradiates the silicate phosphor.

Advantages of the Invention

[0007] According to one aspect of the present disclosure, it is possible to provide a silicate phosphor and a light-emitting device capable of increasing the minimum value of the emission intensity in the emission spectrum of the light-emitting device.

Brief Description of the Drawings

[0008] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a first configuration example of a light-emitting device. [Figure 2] FIG. 2 is a schematic cross-sectional view showing another example of the first configuration example of the light-emitting device. [Figure 3] FIG. 3 is a schematic plan view showing a second configuration example of the light-emitting device. [Figure 4] FIG. 4 is a schematic cross-sectional view showing the second configuration of the light-emitting device. [Figure 5] FIG. 5 is a diagram showing the relative emission energy (%) in the temperature range from 25 °C (room temperature) to 300 °C for the silicate phosphor according to Examples 2 and 4 and the silicate phosphor according to Comparative Example 1. [Figure 6] FIG. 6 is a diagram showing the region FL in the chromaticity diagram of the CIE1931 color system. [Figure 7] FIG. 7 is a diagram showing the emission spectra of the light-emitting device according to Example 1 and the light-emitting device according to Comparative Example 2. [Figure 8] FIG. 8 is a diagram showing the emission spectra of the light-emitting device according to Example 2 and the light-emitting device according to Comparative Example 2. [Figure 9] FIG. 9 is a diagram showing the emission spectra of the light-emitting device according to Example 3 and the light-emitting device according to Comparative Example 2. [Figure 10] FIG. 10 is a diagram showing the emission spectra of the light-emitting device according to Example 4 and the light-emitting device according to Comparative Example 2. [Figure 11] FIG. 11 is a diagram showing the emission spectrum of the light-emitting device according to Example 5 and the emission spectrum of the light-emitting device according to Comparative Example 2. [Figure 12] FIG. 12 is a diagram showing the emission spectrum of the light-emitting device according to Example 6 and the emission spectrum of the light-emitting device according to Comparative Example 2. [Figure 13] FIG. 13 is a diagram showing the emission spectrum of the light-emitting device according to Example 7 and the emission spectrum of the light-emitting device according to Comparative Example 2. [Figure 14] FIG. 14 is a diagram showing the emission spectra of the light-emitting devices according to Comparative Examples 1 and 2.

BEST MODE FOR CARRYING OUT THE INVENTION

[0009] Hereinafter, the silicate phosphor and the light-emitting device according to the present disclosure 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 silicate phosphor and light-emitting device. For visible light, the relationship between the color name and the chromaticity coordinates, the relationship between the wavelength range of light and the color name of monochromatic light, etc. follow JIS Z8110.

[0010] The silicate phosphor has a composition represented by the following formula (1). (Ca x Sr 1-x-y Ba y ) 3-z MgSi2O8:Eu z (1) (In the above formula (1), x, y, and z satisfy 0 < x ≦ 0.5, 0 ≦ y ≦ 0.1, and 0 < z ≦ 0.3, respectively.) In this specification, in the composition formula representing the composition of the phosphor, before the colon (:) represents the elements constituting the host crystal and their molar ratios, and after the colon (:) represents the activating element.

[0011] The silicate phosphor having the composition represented by formula (1) contains Ca and Sr as essential elements, and in the emission spectrum of the silicate phosphor due to excitation light from an excitation light source, it has an emission peak wavelength in a specific wavelength range. This allows the emission spectrum of the light-emitting device containing the light-emitting element and the silicate phosphor having the composition represented by formula (1) to have a high minimum emission intensity, a good spectral balance, and light with excellent color reproducibility to be emitted from the light-emitting device. Furthermore, when the silicate phosphor having the composition represented by formula (1) is included in the light-emitting device, it can diffuse the light from the excitation light source, and the emission color of the light-emitting device can be set to white light with x and y coordinates within a specific range on the chromaticity diagram of the CIE 1931 color system. In this specification, the phosphor containing the silicate phosphor having the composition represented by formula (1) is also referred to as the first phosphor.

[0012] A light-emitting device for a camera flash mounted on a smartphone or other electronic device comprises, for example, a light-emitting element, a second phosphor that emits light having an emission peak wavelength in the wavelength range from yellow to green emission when irradiated with excitation light from the light-emitting element, and a third phosphor that emits light having an emission peak wavelength in the wavelength range of red emission. The light-emitting element has an emission peak wavelength in the range of 365 nm to 460 nm. In a light-emitting device comprising such a light-emitting element, a second phosphor, and a third phosphor, the emission intensity in the wavelength range of blue-green emission tends to be low in the emission spectrum of the light-emitting device, and the emission intensity in the range of 460 nm to 490 nm tends to be the minimum value. In the emission spectrum of the light-emitting device, the wavelength range in which the emission intensity is the minimum value may be in the range of 465 nm to 485 nm, or in the range of 470 nm to 480 nm. In the emission spectrum of a light-emitting device, the smaller the minimum emission intensity in the range of 460 nm or above, or between 460 nm and 490 nm, the more the emission intensity differs across wavelength ranges, disrupting the spectral balance of the emission spectrum and reducing the color reproducibility of the irradiated object. High color reproducibility of the irradiated object from a light-emitting device is desirable; for example, light-emitting devices for camera flashes are sometimes required to emit light with excellent color reproducibility. By including a silicate phosphor having the composition represented by formula (1) above, the light-emitting device can increase the emission intensity in the range of 460 nm to 490 nm where the emission intensity is minimum in the emission spectrum of the light-emitting device, improving the spectral balance of the emission spectrum and emitting light with high color reproducibility of the irradiated object.

[0013] In 1 mole of the composition represented by the formula (1) of the silicate phosphor, the molar ratio of Ca is represented by the product of the variable x and the numerical value obtained by subtracting the variable z from 3 (represented as "3 - z"). In the composition represented by the formula (1), when the variable x exceeds 0 and is 0.5 or less (0 < x ≤ 0.5), by containing Ca, the crystal structure of the silicate phosphor that does not contain Ca changes, and the emission peak wavelength of the emission of the silicate phosphor having the composition represented by the formula (1) by irradiation with excitation light shifts to the longer wavelength side. In the emission spectrum of a light-emitting device including the silicate phosphor having the composition represented by the formula (1), the emission intensity in the wavelength range that becomes the minimum value can be made higher. The silicate phosphor preferably has the variable x in the range of 0.01 or more and 0.45 or less (0.01 ≤ x ≤ 0.45) in the composition represented by the formula (1), more preferably in the range of 0.02 or more and 0.4 or less (0.02 ≤ x ≤ 0.4), still more preferably in the range of 0.03 or more and 0.35 or less (0.03 ≤ x ≤ 0.35), and even more preferably in the range of 0.04 or more and 0.3 or less (0.04 ≤ x ≤ 0.3).

[0014] In 1 mole of the composition represented by the formula (1) of the silicate phosphor, the molar ratio of Eu is represented by the variable z. Eu is an activating element of the silicate phosphor. In the composition of the silicate phosphor represented by the formula (1), the variable z is more than 0 and not more than 0.3 (0 < z ≦ 0.3), preferably within the range of 0.01 or more and 0.295 or less (0.01 ≦ z ≦ 0.295), more preferably within the range of 0.02 or more and 0.29 or less (0.02 ≦ z ≦ 0.29), still more preferably within the range of 0.03 or more and 0.285 or less (0.03 ≦ z ≦ 0.285), and particularly preferably within the range of 0.04 or more and 0.28 or less (0.04 ≦ z ≦ 0.28). When the molar ratio of Eu, which is an activating element, in 1 mole of the composition represented by the formula (1) of the silicate phosphor is more than 0 and not more than 0.3 (0 < z ≦ 0.3), the silicate phosphor having the composition represented by the formula (1) emits light having an emission peak wavelength within the range of 460 nm or more and 490 nm or less in the emission spectrum by irradiation with light from a light-emitting element having an emission peak wavelength within the range of 365 nm or more and 460 nm or less. In the emission spectrum of a light-emitting device using the silicate phosphor, the emission intensity within the range of 460 nm or more and 490 nm or less, where the emission intensity is at a minimum value, can be increased. When the variable z representing the molar ratio of Eu in the composition of the silicate phosphor represented by the formula (1) is 0, no light is emitted even when excited light is irradiated because no activating element is contained. When the variable z representing the molar ratio of Eu in the composition of the silicate phosphor represented by the formula (1) exceeds 0.3, the amount of the activating element in 1 mole of the composition is too large, and the emission intensity may decrease due to concentration quenching.

[0015] In a silicate phosphor composition represented by formula (1) above, the molar ratio of Ba in one mole is expressed as the product of the variable y and the value obtained by subtracting the variable z from 3 (3-z). In a silicate phosphor composition represented by formula (1) above, the variable y in the product of the variable y representing the molar ratio of Ba and the value obtained by subtracting the variable z from 3 (3-z) is in the range of 0 to 0.1 (0≦y≦0.1), may also be in the range of 0 to 0.08 (0≦y≦0.08), may also be in the range of 0 to 0.05 (0≦y≦0.05), or may also be in the range of 0 to 0.03 (0≦y≦0.03). In a silicate phosphor composition represented by formula (1) above, Ba may not be included, and the variable y may be 0 (y=0). Since silicate phosphors contain both Ca and Sr, they may also contain Ba, which is an alkaline earth metal element of the same group.

[0016] A silicate phosphor having the composition represented by formula (1) preferably has an emission peak wavelength in the emission spectrum between 460 nm and 490 nm. More preferably, a silicate phosphor having the composition represented by formula (1) has an emission peak wavelength in the emission spectrum between 462 nm and 485 nm, even more preferably between 463 nm and 482 nm, and particularly preferably between 464 nm and 480 nm. A silicate phosphor having the composition represented by formula (1) emits light with an emission peak wavelength in the emission spectrum between 460 nm and 490 nm when irradiated with excitation light, and can increase the emission intensity in the range of 460 nm to 490 nm, where the emission intensity is minimum, in the emission spectrum of a light-emitting device using a silicate phosphor. The excitation light irradiated onto the silicate phosphor preferably has an emission peak wavelength in the emission spectrum within the range of 365 nm to 460 nm, but may also have an emission peak wavelength in the range of 370 nm to 460 nm, 380 nm to 460 nm, or 390 nm to 460 nm.

[0017] The silicate phosphor having the composition represented by formula (1) preferably emits light in which, in the chromaticity coordinates (x, y) of the CIE1931 color system measured from the emission spectrum of the silicate phosphor when irradiated with excitation light having an emission peak wavelength of 420 nm, x is in the range of 0.125 to 0.135 and y is in the range of 0.100 to 0.200, but may also emit light in which x is in the range of 0.126 to 0.134 and y is in the range of 0.105 to 0.190. A silicate phosphor having the composition represented by formula (1) can emit white light when used in a light-emitting device, provided that the chromaticity coordinates (x, y) in the CIE1931 color system chromaticity diagram, measured from the emission spectrum of the silicate phosphor, are within the range of 0.125 to 0.135 for x and 0.100 to 0.200 for y.

[0018] The silicate phosphor having the composition represented by formula (1) preferably has a full width at half maximum of the emission spectrum having an emission peak wavelength in the range of 36 nm to 50 nm. More preferably, the silicate phosphor having the composition represented by formula (1) has a full width at half maximum of the emission spectrum having an emission peak wavelength in the range of 37 nm to 48 nm, even more preferably in the range of 38 nm to 45 nm, and particularly preferably in the range of 39 nm to 43 nm. If the silicate phosphor having the composition represented by formula (1) has a full width at half maximum of the emission spectrum having an emission peak wavelength in the range of 36 nm to 50 nm, then upon irradiation with excitation light, it can emit light that increases the emission intensity in the range of 460 nm to 490 nm, where the emission intensity is at its minimum, in the emission spectrum of a light-emitting device using the silicate phosphor.

[0019] Preferably, a silicate phosphor having the composition represented by formula (1) has an emission energy value of 85% or more of the emission spectrum of the silicate phosphor at 200°C when irradiated with excitation light having an emission peak wavelength of 420 nm, with the emission energy value of the emission spectrum of the silicate phosphor at 25°C being set to 100%. If the energy value of the emission spectrum of the silicate phosphor at 200°C (relative emission energy at 200°C) is 85% or more when irradiated with excitation light having an emission peak wavelength of 420 nm, with the emission energy value of the emission spectrum of the silicate phosphor at 25°C being set to 100%, then the emission intensity can be maintained even at high temperatures, the temperature characteristics are good, and the silicate phosphor is highly reliable. A silicate phosphor having the composition represented by formula (1) can, when irradiated with excitation light having an emission peak wavelength of 420 nm, have a relative emission energy of 85% or more at 200°C, with the emission intensity at the emission peak wavelength at 25°C set to 100%. This allows for increased emission intensity within the range of 460 nm to 490 nm, where the emission intensity is minimum in the emission spectrum of a light-emitting device using the silicate phosphor, and enables the emission of light with high color reproducibility of the irradiated object. A silicate phosphor having the composition represented by formula (1) can, when irradiated with excitation light having an emission peak wavelength of 420 nm, have an emission energy value of the emission spectrum of the silicate phosphor at 200°C (relative emission energy at 200°C) that is 83% or more, 84% or more, preferably 85% or more, 85.1% or more, 85.5% or more, 100%, or 99% or less. The energy value of the emission spectrum of a silicate phosphor is the integral value of the emission spectrum of the silicate phosphor in the wavelength range of 480 nm to 650 nm when irradiated with excitation light having an emission peak wavelength of 420 nm.The emission energy value of the emission spectrum of a silicate phosphor at 200°C (relative emission energy at 200°C) is the relative value of the integral value of the emission spectrum of the silicate phosphor at 200°C in the range of 480 nm to 650 nm, with the integral value of the emission spectrum of the silicate phosphor at 25°C in the range of 480 nm to 650 nm set to 100% when irradiated with excitation light with an emission peak wavelength of 420 nm.

[0020] The silicate phosphor having the composition represented by formula (1) preferably has a central particle size of 50% of the cumulative volume based on the volume-based particle size distribution measured by laser diffraction particle size distribution analysis, which is in the range of 5.0 μm to 25 μm. If the central particle size of the silicate phosphor having the composition represented by formula (1) is in the range of 5.0 μm to 25 μm, the light emission device using the silicate phosphor can easily diffuse light and emit light with an emission color that satisfies the specified color standard. Furthermore, if the central particle size of the silicate phosphor is in the range of 5.0 μm to 25 μm, the silicate phosphor is easy to handle during the manufacture of the light emission device. Moreover, if the central particle size of the silicate phosphor is in the range of 5.0 μm to 25 μm, it easily absorbs excitation light, and the emission intensity in the range of 460 nm to 490 nm, where the emission intensity is minimum in the emission spectrum of the light emission device, can be increased, and light with high color reproducibility of the irradiated object can be emitted. The silicate phosphor having the composition represented by formula (1) above may have a central particle size within the range of 5.5 μm to 24 μm, or within the range of 5.6 μm to 23 μm. The central particle size refers to the central particle size (median diameter: Dm) at which the cumulative frequency from the smallest diameter side in the volume-based particle size distribution measured by the laser diffraction particle size distribution method reaches 50%. The laser diffraction particle size distribution method is a method that measures particle size without distinguishing between primary and secondary particles by utilizing the scattered light of a laser beam irradiated onto the particles. The laser diffraction particle size distribution method can be measured using commercially available equipment, and can be measured using a laser diffraction particle size distribution analyzer (for example, MASTER SIZER3000, manufactured by MALVERN).

[0021] The silicate phosphor may be a silicate phosphor in which a silicate phosphor having the composition represented by formula (1) is used as a core particle, and aluminum oxide is attached to the surface of this core particle. A method for attaching aluminum oxide to a core particle made of silicate phosphor, using a silicate phosphor having the composition represented by formula (1) as the core particle, may be, for example, by chemical vapor deposition (CVD), to attach aluminum oxide to the surface of the core particle made of silicate phosphor having the composition represented by formula (1), and then heat-treating it in an oxygen-containing atmosphere at a temperature range of, for example, 200°C to 500°C to obtain a silicate phosphor with attached aluminum oxide. A method for attaching aluminum oxide to a core particle made of silicate phosphor having the composition represented by formula (1) as the core particle may be, for example, referred to Japanese Patent Application Publication No. 2021-187960. A silicate phosphor in which aluminum oxide is attached to a core particle made of silicate phosphor having the composition represented by formula (1) can suppress the decrease in luminescence intensity even at high temperatures and can have high durability.

[0022] A method for producing a silicate phosphor includes preparing a raw material mixture containing a Ca source, a Sr source, a Eu source, a Mg source, and a Si source, and optionally containing a Ba source, to obtain a silicate phosphor or silicate phosphor core particles. The method for producing a silicate phosphor may also include depositing aluminum oxide on the surface of the silicate phosphor core particles by CVD and heat-treating them in an oxygen-containing atmosphere at a temperature range of 210°C to 490°C. For example, a method for producing a silicate phosphor can be found in Japanese Patent Application Publication No. 2021-187960.

[0023] The Ca source, Sr source, Eu source, Mg source, Si source, and optionally a Ba source which may be included in the raw material mixture, can be a metal composed of each element or a compound containing each element. Compounds containing the Ca source, Sr source, Eu source, Mg source, Si source, and optionally a Ba source which may be included in the raw material mixture can be oxides, hydroxides, oxynitrides, nitrides, imide compounds, or amide compounds. Specifically, the Ca source, Sr source, Eu source, Mg source, Si source, and optionally a Ba source which may be included in the raw material mixture include CaF2, CaCl2, CaCO3, SrF2, SrCl2, SrCO3, metallic europium, Eu2O3, EuN, imide compounds containing Eu, amide compounds containing Eu, MgF2, MgCl2, MgO, MgCO3, metallic silica, SiO2, Si3N4, Si(NH2)2, and optionally BaF2, BaCl2, BaCO3. The weighed elemental sources are mixed wet or dry using a mixer to obtain a raw material mixture. The mixer can be a pulverizer such as a ball mill, vibratory mill, roll mill, or jet mill, which are commonly used industrially. By pulverizing the raw materials, the specific surface area can be increased. Each elemental source, which is the raw material, may be classified to maintain a specific surface area within a certain range. For the classification of each elemental source, a wet separator such as a sedimentation tank, hydrocyclone, or centrifuge, which are commonly used industrially, may be used, or a dry classifier such as a cyclone or air separator may be used.

[0024] The raw material mixture may contain a flux. Halides can be used as the flux. When a halide is used as the flux, the temperature at which the liquid phase of the halide is formed and the temperature at which the raw material mixture described later is calcined are approximately equal, and the solid-phase reaction between each element source proceeds more uniformly, resulting in silicate phosphor core particles with excellent luminescence properties. Examples of halides used as flux include chlorides or fluorides containing rare earth metal elements such as cerium and europium, and chlorides or fluorides containing alkali metal elements or alkaline earth metal elements. If the elements contained in the flux are elements included in the composition of the silicate phosphor core particles, the molar ratio of the elements contained in the flux may be adjusted to achieve the composition of the silicate phosphor core particles to be obtained, and the flux may be added to the raw material mixture as part of the element source. Even if the elements contained in the flux are elements included in the composition of the silicate phosphor core particles, the flux may be further added to the raw material mixture without considering the composition of the silicate phosphor or silicate phosphor core particles. When the raw material mixture contains flux, in order to further promote the reaction of each element source, the amount of flux added is preferably 10 parts by mass or less per 100 parts by mass of the raw material mixture without flux, but it may also be 5 parts by mass or less, or 1 part by mass or more.

[0025] The raw material mixture can be calcined to obtain silicate phosphor core particles. The raw material mixture can be placed in a crucible or boat made of materials such as silicon carbide (SiC), quartz, alumina, or boron nitride (BN) and calcined in a furnace. The calcination temperature of the raw material mixture is preferably in the range of 1100°C to 1500°C, and more preferably in the range of 1300°C to 1450°C. Calcination may be performed by first calcination followed by second calcination, or by multiple calcinations. The calcination time for each calcination is preferably between 1 hour and 30 hours. Multi-stage calcination, in which the temperature is changed in stages, may also be performed. For example, the first stage of calcination may be performed in the temperature range of 800°C to 1000°C, and then the temperature may be gradually increased to perform the second stage of calcination in the temperature range of 1100°C to 1500°C.

[0026] The firing atmosphere for the raw material mixture is preferably a reducing atmosphere. The firing atmosphere for the raw material mixture may also be a nitrogen atmosphere containing reducing hydrogen gas. The nitrogen gas content in the nitrogen atmosphere containing reducing hydrogen gas is preferably 70% by volume or more, more preferably 80% by volume or more, and even more preferably 90% by volume or more. The hydrogen gas content in the nitrogen atmosphere containing reducing hydrogen gas is preferably 1% by volume or more, more preferably 5% by volume or more, and even more preferably 10% by volume or more. The firing atmosphere for the raw material mixture may also be a reducing atmosphere using solid carbon in an atmospheric atmosphere. By firing the raw material mixture in a highly reducing atmosphere, silicate phosphor core particles with excellent luminescence properties can be obtained. For example, when the raw material mixture is fired in a highly reducing atmosphere, the content of divalent Eu in the fired product increases. Divalent Eu is easily oxidized to trivalent Eu, but by firing the raw material mixture in a highly reducing atmosphere, the trivalent Eu (Eu) contained in the fired product is reduced. 3+ ) is divalent Eu(Eu 2+ It is reduced to ). Therefore, the divalent Eu(Eu) that becomes the luminescence center 2+ A calcined product with an increased content of ) can be obtained, and silicate phosphors or silicate phosphor core particles with excellent luminescence properties can be obtained.

[0027] The pressure of the firing atmosphere may be standard atmospheric pressure (approximately 0.1 MPa), or it may be a pressurized atmosphere with a gauge pressure of 0.1 MPa to 200 MPa. As the heat treatment temperature increases, the crystal structure of the fired material tends to decompose more easily, but by using a pressurized atmosphere, the decomposition of the crystal structure can be suppressed, and the decrease in the luminescence intensity of the resulting silicate phosphor core particles can be suppressed. The pressure of the heat treatment atmosphere is more preferably in the range of 0.1 MPa to 100 MPa, even more preferably in the range of 0.5 MPa to 10 MPa, and even more preferably 1.0 MPa or less from the viewpoint of ease of manufacture.

[0028] A raw material mixture may be calcined, and the resulting calcined product may be post-treated to obtain silicate phosphors or silicate phosphor core particles. Post-treatment may include, for example, grinding, dispersion, solid-liquid separation, and drying. Solid-liquid separation can be performed by industrially commonly used methods such as filtration, suction filtration, pressure filtration, centrifugation, and decantation. Drying can be performed by industrially commonly used equipment such as vacuum dryers, hot air dryers, conical dryers, and rotary evaporators. The calcined product can be post-treated as needed, and the post-treated calcined product can be used as silicate phosphors or silicate phosphor core particles.

[0029] Aluminum oxide can be deposited on the surface of the obtained silicate phosphor core particles by CVD. The step of depositing aluminum oxide and heat-treating it is preferably performed by a fluidized bed CVD method. The aluminum compound used as the raw material for the aluminum oxide is preferably an organoaluminum compound. The organoaluminum compound can be a dialkylaluminum halide such as trialkylaluminum, trialkoxyaluminum, or dimethylaluminum chloride. To improve the durability of the resulting silicate phosphor and to ensure good handling, the organoaluminum compound is preferably trialkylaluminum having three alkyl groups, more preferably trialkylaluminum with 1 to 3 carbon atoms in each alkyl group, and even more preferably trimethylaluminum. In the step of depositing aluminum oxide, it is preferable to use a raw material gas containing trimethylaluminum. When depositing aluminum oxide by a fluidized bed CVD method, it is preferable to vaporize trimethylaluminum, which is the raw material gas, into the fluidizing gas forming the fluidized bed, and to form the fluidized bed using a mixed gas of the raw material gas and the fluidizing gas. The content of the raw material gas in the mixed gas of the raw material gas and the fluidizing gas is preferably in the range of 0.5% by volume or more and 3.5% by volume or less, and may also be in the range of 1.0% by volume or more and 3.0% by volume or less. In the process of depositing aluminum oxide, the fluidizing gas that forms the fluidized bed is preferably nitrogen gas. When the fluidizing gas is nitrogen gas, the nitrogen concentration of the fluidizing gas is preferably 100% by volume, but may be 99% by volume or more, or 98% by volume or more.

[0030] In the process of depositing aluminum oxide, for example, when using a fluidized bed CVD apparatus, silicate phosphor core particles are introduced into the reaction tube where the fluidized bed is formed, and a mixed gas containing a raw material gas obtained by vaporizing an organoaluminum compound and a fluidizing gas is supplied from, for example, the bottom of the reaction tube. It is preferable to supply oxygen to the reaction tube in order to react with the raw material gas obtained by vaporizing an organoaluminum compound. For example, when a mixed gas containing a raw material gas and a fluidizing gas is supplied from the bottom of the reaction tube, oxygen may be supplied from the top of the reaction tube or from the bottom of the reaction tube. It is preferable to supply oxygen from the top of the reaction tube because it is easier to react with the raw material gas in the mixed gas supplied from the bottom of the reaction tube. It is preferable to supply oxygen such that the oxygen concentration in the atmosphere is within the range of 5% by volume or more and 60% by volume or less, but it may also be supplied so that it is within the range of 10% by volume or more and 55% by volume or within the range of 20% by volume or more and 50% by volume or less.

[0031] It is preferable to heat-treat the silicate phosphor core particles in an oxygen-containing atmosphere at a temperature range of 210°C to 490°C while depositing aluminum oxide onto the surface of the silicate phosphor core particles using the CVD method. By heat-treating in this temperature range, it is possible to form a film containing aluminum oxide over the entire surface of the silicate phosphor core particles without damaging the crystal structure of the silicate phosphor core particles, while filling in oxygen vacancies present in the crystal structure with oxygen in the atmosphere, and increasing the reactivity of the raw material, such as trialkylaluminum. As a result, the resulting silicate phosphor has excellent durability, maintaining its luminous flux even under high temperature and high humidity conditions without a decrease in brightness. Furthermore, by heat-treating the silicate phosphor core particles in an oxygen-containing atmosphere while depositing aluminum oxide onto the surface of the silicate phosphor core particles using the CVD method, moisture or hydroxyl groups (OH) attached to the surface of the silicate phosphor core particles are removed, which is presumed to improve the adhesion between the silicate phosphor core particles and the aluminum oxide. The temperature at which heat treatment is performed in an oxygen-containing atmosphere may be in the range of 250°C to 450°C, or in the range of 300°C to 400°C.

[0032] The time for heat treatment in an oxygen-containing atmosphere at a temperature range of 210°C to 490°C while depositing aluminum oxide may be, for example, 1 hour or more, 1 hour to 24 hours, or 2 hours to 20 hours.

[0033] The process of depositing aluminum oxide by CVD and the heat treatment in an oxygen-containing atmosphere at a temperature range of 210°C to 490°C may be carried out as separate processes. When the process of depositing aluminum oxide by CVD and the process of heat treatment in an oxygen-containing atmosphere are carried out as separate processes, the heat treatment in an oxygen-containing atmosphere at a temperature range of 210°C to 490°C should be performed before and / or after the process of depositing aluminum oxide by CVD. The heat treatment may be carried out using a fluidized bed CVD apparatus used when depositing aluminum oxide by CVD. When using a fluidized bed CVD apparatus, it is preferable that oxygen be supplied to the reaction tube containing silicate phosphor core particles before and / or after depositing aluminum oxide so that the oxygen concentration in the reaction tube atmosphere is between 10% by volume and 80% by volume. It is preferable that the oxygen be supplied so that the oxygen concentration in the atmosphere is between 5% by volume and 60% by volume, but it may also be supplied so that it is between 10% by volume and 55% by volume, or between 20% by volume and 50% by volume. Oxygen may be supplied from the top or bottom of the reaction tube. Heat treatment in an oxygen-containing atmosphere may be performed using equipment other than a fluidized bed CVD apparatus.

[0034] The temperature for heat treatment in an oxygen-containing atmosphere is in the range of 210°C to 490°C, preferably in the range of 220°C to 480°C, more preferably in the range of 250°C to 450°C, even more preferably in the range of 280°C to 420°C, and particularly preferably in the range of 300°C to 400°C. If the temperature for heat treatment in an oxygen-containing atmosphere is in the range of 210°C to 490°C, it is possible to remove moisture or hydroxyl groups (OH) attached to the surface of the silicate phosphor core particles while filling oxygen vacancies present in the crystal structure of the silicate phosphor core particles with oxygen in the atmosphere, without damaging the crystal structure of the silicate phosphor core particles by heat treatment, thereby obtaining a silicate phosphor with improved adhesion between the silicate phosphor core particles and aluminum oxide.

[0035] The heat treatment time in an oxygen-containing atmosphere at a temperature range of 210°C to 490°C is preferably 1 hour to 24 hours, more preferably 2 hours to 20 hours, and even more preferably 3 hours to 18 hours. If the total heat treatment time in an oxygen-containing atmosphere at a temperature range of 210°C to 490°C is 1 hour to 24 hours, it is possible to obtain a silicate phosphor with excellent durability that can maintain luminous flux even under high temperature and high humidity conditions, by filling oxygen vacancies present in the crystal structure of the silicate phosphor core particles with oxygen in the atmosphere without damaging the crystal structure of the silicate phosphor core particles, thereby increasing the adhesion between the silicate phosphor core particles and aluminum oxide, suppressing the initial decrease in brightness, and filling oxygen vacancies present in the crystal structure of the silicate phosphor core particles with oxygen in the atmosphere.

[0036] The light-emitting device comprises a silicate phosphor having a composition represented by formula (1) and a light-emitting element having an emission peak wavelength in the range of 365 nm to 460 nm and irradiating the silicate phosphor with excitation light.

[0037] The silicate phosphor included in the light-emitting device may be included in the wavelength conversion member together with phosphors having a composition and emission peak wavelength different from the silicate phosphor having the composition represented by formula (1). The silicate phosphor included in the light-emitting device may be included in a layer different from the phosphor layer, for example, a diffusion layer, which contains phosphors having a composition and emission peak wavelength different from the silicate phosphor having the composition represented by formula (1). When the light-emitting device comprises a phosphor layer containing phosphors having a composition and emission peak wavelength different from the silicate phosphor having the composition represented by formula (1), and a diffusion layer containing silicate phosphor having the composition represented by formula (1), it is preferable that the diffusion layer be provided on the light-emitting side that emits light from the light-emitting device to the outside. When a light-emitting device includes a phosphor with a composition and emission peak wavelength different from the silicate phosphor having the composition represented by formula (1) and a silicate phosphor having the composition represented by formula (1) in the same wavelength conversion member, the phosphor with a composition and emission peak wavelength different from the aforementioned silicate phosphor and the silicate phosphor may be arranged to be mixed together, the phosphor with a composition and emission peak wavelength different from the aforementioned silicate phosphor may be arranged to be mostly contained on the light-emitting side, or the silicate phosphor may be arranged to be mostly contained on the light-emitting side. When a silicate phosphor having the composition represented by formula (1) is included in the light-emitting device, it is easier to make the appearance color of the top surface of the light-emitting device white when it is not emitting light, and the appearance color of the top surface can be made less conspicuous than that of a typical light-emitting device whose appearance color of the top surface is yellow when it is not emitting light.

[0038] When the light-emitting device includes a silicate phosphor having the composition represented by formula (1) and a phosphor with a different composition and emission peak wavelength from the silicate phosphor, it is preferable that the silicate phosphor content is in the range of 45% to 55% by mass relative to 100% by mass of the total amount of phosphors contained in the light-emitting device. When the silicate phosphor content is in the range of 45% to 55% by mass relative to 100% by mass of the total amount of phosphors contained in the light-emitting device, the emission intensity in the minimum value range of 460 nm to 490 nm in the emission spectrum of the light-emitting device can be made higher, and light with excellent color reproducibility can be emitted from the light-emitting device. Furthermore, when the silicate phosphor content having the composition represented by formula (1) is in the range of 45% to 55% by mass relative to 100% by mass of the total amount of phosphors contained in the light-emitting device, the appearance color of the top surface of the light-emitting device when not emitting light can be made white, making the appearance color of the top surface less conspicuous than that of a typical light-emitting device where the appearance color of the top surface is yellow when not emitting light. If the content of silicate phosphor having the composition represented by formula (1) is in the range of 45% to 55% by mass relative to 100% by mass of the total amount of phosphors contained in the light-emitting device, then even if the light-emitting device does not contain white pigments or fillers (e.g., titanium dioxide) to make the appearance color of the top surface of the light-emitting device white when not emitting light, the appearance color of the top surface of the light-emitting device when not emitting light can be made less conspicuous than that of a typical light-emitting device whose top surface is yellow when not emitting light. Preferably, when the light-emitting device is emitting light, the color tone of the top surface of the light-emitting device is such that, for example, the correlated color temperature measured in accordance with JIS Z8725 is between 3000K and 7000K, and the deviation of the blackbody radiation trajectory (duv) is in the range of -0.02 to +0.02. More preferably, the content of silicate phosphor relative to 100% by mass of the total amount of phosphors contained in the light-emitting device is in the range of 46% to 54% by mass, more preferably in the range of 47% to 53% by mass, and may also be in the range of 48% to 52% by mass.

[0039] A semiconductor device can be used as a light-emitting element that irradiates a silicate phosphor with excitation light. For example, a nitride semiconductor can be selected as the material for a light-emitting element that emits excitation light having an emission peak wavelength in the range of 365 nm to 460 nm. As the material for the semiconductor structure constituting the light-emitting element, In X Al Y Ga 1-X-Y A range such as N(0≦X≦1, 0≦Y≦1, X+Y≦1) can be used. For the light-emitting element, it is preferable to use, for example, an LED chip or an LD chip.

[0040] The light-emitting element has an emission peak wavelength in the range of 365 nm to 460 nm, may have an emission peak wavelength in the range of 370 nm to 460 nm, may have an emission peak wavelength in the range of 380 nm to 460 nm, or may have an emission peak wavelength in the range of 390 nm to 460 nm. By using the light-emitting element as an excitation light source for a phosphor containing a silicate phosphor having the composition represented by formula (1), it is possible to configure a light-emitting device that emits mixed light in a desired wavelength range from light from the light-emitting element and fluorescence from the phosphor containing the silicate phosphor. The full width at half maximum of the emission peak in the emission spectrum of the light-emitting element can be, for example, 30 nm or less. It is preferable to use a light-emitting element using a nitride semiconductor as the light-emitting element. By using a light-emitting element using a nitride semiconductor as an excitation light source, it is possible to obtain a stable light-emitting device that is highly efficient, has high output linearity with respect to input, and is resistant to mechanical shock.

[0041] Preferably, the light-emitting device emits light within a region enclosed by a first point in the chromaticity coordinates of the CIE1931 color system where x is 0.353 and y is 0.340, a second point where x is 0.338 and y is 0.353, a third point where x is 0.362 and y is 0.382, a fourth point where x is 0.378 and y is 0.369, a first line connecting the first and second points, a second line connecting the second and third points, a third line connecting the third and fourth points, and a fourth straight line connecting the fourth and first points, and preferably emits light where the minimum luminescence intensity in the range of 470 nm to 490 nm in the emission spectrum of the light-emitting device is 25% or more, when the luminescence intensity of the emission peak wavelength of the light-emitting device in the range of 365 nm to 460 nm or more is set to 100%.

[0042] When a light-emitting device emits light within the region (hereinafter also referred to as "region FL") enclosed by the chromaticity coordinates of a first point where x is 0.353 and y is 0.340, a second point where x is 0.338 and y is 0.353, a third point where x is 0.362 and y is 0.382, a fourth point where x is 0.378 and y is 0.369, a first line connecting the first and second points, a second line connecting the second and third points, a third line connecting the third and fourth points, and a fourth line connecting the fourth point and the first point, it can emit white light suitable for use as a camera flash, for example. In the chromaticity coordinates of the CIE1931 color system's chromaticity diagram, the region FL enclosed by the first, second, third, and fourth points, the first line, the second line, the third line, and the fourth line can be seen in Figure 6, which will be described later. The light-emitting device preferably emits light within region FL, and when the emission intensity of the emission peak wavelength of the light-emitting element in the range of 365 nm to 460 nm is set to 100%, the minimum emission intensity in the range of 470 nm to 490 nm in the emission spectrum of the light-emitting device is 25% or more. If the light-emitting device has a minimum emission intensity in the range of 470 nm to 490 nm in its emission spectrum, when the emission intensity of the emission peak wavelength of the light-emitting element in the range of 365 nm to 460 nm is set to 100%, the emission intensity in the range of 460 nm to 490 nm, where the emission intensity is the minimum value in the emission spectrum of the light-emitting device, can be increased, improving the spectral balance of the emission spectrum and enabling the emission of light with high color reproducibility of the irradiated object. The light-emitting device emits light within the region FL, and when the emission intensity of the emission peak wavelength of the light-emitting element in the range of 365 nm to 460 nm is set to 100%, the minimum emission intensity in the range of 470 nm to 490 nm in the emission spectrum of the light-emitting device is more preferably 26% or more, even more preferably 27% or more, and even more preferably 28% or more. The light-emitting device emits light within the region FL, and when the emission intensity of the emission peak wavelength of the light-emitting element in the range of 365 nm to 460 nm is set to 100%, the minimum emission intensity in the range of 470 nm to 490 nm in the emission spectrum of the light-emitting device may be 35% or less, 32% or less, or 30% or less.

[0043] The light-emitting device preferably includes an aluminate phosphor having the composition represented by the following formula (2) and a nitride phosphor represented by the following formula (3). (Lu,Y,Gd,Tb)3(Al,Ga)5O 12 :Ce (2) (Sr,Ca)AlSiN3:Eu (3) In this specification, multiple elements separated by commas (,) in a composition formula mean that the composition contains at least one of these multiple elements.

[0044] The light-emitting device, by including an aluminate phosphor having the composition represented by formula (2) and a nitride phosphor represented by formula (3), can emit white light suitable for use as a light-emitting device for a camera flash, for example. Furthermore, by including an aluminate phosphor having the composition represented by formula (2) and a nitride phosphor represented by formula (3), the light-emitting device can emit light in the FL region, for example, on the chromaticity diagram of the CIE 1931 color system, and can be suitably used as a light-emitting device for a camera flash. The aluminate phosphor having the composition represented by formula (2) and the nitride phosphor represented by formula (3) included in the light-emitting device may be included in the same wavelength conversion member as the silicate phosphor having the composition represented by formula (1), or may be included together with the silicate phosphor in the same phosphor layer constituting the wavelength conversion member. If the wavelength conversion member is composed of multiple layers, the aluminate phosphor having the composition represented by formula (2) and the nitride phosphor represented by formula (3) included in the light-emitting device may be included in a phosphor layer that is a layer separate from the diffusion layer containing the silicate phosphor.

[0045] When the light-emitting device includes a silicate phosphor having the composition represented by formula (1), an aluminate phosphor having the composition represented by formula (2), and a nitride phosphor represented by formula (3), it is preferable that the total content of the aluminate phosphor having the composition represented by formula (2) and the nitride phosphor represented by formula (3) is within the range of 45% by mass or more and 55% by mass or less, relative to 100% by mass of the total amount of phosphors contained in the light-emitting device. When the total content of the aluminate phosphor having the composition represented by formula (2) and the nitride phosphor represented by formula (3) is within the range of 45% by mass or more and 55% by mass or less, relative to 100% by mass of the total amount of phosphors contained in the light-emitting device, the light from the excitation light source can be diffused when the silicate phosphor having the composition represented by formula (1) is included in the light-emitting device, and the emission color of the light-emitting device can be made white, with the x and y coordinates of the chromaticity diagram of the CIE1931 color system within a specific range. It is more preferable that the total content of the aluminate phosphor having the composition represented by formula (2) and the nitride phosphor represented by formula (3) is in the range of 46% by mass or more and 54% by mass or less, more preferably in the range of 47% by mass or more and 53% by mass or less, and may also be in the range of 48% by mass or more and 52% by mass or less, based on 100% by mass of the total amount of phosphors contained in the light-emitting device.

[0046] When the light-emitting device includes a silicate phosphor having the composition represented by formula (1), an aluminate phosphor having the composition represented by formula (2), and a nitride phosphor represented by formula (3), the content of the nitride phosphor having the composition represented by formula (3) relative to 100% by mass of the total amount of phosphors contained in the light-emitting device should be such that the light-emitting device emits white light in the chromaticity diagram of the CIE 1931 color system, preferably in the aforementioned region FL. When the light-emitting device includes a silicate phosphor having the composition represented by formula (1), an aluminate phosphor having the composition represented by formula (2), and a nitride phosphor represented by formula (3), the content of the nitride phosphor having the composition represented by formula (3) relative to 100% by mass of the total amount of phosphors contained in the light-emitting device may be in the range of 1.0% by mass or more and 5.5% by mass or less, or in the range of 2.0% by mass or more and 5.0% by mass or less.

[0047] An example of a light-emitting device will be described based on the drawings. Figure 1 is a schematic cross-sectional view showing an example of a first configuration of the light-emitting device. Figure 2 is a schematic cross-sectional view showing another example of the first configuration of the light-emitting device.

[0048] As shown in Figure 1, the light-emitting device 100 comprises a molded body 40 having a recess, a light-emitting element 10 which serves as an excitation light source, and a wavelength conversion member 50 which covers the light-emitting element 10. The molded body 40 is integrally molded from a first lead 20 and a second lead 30 and a resin part 42 containing a thermoplastic resin or a thermosetting resin. At least the first lead 20 and the second lead 30 of the molded body 40 constitute the bottom surface of the recess, and at least the resin part 42 constitutes the side surface of the recess. The light-emitting element 10 is placed on the bottom surface of the recess of the molded body 40. The light-emitting element 10 has a pair of positive and negative electrodes, and these pairs of positive and negative electrodes are electrically connected to the first lead 20 and the second lead 30, respectively, via wires 60. The light-emitting element 10 is covered by the wavelength conversion member 50. Preferably, the wavelength conversion member 50 contains a phosphor 70 that converts the wavelength of light emitted from the light-emitting element 10 and a light-transmitting material. The phosphor 70 essentially includes a first phosphor 71 containing a silicate phosphor. The silicate phosphor contained in the first phosphor 71 contains a silicate phosphor having the composition represented by formula (1). The phosphor 70 may also contain phosphors with different compositions from the first phosphor 71. As shown in Figure 2, it is preferable that the phosphor 70 includes a second phosphor 72 and a third phosphor 73, each having a different composition and emission peak wavelength from the first phosphor. The second phosphor preferably contains an aluminate phosphor having the composition represented by formula (2). The third phosphor preferably contains a nitride phosphor having the composition represented by formula (3). The wavelength conversion member 50 also functions as a member for protecting the light-emitting element 10, wire 60, and phosphor 70, etc., from the external environment. The light-emitting device 100 emits light by receiving power from an external source via the first lead 20 and the second lead 30.

[0049] The first phosphor 71, the second phosphor 72, and the third phosphor 73 may be arranged to be mixed together in the same wavelength conversion member 50, as shown in Figure 1.

[0050] As shown in Figure 2, the first phosphor 71, the second phosphor 72, and the third phosphor 73 may be arranged in the same wavelength conversion member 50 such that the second phosphor 72 and the third phosphor 73 are mixed on the light-emitting side 10, or the first phosphor 71 may be arranged on the light-emitting side 50a of the wavelength conversion member 50. The wavelength conversion member 50 may include a first layer 51 on the light-emitting side 10 where the second phosphor 72 and the third phosphor 73 are mixed, and a second layer 52 adjacent to the first layer 51, which contains more of the first phosphor 71 on the light-emitting side 50a than the first layer 51. The boundary between the first layer 51 and the second layer 52 does not need to be planar. The boundary between the first layer 51 and the second layer 52 may contain a mixture of the first phosphor 71, the second phosphor 72, and the third phosphor 73.

[0051] Figures 3 and 4 show a second configuration example of the light-emitting device. Figure 3 is a schematic plan view of the light-emitting device 200. Figure 4 is a schematic cross-sectional view of the light-emitting device 200 shown in Figure 3, taken along line III-III'. The light-emitting device 200 comprises a light-emitting element 10 having an emission peak wavelength in the range of 365 nm to 460 nm, and a wavelength conversion member 55. The wavelength conversion member 55 includes a wavelength conversion layer 53 containing a phosphor that is excited and emits light by light from the light-emitting element 10, and a diffusion layer 54 disposed on the light-emitting surface side of the wavelength conversion layer 53. The light-emitting element 10 is flip-chip mounted on a substrate 12 via a bump which is a conductive member 61. The wavelength conversion layer 53 of the wavelength conversion member 55 may be a plate-like body having sides between a pair of planes. The wavelength conversion layer 53 of the wavelength conversion member 55 is disposed on the light-emitting surface of the light-emitting element 10 via an adhesive layer 80. The light-emitting element 10 and the wavelength conversion member 55 are covered by a covering member 90 whose sides reflect light. The wavelength conversion layer 53 contains a phosphor that is excited by light from the light-emitting element 10. The wavelength conversion layer 53 of the wavelength conversion member 55 is located on the side of the light-emitting element 10. Preferably, the phosphor included in the wavelength conversion layer 53 includes a second phosphor 72 containing an aluminate phosphor having the composition represented by formula (2) and a third phosphor containing a nitride phosphor having the composition represented by formula (3). The phosphor included in the wavelength conversion layer 53 may also include other phosphors with different compositions and emission peak wavelengths from the second phosphor 72 and the third phosphor 73. The diffusion layer 54 may be a plate-like body having sides between a pair of planes. The diffusion layer 54 of the wavelength conversion member 55 is located on the light-emitting side. Preferably, the diffusion layer of the wavelength conversion member 55 contains a first phosphor 71 containing a silicate phosphor having the composition represented by formula (1). The diffusion layer 54 of the wavelength conversion member 55 may contain a light-diffusing agent such as titanium dioxide. The light-emitting element 10 can receive power from outside the light-emitting device 200 via wiring and conductive members 61 formed on the substrate 12, causing the light-emitting device 200 to emit light. The light-emitting device 200 may include semiconductor elements 11, such as protective elements, to protect the light-emitting element 10 from damage caused by the application of excessive voltage. The semiconductor elements 11 may be mounted on the substrate 12 via the conductive members 61. The covering member 90 is arranged, for example, to cover the semiconductor elements 11.The following describes each component used in the light-emitting device. For further details, please refer to, for example, the disclosure in Japanese Patent Publication No. 2014-112635.

[0052] The light-transmitting material that constitutes the wavelength conversion layer together with the phosphor may be at least one selected from the group consisting of resins, glass, and inorganic materials. The resin may be at least one selected from the group consisting of silicone resins, epoxy resins, phenolic resins, polycarbonate resins, acrylic resins, and modified resins thereof. Silicone resins and modified silicone resins are preferred because they have excellent heat resistance and light resistance. In addition to the phosphor and light-transmitting material, the wavelength conversion member may optionally contain fillers, colorants, and light-diffusing materials. Examples of fillers include silicon dioxide, barium titanate, titanium dioxide, and aluminum oxide.

[0053] The diffusion layer can be a plate-like body made of a translucent material such as glass or resin. Examples of glass include borosilicate glass and quartz glass. Examples of resin include silicone resin and epoxy resin. In addition to the first phosphor, the diffusion layer may also contain fillers and light diffusing materials. Examples of fillers include silicon dioxide, barium titanate, titanium dioxide, and aluminum oxide.

[0054] If the light-emitting device includes a substrate, the substrate is preferably made of an insulating material that does not easily transmit light from the light-emitting element or ambient light. Examples of substrate materials include ceramics such as aluminum oxide and aluminum nitride, and resins such as phenolic resin, epoxy resin, polyimide resin, bismaleimidotriazine resin (BT resin), and polyphthalamide (PPA) resin. If an adhesive layer is interposed between the light-emitting element and the wavelength conversion member, the adhesive constituting the adhesive layer is preferably made of a material that can optically connect the light-emitting element and the wavelength conversion member. The material constituting the adhesive layer is preferably at least one resin selected from the group consisting of epoxy resin, silicone resin, phenolic resin, and polyimide resin. The light-transmitting element does not necessarily have to be placed on the wavelength conversion member.

[0055] Semiconductor elements that may be provided in the light-emitting device as needed include, for example, transistors for controlling light-emitting elements and protective elements for suppressing damage or performance degradation of light-emitting elements due to excessive voltage application. Zener diodes are an example of protective elements. If the light-emitting device is equipped with a covering member, it is preferable to use an insulating material for the covering member. More specifically, examples include phenolic resin, epoxy resin, bismaleimidotriazine resin (BT resin), polyphthalamide (PPA) resin, and silicone resin. Colorants, phosphors, and fillers may be added to the covering member as needed. The light-emitting device may also use bumps as conductive members. As materials for the bumps, Au or its alloys, and as other conductive members, eutectic solder (Au-Sn), Pb-Sn, lead-free solder, etc., can be used.

[0056] An example of a method for manufacturing the light-emitting device of the first configuration example is described below. For further details, see, for example, the disclosure in Japanese Patent Application Publication No. 2010-062272. The method for manufacturing the light-emitting device preferably includes a molded body preparation step, a light-emitting element arrangement step, a wavelength conversion member composition arrangement step, and a resin package formation step. If an aggregate molded body having a plurality of recesses is used as the molded body, a fragmentation step of separating each unit region into resin packages may be included after the resin package formation step.

[0057] In the preparation process for the molded body, multiple leads are integrally molded using a thermosetting resin or thermoplastic resin to prepare a molded body having recesses with side and bottom surfaces. The molded body may be a molded body consisting of an aggregate substrate containing multiple recesses.

[0058] In the process of arranging the light-emitting element, the light-emitting element is placed on the bottom surface of the recess in the molded body, and the positive and negative electrodes of the light-emitting element are connected to the first lead and the second lead by wires.

[0059] In the process of arranging the wavelength conversion member composition, the wavelength conversion member composition is placed in the recess of the molded body. The wavelength conversion member composition may be a composition containing a mixture of a first phosphor, a second phosphor, and a third phosphor. The wavelength conversion member composition may be prepared by placing the first wavelength conversion member composition containing the second and third phosphors in the recess of the molded body and pre-curing it, and then placing the second wavelength conversion member composition containing the first phosphor on the light-emitting side of the pre-cured first wavelength conversion member composition, thereby curing both the first and second wavelength conversion member compositions.

[0060] In the resin package molding process, the wavelength conversion component composition placed in the recesses of the molded body is cured to form a resin package, and a light-emitting device is manufactured. If a molded body consisting of an aggregate substrate containing multiple recesses is used, after the resin package formation process, in the individualization process, each unit region of the aggregate substrate having multiple recesses is separated into resin packages, and individual light-emitting devices are manufactured. In this way, the light-emitting device shown in Figure 1 or Figure 2 can be manufactured.

[0061] An example of a method for manufacturing the light-emitting device of the second configuration example will be described. For further details, please refer to, for example, the disclosures in Japanese Patent Publication No. 2014-112635 or Japanese Patent Publication No. 2017-117912. The method for manufacturing the light-emitting device preferably includes a step of arranging light-emitting elements, a step of arranging semiconductor elements as needed, a step of forming a wavelength conversion member including a wavelength conversion layer, a step of bonding the light-emitting elements and the wavelength conversion member, and a step of forming a coating member.

[0062] For example, in the process of arranging the light-emitting element, the light-emitting element is arranged on a substrate. The light-emitting element and the semiconductor element are mounted on the substrate, for example, using a flip-chip mounting method. Next, in the process of forming a wavelength conversion member including a wavelength conversion layer, the wavelength conversion layer may be obtained by forming a plate-shaped, sheet-shaped, or layered wavelength conversion layer on one surface of a light-transmitting material by printing, bonding, compression molding, or electrodeposition. For example, in the printing method, a wavelength conversion layer composition containing a phosphor and a resin that acts as a binder or solvent can be printed on one surface of a light-transmitting material to form a wavelength conversion member including a wavelength conversion layer. Next, in the bonding process of the light-emitting element and the wavelength conversion member, the wavelength conversion member is placed facing the light-emitting surface of the light-emitting element and bonded to the light-emitting element by an adhesive layer. Next, in the process of forming a coating member, the sides of the light-emitting element and the wavelength conversion member are covered with a coating member composition. This coating member is for reflecting the light emitted from the light-emitting element, and if the light-emitting device also includes a semiconductor element, it is preferable to form the coating member so that the semiconductor element is embedded in the coating member. In this way, the light-emitting devices shown in Figures 3 and 4 can be manufactured. [Examples]

[0063] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0064] Example 1 The following elemental sources were used as raw materials: CaCO3, SrCO3, Eu2O3, MgO, and SiO2. These elemental sources were weighed to create a starting composition with a molar ratio of Si of 2, and the molar ratios of Ca, Sr, Eu, and Mg being Ca:Sr:Eu:Mg = 0.287:2.583:0.13:1.0. SrCl2 was added as a flux at a ratio of 2.0 parts by mass to 100 parts by mass of the total of each compound without flux. Each elemental source was dry-mixed on a dispersion roller using alumina balls (5 mm in diameter) as a media in a 5 L polyethylene container to obtain a raw material mixture. This raw material mixture was packed into an alumina crucible and calcined at 1200°C for 4 hours in a nitrogen atmosphere containing 10 volume% hydrogen gas, which is a reducing atmosphere. 500g of the obtained calcined material, 150g of alumina beads (2mm in diameter) as a medium, and 1000g of deionized water were placed in a 2L polyethylene container and wet-dispersed on a dispersion roller for 1 hour. The resulting first slurry was passed through a mesh with an opening size of 7μm to remove coarse particles. The first slurry was then stirred with deionized water and allowed to stand for 10 minutes. The supernatant was separated to remove fine particles contained in the supernatant. After removing the supernatant, the second slurry was subjected to solid-liquid separation, dried, and passed through a mesh with an opening size of 80μm to obtain silicate phosphor core particles. 300 g of silicate phosphor core particles were placed in the reaction tube of a fluidized CVD apparatus for powders. Trimethylaluminum (TMA) was bubbled into nitrogen (N2) gas (100 vol%), which is the fluidizing gas, to create a mixed gas containing the raw material gas and the fluidizing gas, which was supplied from the bottom of the reaction tube. Oxygen (O2) was supplied to the reaction tube from the top at a flow rate that resulted in an oxygen concentration of 45 vol% in the atmosphere inside the reaction tube. The atmosphere temperature inside the reaction tube was maintained at 300°C, and heat treatment was performed in an oxygen-containing atmosphere for 6.5 hours by CVD, depositing aluminum oxide onto the surface of the silicate phosphor core particles. A film containing aluminum oxide was formed over the entire surface of the silicate phosphor core particles, yielding the silicate phosphor according to Example 1. The silicate phosphor core particles of the silicate phosphor according to Example 1 have a composition represented by formula (1), where the variable x in formula (1) is 0.10 (x=0.10), y is 0 (y=0), and z is 0.13 (z=0.13).

[0065] Example 2 The silicate phosphor according to Example 2 was obtained in the same manner as in Example 1, except that the second slurry, after removing the supernatant liquid, was subjected to solid-liquid separation, dried, and passed through a mesh with an opening size of 10 μm to obtain silicate phosphor core particles. The silicate phosphor core particles of the silicate phosphor according to Example 2 have a composition represented by formula (1), where the variable x in formula (1) is 0.10 (x=0.10), y is 0 (y=0), and z is 0.13 (z=0.13).

[0066] Example 3 The silicate phosphor according to Example 3 was obtained in the same manner as in Example 1, except that the raw material mixture was calcined at 1250°C, the second slurry after removing the supernatant liquid was subjected to solid-liquid separation, dried, and passed through a mesh with an opening size of 15 μm to obtain silicate phosphor core particles. The silicate phosphor core particles of the silicate phosphor according to Example 3 have a composition represented by formula (1), where the variable x in formula (1) is 0.10 (x=0.10), y is 0 (y=0), and z is 0.13 (z=0.13).

[0067] Example 4 The silicate phosphor according to Example 4 was obtained in the same manner as in Example 1, except that the raw material mixture was calcined at 1300°C, the second slurry after removing the supernatant liquid was subjected to solid-liquid separation, dried, and passed through a mesh with an opening size of 20 μm to obtain silicate phosphor core particles. The silicate phosphor core particles of the silicate phosphor according to Example 4 have a composition represented by formula (1), where the variable x in formula (1) is 0.10 (x=0.10), y is 0 (y=0), and z is 0.13 (z=0.13).

[0068] Example 5 The elemental sources CaCO3, SrCO3, Eu2O3, MgO, and SiO2 were used as raw materials. These elemental sources were weighed to create a starting composition with a molar ratio of Si of 2, resulting in Ca:Sr:Eu:Mg = 0.285:2.565:0.15:1.0. The raw material mixture was calcined at 1400°C, and after removing the supernatant liquid, the second slurry was subjected to solid-liquid separation, dried, and passed through a mesh with an opening size of 32 μm to obtain silicate phosphor core particles. The silicate phosphor according to Example 5 was obtained in the same manner as in Example 1. The silicate phosphor core particles of the silicate phosphor according to Example 5 have a composition represented by formula (1), where the variable x in formula (1) is 0.10 (x=0.10), y is 0 (y=0), and z is 0.15 (z=0.15).

[0069] Example 6 The elemental sources CaCO3, SrCO3, Eu2O3, MgO, and SiO2 were used as raw materials. These elemental sources were weighed to form a starting composition with a molar ratio of Si of 2, resulting in Ca:Sr:Eu:Mg = 0.57:2.28:0.15:1.0 to obtain silicate phosphor core particles. The silicate phosphor according to Example 6 was obtained in the same manner as in Example 5. The silicate phosphor core particles of the silicate phosphor according to Example 6 have a composition represented by formula (1), where the variable x in formula (1) is 0.20 (x=0.20), y is 0 (y=0), and z is 0.15 (z=0.15).

[0070] Example 7 The elemental sources CaCO3, SrCO3, Eu2O3, MgO, and SiO2 were used as raw materials. These elemental sources were weighed to obtain silicate phosphor core particles in the same manner as in Example 5, except that the molar ratio of Si was set to 2 and Ca:Sr:Eu:Mg = 1.425:1.425:0.15:1.0. The silicate phosphor core particles of the silicate phosphor according to Example 7 have a composition represented by formula (1), where the variable x in formula (1) is 0.50 (x=0.50), y is 0 (y=0), and z is 0.15 (z=0.15).

[0071] Comparative Example 1 As raw materials, SrCO3, Eu2O3, MgO, and SiO2 elemental sources were used, without a Ca source. These elemental sources were used as the starting composition, and the silicate phosphor core particles were obtained by weighing them so that the molar ratio of Si was 2 and Sr:Eu:Mg = 2.85:0.15:1.0, in the same manner as in Example 5. The silicate phosphor core particles of the silicate phosphor in Comparative Example 1 do not have the composition represented by formula (1), and in the composition represented by formula (1), x is 0 (x=0), y is 0 (y=0), and z is 0.15 (z=0.15). The silicate phosphor in Comparative Example 1 is Sr 2.85 MgSi2O8:Eu 0.15 It has the composition represented by [formula].

[0072] The following evaluations were performed on each silicate phosphor in the examples and comparative examples. The results, along with the calcination temperatures of each raw material mixture in the examples and comparative examples, are shown in Table 1. In Table 1, the symbol "-" indicates that there is no corresponding item or value.

[0073] Hollow particle size (Dm) For each silicate phosphor in the examples and comparative examples, the median diameter (Dm) of the central particle size at which the cumulative frequency from the smaller diameter side in the volume-based particle size distribution is 50% is measured using a laser diffraction particle size distribution analyzer (MASTER SIZER3000, manufactured by MALVERN).

[0074] Emission peak wavelength and full width at half maximum of silicate phosphors For each silicate phosphor in the examples and comparative examples, excitation light with an emission peak wavelength of 420 nm was irradiated onto each silicate phosphor using a quantum efficiency measurement system (QE-2100, manufactured by Otsuka Electronics Co., Ltd.), and the emission spectrum at room temperature (approximately 25°C, 20°C to 30°C) was measured. The emission peak wavelength (λp), full width at half maximum (FWHM), and chromaticity coordinates (x, y) in the CIE1931 colorimetric system were determined from the emission spectrum.

[0075] Reliability evaluation based on temperature characteristics For each silicate phosphor in the examples and comparative examples, excitation light with an emission peak wavelength of 420 nm was irradiated onto each silicate phosphor in a temperature range of 25°C (room temperature) to 300°C, and the emission spectrum at each temperature was measured using a spectrofluorometer (F-4500, Hitachi High-Tech Corporation). Specifically, the emission spectrum of the light-emitting device at each temperature was measured after the surface temperature of the light-emitting device had stabilized at a constant temperature and was left to stand for 5 minutes. The relative energy value of the emission spectrum of each silicate phosphor at each temperature (relative emission energy (%)) was determined, with the energy value of the emission spectrum measured at 25°C set to 100%. The energy value of the emission spectrum of the silicate phosphor determined at each temperature is the integral value of the emission spectrum of the silicate phosphor determined at each temperature in the wavelength range of 480 nm to 650 nm when irradiated with excitation light with an emission peak wavelength of 420 nm. The energy value (relative luminescence energy) of the emission spectrum of the silicate phosphor at each temperature is defined as the relative value of the integral value of the emission spectrum of the silicate phosphor at each temperature in the range of 480 nm to 650 nm, with the integral value of the emission spectrum of the silicate phosphor at 25°C in the range of 480 nm to 650 nm set to 100% when irradiated with excitation light with an emission peak wavelength of 420 nm. The relative luminescence energy (%) at 200°C for each silicate phosphor is listed in Table 1. Figure 5 shows the relative luminescence energy (%) at each temperature in the temperature range from 25°C (room temperature) to 300°C for the silicate phosphors of Examples 2 and 4, and the silicate phosphor of Comparative Example 1. For the silicate phosphors of Examples 5 to 7, the central particle size Dm is relatively large, making it difficult to pack them into the measurement cell, and thus difficult to determine the relative luminescence energy value at 200°C. Therefore, measurement was not possible, and numerical values ​​could not be obtained, and are indicated as "-" in Table 1.

[0076] [Table 1]

[0077] The silicate phosphors according to Examples 1 to 7 have a composition represented by formula (1) and contain Ca and Sr as essential elements. When the silicate phosphors according to Examples 1 to 7 are irradiated with excitation light having an emission peak wavelength in the range of 365 nm to 460 nm, the emission spectrum of the silicate phosphors according to Examples 1 to 7 has an emission peak wavelength in the range of 460 nm to 490 nm, specifically, an emission peak wavelength in the range of 464 nm to 472 nm. By using the silicate phosphors according to Examples 1 to 7 having a composition represented by formula (1) in a light-emitting device, the light-emitting device can increase the emission intensity in the range of 460 nm to 490 nm, where the emission intensity is at its minimum, resulting in a better spectral balance of the emission spectrum and the emission of light with high color reproducibility of the irradiated object. Furthermore, the silicate phosphors according to Examples 1 to 7 have a composition represented by formula (1) above, and when irradiated with excitation light having an emission peak wavelength in the range of 365 nm to 460 nm, they emit light in which the chromaticity coordinates (x, y) in the chromaticity diagram of the CIE1931 color system, measured from the emission spectrum of the silicate phosphor, are in the range of x being between 0.125 and 0.135, and y being between 0.100 and 0.200. When used in a light-emitting device, they can emit white light in which the x and y coordinates of the chromaticity diagram of the CIE1931 color system are within a specific range.

[0078] The silicate phosphors according to Examples 1 to 7 have an emission spectrum with a peak emission wavelength that has a full width at half maximum in the range of 36 nm to 50 nm, more specifically, in the range of 39 nm to 43 nm. By using the silicate phosphors according to Examples 1 to 7 having the composition represented by formula (1) in the light-emitting device, the light-emitting device can increase the emission intensity in the range of 460 nm to 490 nm, where the emission intensity is at its minimum, resulting in a better spectral balance of the emission spectrum and enabling the emission of light with high color reproducibility of the irradiated object.

[0079] The silicate phosphors in Examples 1 to 4 exhibit an emission energy value (relative emission energy) of 85% or more of the emission energy value of the emission spectrum at 200°C when irradiated with excitation light having an emission peak wavelength of 420 nm, with the emission energy value of the emission spectrum at 25°C being set to 100%. The silicate phosphors in Examples 1 to 7 maintain their emission intensity even at high temperatures, exhibit good temperature characteristics, and have high reliability.

[0080] The silicate phosphors according to Examples 1 to 7 have a central particle size of 50% of the cumulative volume-based particle size distribution measured by laser diffraction particle size distribution analysis, which is in the range of 5.0 μm to 25 μm, specifically 5.8 μm to 23.0 μm. The silicate phosphors according to Examples 1 to 7, having the composition represented by formula (1), readily diffuse light, and when used in a light-emitting device, can emit white light with x and y coordinates within a specific range on the chromaticity diagram of the CIE 1931 color system. Furthermore, by using the silicate phosphors according to Examples 1 to 7, having the composition represented by formula (1), in a light-emitting device, the silicate phosphor readily absorbs excitation light, and the light-emitting device can increase the emission intensity in the range of 460 nm to 490 nm, where the emission intensity is minimum, resulting in a better spectral balance of the emission spectrum and the emission of light with high color reproducibility of the irradiated object.

[0081] The silicate phosphor according to Comparative Example 1 does not contain Ca and does not have the composition represented by formula (1) above. The silicate phosphor according to Comparative Example 1 has an emission spectrum with an emission peak wavelength that has a full width at half maximum of less than 36 nm. It can be inferred that when the silicate phosphor according to Comparative Example 1 is used in a light-emitting device, the light-emitting device will not be able to increase the emission intensity in the range of 460 nm to 490 nm, where the emission intensity is at its minimum, in the emission spectrum of the light-emitting device.

[0082] As shown in Figure 5, the silicate phosphors in Examples 2 and 4 have a relative luminescence energy (%) of 85% or more at 200°C, exhibiting good temperature characteristics and high reliability. The silicate phosphor in Comparative Example 1 has a relative luminescence energy of less than 85% at 200°C, indicating that the luminescence energy is not maintained at high temperatures.

[0083] Light-emitting devices (Examples 1 to 7 and Comparative Example 1) A light-emitting device was fabricated containing each of the silicate phosphors described in the examples and comparative examples as the first phosphor. As the second phosphor, it has the composition represented by formula (2) above, and Lu3Al5O 12 A phosphor having a composition represented by :Ce (hereinafter also referred to as "LAG phosphor") was used. As the third phosphor, a phosphor having the composition represented by formula (3) above and the composition represented by (Sr,Ca)AlSiN3:Eu (hereinafter also referred to as "SCASN phosphor") and a phosphor having the composition represented by CaAlSiN3:Eu (hereinafter also referred to as "CASN phosphor") were used. A nitride-based semiconductor light-emitting element with an emission peak wavelength of 450 nm was used as the light-emitting element. A wavelength conversion component composition was prepared by dispersing the first phosphor, the second phosphor, and the third phosphor in a silicone resin in the proportions shown in Table 2. The wavelength conversion component composition was prepared by blending the first phosphor, the second phosphor, and the third phosphor in the proportions shown in Table 2, such that per 100 parts by mass of silicone resin, the first phosphor was 80 parts by mass, and the total amount of the second and third phosphors was 79.1 parts by mass or more and 88 parts by mass. The composition for the wavelength conversion member was prepared by adjusting the mixing ratios of the first phosphor, second phosphor, and third phosphor so that the mixed light of the light emitted from the light-emitting element and the light emitted from the wavelength conversion member emits light within the region FL (Frequency Line) enclosed by the chromaticity coordinates of the first point (x = 0.353 and y = 0.340), the second point (x = 0.338 and y = 0.353), the third point (x = 0.362 and y = 0.382), the fourth point (x = 0.378 and y = 0.369), the first straight line connecting the first and second points, the second straight line connecting the second and third points, the third straight line connecting the third and fourth points, and the fourth straight line connecting the fourth point and the first point. Figure 6 shows the chromaticity diagram of the CIE 1931 color system, illustrating the chromaticity coordinates of the first to fourth points mentioned above, and the region FL enclosed by the first to fourth lines. A first-configuration light-emitting device was manufactured using the aforementioned light-emitting element and wavelength conversion component composition. The light-emitting device of the first configuration example can be seen in Figure 1. Using lead frames as the first and second leads, the first and second leads were integrally molded using epoxy resin to prepare a molded body having a recess with sides and a bottom. A light-emitting element was placed on the bottom surface of the recess in the molded body, and the positive and negative electrodes of the light-emitting element were connected to the first and second leads using Au wires. Next, the prepared wavelength conversion component composition was filled into the recesses of the molded body. A wavelength conversion component composition filled into a recess in a molded body was heated at 150°C for 3 hours to cure it, thereby manufacturing a light-emitting device equipped with a wavelength conversion component containing a mixture of a first phosphor, a second phosphor, and a third phosphor.

[0084] Light-emitting device (Comparative Example 2) A light-emitting device was manufactured in the same manner as in the previously described examples, except that a silicate phosphor was not used and the first phosphor was not included. Table 2 shows the blending ratios of the second and third phosphors contained in the wavelength conversion member composition. Specifically, the first configuration light-emitting device was manufactured in the same manner as in the previously described examples, using the same wavelength conversion member composition as in the previously described examples, except that the second and third phosphors were blended in the proportions shown in Table 2, so that the total amount of the second and third phosphors was 80 parts by mass per 100 parts by mass of silicone resin.

[0085] Evaluation of light-emitting devices For each light-emitting device in Example and Comparative Example 1, using each silicate phosphor, and for each light-emitting device in Comparative Example 2, which does not use silicate phosphor, the emission spectra were measured using an optical measurement system combining a spectroscopic measuring device (OCM-510C, manufactured by Optocom Co., Ltd.) and an integrating sphere. The emission spectra of each light-emitting device were measured at room temperature (approximately 25°C, 20°C to 30°C). For each light-emitting device in Example and Comparative Example, the emission intensity at the minimum value of the emission spectrum (minimum emission intensity M(%)) was measured. In the emission spectra of each light-emitting device in Example and Comparative Example, the maximum emission intensity is the emission intensity at the emission peak wavelength of the light-emitting element, 450 nm. In the emission spectra of each light-emitting device in Example and Comparative Example, the minimum emission intensity is the emission intensity in the wavelength range of 470 nm to 480 nm. The difference (%) obtained by subtracting the minimum emission intensity M(%) of the light-emitting device in Comparative Example 2, which does not contain silicate phosphor, from the minimum emission intensity M(%) in the emission spectrum of each light-emitting device was defined as the improvement rate ΔM(%). Furthermore, the chromaticity coordinates (x, y) in the CIE 1931 color system chromaticity diagram were measured from the emission spectra of each light-emitting device. The results are shown in Table 2.

[0086] [Table 2]

[0087] The light-emitting devices according to Examples 1 to 7, using the silicate phosphors according to Examples 1 to 7, emit light within the aforementioned region FL, and the emission intensity in the range of 460 nm to 490 nm, where the emission intensity is minimum in the emission spectrum of the light-emitting device, more specifically in the range of 470 nm to 480 nm, can be made higher than that of the light-emitting device according to Comparative Example 2, which does not contain silicate phosphors. Furthermore, the light-emitting devices according to Examples 1 to 7 can achieve a higher emission intensity (minimum emission intensity M) at the minimum value in the emission spectrum of the light-emitting device compared to the light-emitting device according to Comparative Example 1, which contains a silicate phosphor that does not have the composition represented by formula (1), resulting in a better spectral balance of the emission spectrum and the emission of light with high color reproducibility of the irradiated object. The appearance color of the top surface of the light-emitting device according to Examples 1 to 7, using the silicate phosphors according to Examples 1 to 7, when not emitting light is visually confirmed to be white, compared to the visually confirmed yellow appearance color of the top surface of the light-emitting device according to Comparative Example 2, which does not contain the first phosphor, when not emitting light.

[0088] The light-emitting devices according to Examples 1 to 7 emit light within the aforementioned region FL, and in the emission spectrum of the light-emitting device, when the emission intensity at the emission peak wavelength of the light-emitting element where the emission intensity is maximum is set to 100%, the emission intensity in the range of 460 nm to 490 nm is the minimum value, and the minimum emission intensity is 25% or more. This makes it possible to increase the minimum emission intensity, improve the spectral balance of the emission spectrum, and emit light with high color reproducibility of the irradiated object.

[0089] The light-emitting devices of Examples 1 to 7 have been improved so that the minimum emission intensity in the emission spectrum of the light-emitting device, which is the minimum value of the emission intensity in the emission spectrum of the light-emitting device of Comparative Example 2 (which does not contain silicate phosphors), exceeds 5.0%, resulting in a higher minimum emission intensity in the emission spectrum of the light-emitting device. This improves the spectral balance of the emission spectrum and enables the emission of light with high color reproducibility of the irradiated object.

[0090] Figure 7 shows the emission spectrum of the light-emitting device according to Example 1 and the light-emitting spectrum of the light-emitting device according to Comparative Example 2. Figure 8 shows the emission spectrum of the light-emitting device according to Example 2 and the light-emitting spectrum of the light-emitting device according to Comparative Example 2. Figure 9 shows the emission spectrum of the light-emitting device according to Example 3 and the light-emitting spectrum of the light-emitting device according to Comparative Example 2. Figure 10 shows the emission spectrum of the light-emitting device according to Example 4 and the light-emitting spectrum of the light-emitting device according to Comparative Example 2. As shown in Figures 7 to 10, the minimum value in the emission spectrum of the light-emitting devices of Examples 1 to 4 is higher in emission intensity than the minimum value in the emission spectrum of the light-emitting device of Comparative Example 2.

[0091] Figure 11 shows the emission spectrum of the light-emitting device according to Example 5 and the emission spectrum of the light-emitting device according to Comparative Example 2. Figure 12 shows the emission spectrum of the light-emitting device according to Example 6 and the emission spectrum of the light-emitting device according to Comparative Example 2. Figure 13 shows the emission spectrum of the light-emitting device according to Example 7 and the emission spectrum of the light-emitting device according to Comparative Example 2. As shown in Figures 11 to 13, the minimum value in the emission spectrum of the light-emitting devices of Examples 5 to 7 is higher in emission intensity than the minimum value in the emission spectrum of the light-emitting device of Comparative Example 2.

[0092] Figure 14 shows the emission spectra of the light-emitting devices according to Comparative Examples 1 and 2. As shown in Figure 14, the minimum value in the emission spectrum of the light-emitting device according to Comparative Example 1, which includes the first phosphor, is higher in emission intensity than the minimum value in the emission spectrum of the light-emitting device according to Comparative Example 2, which does not include the first phosphor. However, since the light-emitting device according to Comparative Example 1 does not include the first phosphor, which contains a silicate phosphor having the composition represented by formula (1), the improvement rate ΔM (%) is smaller than that of the light-emitting devices according to Examples 1 to 7, with an improvement rate ΔM of 5.0%, and the spectral balance of the emission spectrum is not as improved as that of the light-emitting devices according to Examples 1 to 7.

[0093] Embodiments relating to this disclosure include the following silicate phosphors and light-emitting devices.

[0094] [Item 1] A silicate phosphor having a composition represented by the following formula (1). (Ca x Sr 1-x―y Ba y ) 3―z MgSi2O8:Eu z (1) (In the formula (1), x, y, and z satisfy 0 < x ≤ 0.5, 0 ≤ y ≤ 0.1, and 0 < z ≤ 0.3, respectively.) [Item 2] The silicate phosphor according to Item 1, wherein z in the formula (1) satisfies 0.01 ≤ z ≤ 0.295. [Item 3] The silicate phosphor according to Item 1 or 2, wherein x in the formula (1) satisfies 0.01 ≤ x ≤ 0.45. [Item 4] The silicate phosphor according to any one of Items 1 to 3, wherein the silicate phosphor has an emission peak wavelength in the range of 460 nm or more and 490 nm or less in the emission spectrum. [Item 5] The silicate phosphor according to Claim 4, wherein the full width at half maximum of the emission spectrum having the emission peak wavelength is in the range of 36 nm or more and 50 nm or less. [Item 6] When the excitation light having an emission peak wavelength of 420 nm is irradiated on the silicate phosphor, the emission energy value of the emission spectrum of the silicate phosphor at 200 °C is 85% or more when the emission energy value of the emission spectrum of the silicate phosphor at 25 °C is taken as 100%. The silicate phosphor according to any one of Items 1 to 5. [Item 7] The silicate phosphor according to any one of Items 1 to 6, wherein the cumulative 50% median diameter in the volume-based particle size distribution by the laser diffraction particle size distribution measurement method is in the range of 5.0 μm or more and 25 μm or less. [Item 8] A light-emitting device including the silicate phosphor according to any one of Items 1 to 7 and a light-emitting element that has an emission peak wavelength in the range of 365 nm or more and 460 nm or less and irradiates the silicate phosphor. [Section 9] The light-emitting device according to item 8, wherein, in the chromaticity diagram of the CIE1931 color system, it emits light within the region enclosed by a first point in the chromaticity coordinates where x is 0.353 and y is 0.340, a second point where x is 0.338 and y is 0.353, a third point where x is 0.362 and y is 0.382, a fourth point where x is 0.378 and y is 0.369, a first line connecting the first and second points, a second line connecting the second and third points, a third line connecting the third and fourth points, and a fourth line connecting the fourth point and the first point, and emits light such that, when the emission intensity of the emission peak wavelength of the light-emitting element in the range of 365 nm to 460 nm is taken as 100%, the minimum emission intensity in the emission spectrum of the light-emitting device in the range of 470 nm to 490 nm is 25% or more. [Section 10] A light-emitting apparatus according to item 8 or 9, comprising an aluminate phosphor having a composition represented by the following formula (2) and a nitride phosphor represented by the following formula (3). (Lu,Y,Gd,Tb)3(Al,Ga)5O 12 :Ce (2) (Sr,Ca)AlSiN3:Eu (3) [Section 11] The light-emitting device according to any one of claims 8 to 10, wherein the content of the silicate phosphor in the light-emitting device is within the range of 45% by mass or more and 55% by mass or less, based on 100% by mass of the total amount of phosphor contained in the light-emitting device. [Industrial applicability]

[0095] A silicate phosphor and a light-emitting device equipped with a silicate phosphor according to one aspect of the present invention can be suitably used in cameras mounted on electronic devices such as smartphones, light sources for illumination, LED displays, backlight sources for liquid crystal displays, traffic lights, illuminated switches, light sources for projectors, various sensors, and various indicators. [Explanation of Symbols]

[0096] 10: Light-emitting element, 11: Semiconductor element, 12: Substrate, 20: First lead, 30: Second lead, 40: Molded body, 42: Resin part, 50: Wavelength conversion member, 51: First layer, 52: Second layer, 53: Wavelength conversion layer, 54: Diffusion layer, 55: Wavelength conversion member, 60: Wire, 61: Conductive member, 70: Phosphor, 71: First phosphor, 72: Second phosphor, 73: Third phosphor, 80: Adhesive layer, 90: Coating member, 100, 200: Light-emitting device.

Claims

1. A silicate phosphor having a composition represented by the following formula (1). (Ca) ｘ Sr １－ｘ―ｙ Ba ｙ ) ３－ｚ Yes ２ O ８ :Eu ｚ (1) (In equation (1) above, x, y, and z satisfy 0 < x ≤ 0.5, 0 ≤ y ≤ 0.1, and 0 < z ≤ 0.3, respectively.)

2. The silicate phosphor according to claim 1, wherein z satisfies 0.01 ≤ z ≤ 0.295 in formula (1).

3. The silicate phosphor according to claim 1, wherein in formula (1), x satisfies 0.01 ≤ x ≤ 0.

45.

4. The silicate phosphor according to claim 1, wherein the silicate phosphor has an emission peak wavelength in the range of 460 nm to 490 nm in its emission spectrum.

5. The silicate phosphor according to claim 4, wherein the silicate phosphor has an emission spectrum with an emission peak wavelength whose full width at half maximum is in the range of 36 nm to 50 nm.

6. The silicate phosphor according to claim 1, wherein when the silicate phosphor is irradiated with excitation light having an emission peak wavelength of 420 nm, the emission energy value of the emission spectrum of the silicate phosphor at 200°C is 85% or more, with the emission energy value of the emission spectrum of the silicate phosphor at 25°C being 100%.

7. The silicate phosphor according to claim 1, wherein the central particle size of the cumulative 50% in the volume-based particle size distribution measured by laser diffraction particle size distribution analysis is in the range of 5.0 μm to 25 μm.

8. A light-emitting device comprising a silicate phosphor according to any one of claims 1 to 7, and a light-emitting element having an emission peak wavelength in the range of 365 nm to 460 nm, for irradiating the silicate phosphor.

9. The light-emitting device emits light within a region enclosed by a first point in the chromaticity coordinates of the CIE 1931 color system where x is 0.353 and y is 0.340, a second point where x is 0.338 and y is 0.353, a third point where x is 0.362 and y is 0.382, a fourth point where x is 0.378 and y is 0.369, a first line connecting the first and second points, a second line connecting the second and third points, a third line connecting the third and fourth points, and a fourth line connecting the fourth point and the first point, and emits light such that the minimum luminescence intensity in the emission spectrum of the light-emitting device within the range of 470 nm to 490 nm is 25% or more, when the luminescence intensity of the emission peak wavelength of the light-emitting element in the range of 365 nm to 460 nm is 100%.

10. The light-emitting device according to claim 8, comprising an aluminate phosphor having a composition represented by the following formula (2) and a nitride phosphor represented by the following formula (3). (L5,Y,Gd,Tb) ３ (Al, Ga) ５ O １２ :Ce (2) (Sr,Ca)-SiN ３ :Eu (3)

11. The light-emitting device according to claim 10, wherein the content of the silicate phosphor in the light-emitting device is within the range of 45% by mass or more and 55% by mass or less, based on 100% by mass of the total amount of phosphor contained in the light-emitting device.

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