Phosphor Plate

Abstract

The present invention relates to a phosphor plate, characterized in that it comprises a fired body containing (Y 1‑x‑y , Gd x , Ce y )3Al5O 12 particles and Al2O3 particles, where x and y satisfy 0.07 ≤ x ≤ 0.11 and 0.010 ≤ y ≤ 0.015 respectively. In the above-mentioned fired body, the average particle size of the (Y 1‑x‑y , Gd x , Ce y )3Al5O 12 particles is 4 μm or more and 6 μm or less. With respect to the total amount of 100 vol% of the (Y 1‑x‑y , Gd x , Ce y )3Al5O 12 particles and Al2O3 particles, the concentration of the (Y 1‑x‑y , Gd x , Ce y )3Al5O 12 particles is 20 vol% or more and 30 vol% or less. The ratio of the average particle size of the above-mentioned Al2O3 particles to the average particle size of the (Y 1‑x‑y , Gd x , Ce y )3Al5O 12 particles (Al2O3 / (Y 1‑x‑y , Gd x , Ce y )3Al5O 12 ) is 1 or more and 2 or less. The overall thickness of the above-mentioned fired body is 150 μm or more and 250 μm or less.

Description

Technical Field

[0001] The present invention relates to a phosphor plate for obtaining white light by converting the wavelength of light emitted from a light emitting diode (LED), and more particularly to a phosphor plate for high-brightness white lighting. Background Art

[0002] LEDs are suitable for mobile phones, various display devices, etc. from the viewpoints of power saving, long life, and small size. Furthermore, with the improvement of luminous efficiency in recent years, LEDs are also attracting attention for lighting applications and are rapidly becoming popular.

[0003] Currently, for white LED lighting, the mainstream method is to obtain white light by mixing the light emitted by a blue LED and the light emitted by a fluorescent body that receives the incident blue light and emits yellow, which is the complementary color of blue. For wavelength conversion components using such fluorescent bodies, fluorescent body powder is generally dispersed in resin, but in recent years, from the perspective of heat resistance, composites of fluorescent body powder and ceramics are often used.

[0004] However, in LED lighting that requires uniform luminous color, wavelength conversion components using the above-mentioned ceramic composites have a problem that color unevenness is easily generated.

[0005] In this regard, for example, in Patent Document 1, the following method for manufacturing a wavelength conversion component is disclosed as a method for manufacturing a wavelength conversion component with high luminous intensity and high light conversion efficiency, and the manufacturing method includes: preparing a molded body comprising a yttrium aluminum garnet-based phosphor having a composition represented by the following formula (I) and alumina particles having an alumina purity of 99.0 mass % or more; sintering the above-mentioned molded body once to obtain a first sintered body; and sintering the above-mentioned first sintered body for a second time by hot isostatic pressing (HIP) treatment to obtain a second sintered body.

[0006] (Y 1-a-b G a Ce b ) 3 Al 5 O 12 (I)

[0007] (In formula (I), a and b are 0≤a≤0.3 and 0<b≤0.022 respectively.)

[0008] Regarding the wavelength conversion component obtained by the manufacturing method, although it is recorded that the Ce activation amount b in formula (I) is preferably greater than 0 and less than 0.022 (0<b≤0.022), in the embodiments, only b is exemplified as less than 0.009. Based on this, in order to obtain the desired fluorescence wavelength when Ce is less than 0.009, a large amount of Gd doping is required. When used in an LED light-emitting device, there is a problem that the wavelength conversion efficiency decreases as the temperature rises.

[0009] In addition, Patent Document 1 states that the average particle sizes of the yttrium aluminum garnet phosphor and alumina particles at the stage of preparing a molded body are preferably greater than 1 μm and less than 50 μm and greater than 0.2 μm and less than 1.3 μm, respectively, but there is no record of the sintered body particles after sintering. It cannot be said that sufficient research has been conducted on topics such as maximizing the luminous efficiency of the yttrium aluminum garnet phosphor and reducing chromaticity changes, orientation characteristics, and in-plane uniformity (reducing color unevenness) caused by scattering of the sintered body due to composite alumina particles.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: Japanese Patent Application Publication No. 2018-172628 Summary of the invention

[0013] Technical problem that the invention aims to solve

[0014] Although wavelength conversion members with high luminous intensity and light conversion efficiency have been obtained so far, further improvements are required in terms of chromaticity, orientation characteristics, and color unevenness.

[0015] An object of the present invention is to provide a phosphor plate that has a large luminous flux, can emit white light with a small decrease in luminous efficiency and a small chromaticity difference even when the temperature rises, and can suppress in-plane unevenness.

[0016] Technical solutions to the problem

[0017] The phosphor plate of the present invention is characterized by comprising (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 Particles and Al 2 O 3 The sintered body of the particles, x and y respectively satisfy 0.07≤x≤0.11 and 0.010≤y≤0.015, in the sintered body, the above (Y 1-x-y , Gd x , Ce y )3 Al 5 O 12 The average particle size of the particles is 4 μm or more and 6 μm or less. 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 Particles and Al 2 O 3 The total amount of particles is 100 vol%, (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 The concentration of the particles is 20 vol% or more and 30 vol% or less, and the Al 2 O 3 The average particle size of the particles is similar to the above (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 The average particle size ratio of Al 2 O 3 / (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 is 1 or more and 2 or less, and the entire thickness of the sintered body is 150 μm or more and 250 μm or less.

[0018] The ratio x / y of Gd to Ce contained in the phosphor plate is preferably 5.8 or more and 9.24 or less.

[0019] The porosity of the sintered body is preferably 1.0% or less.

[0020] Effects of the Invention

[0021] According to the present invention, it is possible to provide a phosphor plate that has a large luminous flux, suppresses a decrease in luminous efficiency due to a temperature rise, and emits white light with a small chromaticity difference. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic cross-sectional view of a fired body forming the phosphor plate of the present invention.

[0023] Explanation of symbols

[0024] 1 Sintered body

[0025] 2 Incident surface

[0026] 3 exit surface

[0027] 4 Side

[0028] 5 Side DETAILED DESCRIPTION

[0029] Hereinafter, the phosphor plate of the present invention will be described in detail.

[0030] The phosphor plate of the present invention comprises (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 Particles and Al 2 O 3 The sintered body of the particles, x and y respectively satisfy 0.07≤x≤0.11 and 0.010≤y≤0.015, in the above sintered body, (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 The average particle size of the particles is 4 μm or more and 6 μm or less. 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 Particles and Al 2 O 3 The total amount of particles is 100 vol%, (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 The concentration of the particles is 20 vol% or more and 30 vol% or less, and the Al 2 O 3 The average particle size of the particles is similar to the above (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 The average particle size ratio of Al 2 O 3 / (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12It is 1 or more and 2 or less, and the entire thickness of the sintered body is 150 μm or more and 250 μm or less.

[0031] In order to obtain the desired white light, in the yttrium aluminum garnet (YAG) series phosphor (hereinafter also referred to as "phosphor"), it is necessary to control the fluorescence wavelength by the doping amount of Gd and Ce. If a large amount of Gd is doped, the temperature characteristics of the phosphor are reduced. The temperature characteristic refers to the temperature dependence of the wavelength conversion efficiency. The reduction in temperature characteristics means that the wavelength conversion efficiency decreases when the temperature rises, which becomes a factor in the reduction of luminous flux when used at high temperatures. The wavelength conversion efficiency of ordinary phosphors decreases when the temperature rises, so there is a problem with the temperature characteristic. On the other hand, a high temperature characteristic means that even if the temperature rises, the reduction in wavelength conversion efficiency is small. In addition, in this specification, luminous flux is an indicator of the brightness of white light obtained when a phosphor plate is installed on a blue LED and white light is emitted.

[0032] On the other hand, if a large amount of Ce as a light-emitting element is doped, the amount of light absorbed increases. Therefore, in order to allow blue light to pass through, it is necessary to reduce the thickness and content of the phosphor. However, if the phosphor is too thin, the blue light cannot be fully diffused in the phosphor, and chromaticity difference causes problems. Chromaticity difference is an indicator of the orientation characteristics of white light. It is the chromaticity difference between the straight light (0 degrees) and the oblique light (60 degrees) of the white light obtained when the phosphor plate is installed on the blue LED and white light is emitted (ΔCIE_x = CIE_x (60 degrees) - CIE_x (0 degrees)). In order to obtain high-brightness white light, it is preferred that the chromaticity difference (orientation characteristic) is small. If the content of the phosphor is reduced excessively, the luminous flux is reduced due to the absorption of mixed materials such as aluminum oxide.

[0033] On the other hand, if Ce is excessively doped, the efficiency of converting blue light into yellow light decreases due to concentration quenching, which in turn reduces the luminous efficiency.

[0034] The (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 There are also appropriate values ​​for the doping amounts of Gd and Ce in the YAG particles (hereinafter also referred to as "YAG particles"). 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 If part of the Y site is replaced by Gd, the wavelength becomes long, and if part of the Al site is replaced by Gd, the wavelength becomes short. 1-x-y , Gd x , Cey ) 3 Al 5 O 12 If part of the Y site is replaced by Ce, 5d-4f allows migration and thus shows luminescence in a wider wavelength range. Based on these insights, the Gd content x and Ce content y obtained are 0.07≤x≤0.11 and 0.010≤y≤0.015, preferably 0.07≤x≤0.10 and 0.011≤y≤0.014. 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 In the particles, by setting x and y to be within the above numerical ranges, white light emission having a large luminous flux, high temperature characteristics, and a small chromaticity difference can be obtained.

[0035] When x is less than 0.07, y must be greater than 0.015 to obtain the desired white light. If y exceeds 0.015, the luminous efficiency decreases and the luminous flux decreases. On the other hand, when x exceeds 0.11, y must be less than 0.010 to obtain the desired white light, and the temperature characteristics decrease.

[0036] The average particle size of the YAG particles in the sintered body is greater than 4 μm and less than 6 μm, preferably greater than 4.4 μm and less than 5.6 μm. The above average particle size is obtained by using a field emission scanning electron microscope (FE-SEM) to photograph the surface of the sintered body, observing its reflected electron image and measuring the particle size. (According to ISO13383-1: 2012) Specifically, using the above-mentioned Hitachi High-Tech FE-SEM, a 2000-fold reflected electron image of the cross-sectional structure of the sintered body is taken, and the maximum particle length of 200 particles observed therein is measured, and the average value is calculated to obtain the average particle size. When the average particle size is greater than 4 μm and less than 6 μm, the YAG particles are uniformly dispersed in the sintered body. If the YAG particles are uniformly dispersed, there are fewer voids in the phosphor plate, and a high light conversion efficiency can be obtained.

[0037] If the average particle size is less than 4 μm, the crystallinity of the YAG particles as the phosphor component in the sintered body is low, the luminous efficiency is reduced, and the luminous flux is reduced. If the average particle size exceeds 6 μm, the blue light cannot be fully diffused in the phosphor, the chromaticity difference (ΔCIE_x) becomes larger, and the whiteness is reduced.

[0038] Relative to the YAG particles and Al in the sintered body 2 O 3The total amount of particles is 100 vol%, and the concentration of YAG particles is 20 vol% or more and 30 vol% or less, preferably 22 vol% or more and 26 vol% or less. The concentration of YAG particles is calculated by XRD diffraction analysis of the phosphor plate to determine the YAG phase and Al 2 O 3 The phase ratio is thus determined.

[0039] If the concentration of YAG particles is less than 20 vol%, due to Al 2 O 3 On the other hand, when Al exceeds 30 vol%, the light flux decreases. 2 O 3 The scattering in the layer becomes insufficient, the chromaticity difference decreases, that is, the orientation characteristics deteriorate, and color unevenness occurs. It should be noted that color unevenness refers to the chromaticity deviation within the phosphor plate surface when the phosphor plate is installed on the blue LED and emits white light. The smaller the value, the more homogeneous the white light obtained.

[0040] In addition, Al 2 O 3 The particles are components other than the YAG particles that constitute the sintered body, so their concentration is relatively high compared to the YAG particles and Al 2 O 3 The total amount of the particles is 80 to 70 vol%, preferably 78 to 74 vol%, 100 vol%. Al 2 O 3 The concentration of particles can also be determined by XRD diffraction analysis of the phosphor plate.

[0041] Al 2 O 3 The ratio of the average particle size of the particles to the average particle size of the YAG particles (Al 2 O 3 Average particle size / average particle size of YAG) is 1 to 2. When the above ratio is 1 to 2, the phosphor plate becomes a highly efficient light-emitting element.

[0042] However, in Al 2 O 3 When the average particle size / YAG average particle size is less than 1, that is, in the case of Al 2 O 3 When the particles are smaller than YAG particles on average, YAG particles have high luminous efficiency, but due to the blue light and fluorescence in Al 2 O 3 There is excessive scattering in the particles, so the extraction efficiency is reduced and the light flux is reduced. 2 O 3 When the average particle size / YAG average particle size exceeds 2, that is, in Al2 O 3 When the particles are larger than YAG particles on average, the luminous efficiency of the phosphor plate decreases, and the luminous flux decreases. In addition, since the white light after wavelength conversion is not sufficiently diffused and emitted, color unevenness occurs.

[0043] The method for producing the sintered body of the present invention is not particularly limited, and for example, the following method can be used: 2 O 3 (average particle size 0.3 to 3 μm), CeO 2 (average particle size 0.1 to 1 μm), Gd 2 O 3 (average particle size 0.2~4μm) and Al 2 O 3 (average particle size 0.2 to 10 μm) as a raw material, appropriately determine the average particle size, and when a sintered body is made, appropriately mix it in a manner to form a prescribed composition, and after molding and degreasing, at 1.0×10 -2 The sintering is performed in a vacuum atmosphere of medium vacuum to low vacuum level below Pa. A cross-sectional view of the sintered body is shown in FIG. Figure 1 .like Figure 1 As shown, the phosphor plate of the present invention is a plate-shaped body whose main surface is a light incident surface 2 and whose main surface opposite to the incident surface 2 is a light emitting surface 3.

[0044] The incident surface 2 and the exit surface 3 are YAG particles and Al 2 O 3 The fired surface of the particle exposed in the non-processed state. Non-processed means that after the raw material powder is formed, the fired state is maintained, and it means that no mechanical grinding, etching or other processing is performed after firing. In addition, if the incident surface 2 and the exit surface 3 are subjected to mechanical grinding, etching or other processing after firing to form a so-called processed surface, the mechanical strength is low, and cracks caused by stress are easily generated during installation or use. In addition, due to defects generated during processing, it is possible to cause undesirable conditions such as reduced luminous efficiency.

[0045] The arithmetic mean roughness (Ra) of the sintered body of the phosphor plate of the present invention at a measured length of 4 mm is preferably 0.15 μm or more and 1.00 μm or less. This improves light extraction efficiency and can increase luminous flux. The Ra is measured in accordance with JIS B 0601:1994.

[0046] The overall thickness of the sintered body is 150 μm to 250 μm, preferably 180 μm to 230 μm. When the thickness is less than 150 μm, scattering becomes insufficient and the chromaticity difference worsens. On the other hand, when the thickness exceeds 250 μm, scattering is high, extraction efficiency is reduced, and luminous flux is reduced. Extraction efficiency refers to the efficiency when blue light and yellow light are output from the phosphor plate, and the product of luminous efficiency and extraction efficiency is an indicator of the performance of the phosphor.

[0047] The Gd / Ce ratio x / y in the sintered body is preferably 4 to 15, preferably 5.8 to 9.24, and more preferably 6.5 to 8.0.

[0048] When the Gd / Ce ratio x / y is less than 4, the Gd concentration is low, and the emission may be shorter than the desired fluorescence wavelength. Alternatively, when the Ce concentration is high, the luminous efficiency decreases due to concentration quenching, and the luminous flux may decrease. On the other hand, when the Gd / Ce ratio x / y exceeds 15, the Gd concentration is high and the Ce concentration is low, so the temperature characteristics may decrease.

[0049] By setting the Gd / Ce ratio x / y in the sintered body to 5.8 or more and 9.24 or less (more preferably 6.5 or more and 8.0 or less), a more accurate fluorescence wavelength can be obtained, the reduction of luminous efficiency caused by concentration quenching can be prevented, and a higher luminous flux can be obtained. Furthermore, the temperature characteristics can be further improved.

[0050] The porosity of the sintered body is preferably 1.0% or less. By making the porosity 1.0% or less, the phosphor plate can have high mechanical strength. In addition, it is possible to prevent excessive scattering of incident light, thereby increasing the proportion of return light to the incident surface 2 side and preventing a decrease in luminous efficiency. It should be noted that the porosity is measured in accordance with JIS R1634:1998.

[0051] [Example]

[0052] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to the examples shown below.

[0053] 〔1〕[(Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 +Al 2 O 3 ]Production of fired body

[0054] Cerium oxide powder with an average particle size of 0.5 μm and a purity of 99.9%, yttrium oxide powder with an average particle size of 1.2 μm and a purity of 99.9%, gadolinium oxide powder with an average particle size of 0.9 μm and a purity of 99.9%, and aluminum oxide powder with an average particle size of 0.5 μm and a purity of 99.9% are mixed at a predetermined mixing ratio to obtain a raw material powder. The particle sizes of the yttrium oxide powder, gadolinium oxide powder, cerium oxide powder, and aluminum oxide powder are adjusted to obtain ((Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 +Al 2 O 3 ) in the sintered body (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 Particles and Al 2 O 3 Specifically, when adjusting (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 In the case of the average particle size of the particles, the particle sizes of the yttrium oxide powder, the gadolinium oxide powder and the cerium oxide powder in the raw material powder are adjusted, and the Al 2 O 3 In the case of the average particle size of the particles, the particle size of the alumina powder in the raw material powder is adjusted.

[0055] Ethanol, a polyvinyl butyral (PVB)-based binder, and a glycerin-based plasticizer were added to the raw material powder, and the mixture was pulverized and mixed for 40 hours using a ball mill using alumina balls to prepare a slurry.

[0056] The slurry was used to form a green sheet of a specified thickness by a doctor blade method. At this time, the thickness of the green sheet was adjusted to adjust the overall thickness of the phosphor plate. The green sheet was degreased and pre-fired in the atmosphere and then heated to 1.0 × 10 -2 Pa or less vacuum atmosphere at 1700 ° C to obtain ((Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 +Al 2 O 3 ) fired body.

[0057] By appropriately adjusting the above conditions, samples of Examples 1 to 9 and Comparative Examples 1 to 14 described in Table 1 were prepared and the following evaluations were performed.

[0058] 〔2〕[(Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 +Al 2 O 3 Evaluation of fired body

[0059] (Ce, Gd concentration)

[0060] The Ce concentration and Gd concentration of the obtained phosphor plate were determined by ICP emission analysis.

[0061] (Average particle size)

[0062] The reflected electron image of the surface of the phosphor plate was taken using a field emission scanning electron microscope (FE-SEM) to determine the YAG particles and Al 2 O 3 Then, the average value of the maximum length of each particle is taken as the average particle size (unit: μm). 2 O 3 The number of particles was more than 200.

[0063] ((Y 1-x-y , Gdx, Ce y ) 3 Al 5 O 12 ratio)

[0064] The ratio of YAG particles to Al was calculated by XRD diffraction analysis of the phosphor plate. 2 O 3 The phase ratio is thus determined.

[0065] (Dominant wavelength)

[0066] The phosphor plate was cut into 10 mm squares and placed in the center of a 4-inch integrating sphere. A xenon lamp was split into 450 nm ± 1 nm wavelength excitation light using a spectrometer and irradiated onto the integrating sphere. A spectrometer ("Fiber Optic Multi-Channel Spectrometer USB4000" manufactured by Ocean Insight) was used to measure the emission spectrum of the phosphor plate, and the main wavelength of fluorescence was calculated for the fluorescence component of 480 to 780 nm in the obtained emission spectrum.

[0067] (Temperature characteristics)

[0068] The above-mentioned phosphor plate (10 mm × 10 mm) was placed in the center of a 4-inch integrating sphere with a heater, and irradiated with excitation light of 450 nm ± 1 nm in the same manner as the fluorescence wavelength measurement, and the quantum efficiency at 25°C and 200°C was measured from the emission spectrum of the phosphor plate. The value obtained by dividing the quantum efficiency at 200°C by the quantum efficiency at 25°C was taken as the temperature characteristic.

[0069] (Luminous flux)

[0070] After processing the phosphor plate into a size of 1 mm square, it was fixed on a blue LED element (luminous area 1 mm square, luminous wavelength 450 nm) with silicone resin. After focusing the luminous light with a 4-inch integrating sphere, a spectrometer ("Fiber Multi-channel Spectrometer USB4000" manufactured by OceanInsight) was used to measure the luminous spectrum.

[0071] The luminous flux was calculated from the obtained emission spectrum. The relative luminous flux value was calculated for the same type of LED, with the luminous flux of 22 vol% of commercially available YAG:Ce phosphor (P46-Y3 manufactured by Kasei Optronics (now Mitsubishi Chemical High-Technica)) powder fixed in commercially available phenyl silicon (OE-6630 manufactured by Dow Corning) resin being set as 100.

[0072] (chromaticity difference)

[0073] After processing the phosphor plate into a size of 1 mm square, it was fixed on a blue LED element (luminous area 1 mm square, luminous wavelength 450 nm) with silicone resin. The chromaticity CIE_x of the front direction (0 degrees) and the oblique direction (60 degrees) of the luminescence from the phosphor plate was measured, and the value of CIE_x (60 degrees) - CIE_x (0 degrees) was taken as the chromaticity difference (ΔCIE_x). The smaller the chromaticity difference, the better the orientation (orientation characteristics) of the white light.

[0074] (Uneven color)

[0075] The phosphor plate was processed into a size of 1 mm square and fixed on a blue LED element (luminous area 1 mm square, luminous wavelength 450 nm) with silicone resin. The color unevenness of the phosphor plate luminous surface was measured with a two-dimensional colorimeter (CA-2500 manufactured by KONICA MINOLTA), and the difference between the maximum and minimum values ​​of CIE_x was taken as the color unevenness.

[0076] [Table 1]

[0077]

[0078] According to the above results, it can be confirmed that in (Y1-x-y , Gd x , Ce y ) 3 Al 5 O 12 In the particles, by satisfying 0.07≤x≤0.11 and 0.010≤y≤0.015, a phosphor plate having excellent orientation characteristics, luminous flux, and temperature characteristics can be obtained.

[0079] It can be confirmed that by making (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 The average particle size of the particles is 4 μm or more and 6 μm or less, and a phosphor plate having excellent orientation characteristics and luminous flux can be obtained.

[0080] It can be confirmed that by making (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 When the concentration of the particles is 20 vol% or more and 30 vol% or less, a phosphor plate having excellent luminous flux, orientation characteristics, and color unevenness can be obtained.

[0081] It can be confirmed that by 2 O 3 The average particle size of the particles is similar to the above (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 The average particle size ratio of Al 2 O 3 / (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 By setting the ratio to be 1 or more and 2 or less, a phosphor plate having excellent luminous flux and color unevenness can be obtained.

[0082] It was confirmed that by setting the total thickness of the fired body to 150 μm or more and 250 μm or less, a phosphor plate having excellent luminous flux and orientation characteristics can be obtained.

[0083] It was confirmed that by setting the Gd / Ce ratio x / y to 5.8 or more and 9.24 or less, a phosphor plate having excellent luminous flux and temperature characteristics can be obtained.

[0084] This application is based on Japanese patent application No. 2020-218582 filed on December 28, 2020 and Japanese patent application No. 2021-162683 filed on October 1, 2021, the entire contents of which are incorporated herein by reference.

Claims

1. A phosphor plate, It is characterized in that is a 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 Particles and Al 2 O 3 A phosphor plate of a sintered body of particles, x and y satisfy 0.07≤x≤0.11 and 0.010≤y≤0.015 respectively, In the sintered body, (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 The average particle size of the particles is 4 μm or more and 6 μm or less. Relative to (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 Particles and Al 2 O 3 The total amount of particles is 100 vol%, (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 The concentration of the particles is 20 vol% or more and 30 vol% or less, The Al 2 O 3 The average particle size of the particles is 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 The ratio of the average particle size of the particles is 2 O 3 / (Y 1-x-y , Gd x , Ce y ) 3 Al 5 O 12 is greater than 1 and less than 2, The entire thickness of the sintered body is 150 μm or more and 250 μm or less.

2. The phosphor plate according to claim 1, in, The Gd / Ce content ratio x / y in the phosphor plate is 5.8 or more and 9.24 or less.

3. The phosphor plate according to claim 1 or 2, in, The sintered body has a porosity of 1.0% or less.

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