Phosphor, fluorescent member and light-emitting module

Abstract

This fluorescent material has a garnet-type crystal structure and is represented by the general formula BaaY3-a-bAl5-aSiaO12:Ceb (where a and b satisfy 12.0113 ≤ A + 0.036b - 0.003a ≤ 12.0153 when the lattice size of the crystal structure is A, the solid solution amount of Ba is a [mol], and the solid solution amount of Ce is b [mol]).

Description

[Technical Field]

[0001] The present invention relates to a phosphor. [Background technology]

[0002] Conventionally, white light sources that combine YAG phosphors and blue LEDs have been widely known. However, as the brightness of light sources has increased, thermal quenching has occurred due to heat concentration caused by wavelength conversion (Stokes loss) in the YAG phosphor, resulting in a decrease in the efficiency of the white light source. To address this issue, we have developed BaY, a solid solution of Ba and Si in YAG phosphor. 1.92 Al4SiO 12 :Ce 0.08 This phosphor is different from the conventional YAG phosphor (Y3Al5O 12 It has better temperature characteristics than ZnO (Ce), and when heated from 25°C to 200°C, the luminescence intensity retention rate is 91.5%, making it less susceptible to thermal quenching. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Haipeng Ji et al., "New Y2BaAl4SiO12:Ce3+ yellow microcrystal-glass powder phosphor with high thermal emission stability", Journal of Materials Chemistry C, 2016, 4, pp.9872-9878 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the aforementioned BaY 1.92 Al4SiO 12 :Ce 0.08Therefore, there is a limit to the chromaticity range that can be achieved by combining this yellow phosphor with a blue LED as a white light source.

[0005] The present invention has been made in view of the above circumstances, and one of its objects is to provide a novel phosphor. [Means for solving the problem]

[0006] In order to solve the above problems, a phosphor according to one embodiment of the present invention has a garnet-type crystal structure and is represented by the general formula Ba a Y 3-a-b Al 5-a Si a O 12 :Ce b (However, if the lattice size of the crystal structure is S, the amount of solid solution of Ba is a [mol], and the amount of solid solution of Ce is b [mol], a and b are values ​​in the range that satisfies 12.0113≦S+0.036b-0.003a≦12.0153.)

[0007] According to this embodiment, a novel phosphor having good light-emitting properties and temperature characteristics can be realized.

[0008] The phosphor may be excited by blue light having a peak wavelength in the range of 430 to 480 nm and emit yellow light having a dominant wavelength in the range of 567 to 572 nm, thereby realizing a novel yellow phosphor.

[0009] The amount of solid solution of Ba, a [mol], may be 1.0 or less.

[0010] The volume average particle size may be 1 to 30 μm.

[0011] Another aspect of the present invention is a fluorescent member. The fluorescent member may include a phosphor powder that is a powder of the above-described phosphor, and a thermally conductive powder that is a powder of a material having a thermal conductivity higher than that of the phosphor.

[0012] According to this aspect, the heat dissipation properties of the fluorescent member can be improved.

[0013] The volume ratio of the phosphor powder to the thermally conductive powder may be 90: 10 to 60: 40. This can improve the heat dissipation properties of the fluorescent member and enhance the light emitting performance of the fluorescent member.

[0014] The phosphor powder may absorb light with a peak wavelength of 450 nm, the thickness of the fluorescent member may be 0.12 to 0.30 mm, and the transmittance of the fluorescent member for light with a wavelength of 550 to 600 nm may be 70% or more, thereby increasing the mechanical strength of the fluorescent member and realizing light suitable for a desired application (for example, a headlamp).

[0015] The phosphor powder may absorb blue light with a peak wavelength of 450 nm, and the fluorescent member may have an absorptivity of 78 to 88% for blue light, thereby achieving light suitable for a desired application (for example, a headlamp).

[0016] The fluorescent member may include a resin that is transparent to visible light and a fluorescent material encapsulated in the resin. The phosphor may be contained in the resin at 0.1 to 30 vol % and the thickness of the fluorescent member may be 0.01 to 5 mm. This makes it possible to realize a light-emitting module that achieves a desired luminous efficiency and emits light with a chromaticity within a desired range.

[0017] Yet another aspect of the present invention is a light-emitting module. This light-emitting module includes an LED that emits blue light with a peak wavelength in the range of 430 to 480 nm, and an optical wavelength conversion layer that is excited by the blue light emitted by the LED and emits yellow light. The optical wavelength conversion layer includes the above-mentioned fluorescent material. This light-emitting module emits light with a color obtained by mixing the blue light and the yellow light, and the chromaticity falls within the range surrounded by chromaticity coordinates (cx, cy) = (0.311, 0.339), (0.313, 0.342), (0.331, 0.354), (0.331, 0.338), (0.319, 0.315), and (0.311, 0.309).

[0018] Any combination of the above components, and conversion of the present invention between a manufacturing method, a lighting fixture or lighting device, a light emitting module, a light source, etc. are also valid aspects of the present invention. [Effects of the Invention]

[0019] According to the present invention, a novel phosphor can be provided. [Brief explanation of the drawings]

[0020] [Figure 1] This is a chromaticity diagram (CIE1931) showing the chromaticity of the emitted color of a conventional yellow phosphor and a blue LED. [Figure 2] FIG. 4 is a diagram for explaining a range of dominant wavelengths targeted by a yellow phosphor according to the present embodiment. [Figure 3] FIG. 1 is a graph showing the relationship between the amount of Ce in solid solution (b) and the dominant wavelength λd when the amount of Ba in solid solution (a) is constant. [Figure 4] FIG. 10 is a graph showing the relationship between the amount of Ba in solid solution (a) and the dominant wavelength λd when the amount of Ce in solid solution (b) is constant. [Figure 5] FIG. 1 is a diagram showing the relationship between the amount of Ce solid solution (b) and the lattice size S when the amount of Ba solid solution (a) is constant. [Figure 6] FIG. 1 is a diagram showing the relationship between the amount of Ba in solid solution (a) and the lattice size S when the amount of Ce in solid solution (b) is constant. [Figure 7] FIG. 1 is a diagram showing the relationship between the lattice size S and the dominant wavelength λd when the amount of Ba in solid solution is constant. [Figure 8] FIG. 10 is a diagram showing the relationship between the correction grating size S′ and the dominant wavelength λd. [Figure 9] 1 is a schematic diagram of a light-emitting module according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing will be given the same reference numerals, and redundant explanations will be omitted where appropriate. Furthermore, the embodiments are illustrative and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

[0022] [Phosphor] The phosphor according to this embodiment is a phosphor that is efficiently excited by blue light and emits light. Specifically, it is a phosphor that is strongly excited by blue light having a peak wavelength in the range of 430 to 480 nm and emits yellow light having a dominant wavelength in the range of 567 to 572 nm. In addition, the phosphor according to this embodiment has a garnet-type crystal structure and contains Ce 3+ Yellow light emission is achieved by doping with activators such as ions.

[0023] Next, the phosphor according to this embodiment will be described in detail. The phosphor according to this embodiment has the general formula Ba a Y 3-a-b Al 5-a Si a O 12 :Ce b (where S is the lattice size of the crystal structure, a [mol] is the amount of solid solution of Ba, and b [mol] is the amount of solid solution of Ce, and a and b are values ​​within the range that satisfies 12.0113≦S+0.036b−0.003a≦12.0153). Here, b may be 0.01 to 0.12. This allows the internal quantum efficiency, absorptivity, and luminous intensity maintenance rate of the phosphor to be further improved.

[0024] Figure 1 is a chromaticity diagram (CIE 1931) showing the chromaticity of the emitted color of a conventional yellow phosphor and a blue LED. Point C1 in Figure 1 corresponds to the chromaticity of a known phosphor (BaY) in which Ba and Si are solid-solved in a YAG phosphor. 1.92 Al4SiO 12 :Ce 0.08) and the dominant wavelength of this known phosphor is 566.3 nm. Meanwhile, point C2 is the chromaticity coordinate of an example of a blue LED whose peak wavelength is in the range of 430 to 480 nm.

[0025] Range R1 is the chromaticity range defined as the white light for a specific application (vehicle headlights). Specifically, range R1 is the range bounded by chromaticity coordinates (cx, cy) = (0.311, 0.339), (0.313, 0.342), (0.331, 0.354), (0.331, 0.338), (0.319, 0.315), and (0.311, 0.309).

[0026] The mixed color light obtained by combining the yellow light from a known phosphor with the blue light from an LED has a chromaticity on the line connecting points C1 and C2. Therefore, as shown in Figure 1, if the dominant wavelength of the yellow light is on the long wavelength side, white light falling within range R1 cannot be achieved unless the blue LED is changed. Therefore, a phosphor with a dominant wavelength shifted to the long wavelength side compared to conventional yellow phosphors, such as the yellow-light phosphor of the present invention, is required.

[0027] 2 is a diagram illustrating the range of dominant wavelengths targeted by the yellow phosphor according to this embodiment. In order for the yellow phosphor according to this embodiment to achieve the chromaticity range defined as the white light for vehicle headlights in combination with a blue LED, it is necessary that the line connecting the chromaticity (cx2, cy2) of the blue LED and the chromaticity (cx1, cy1) of the yellow phosphor pass through range R1.

[0028] According to the inventors' investigations, when a line connecting the chromaticity (cx2, cy2) of the blue LED at point C2 and the chromaticity (cx1', cy1') of the yellow phosphor at point C1' meets at the top of the chromaticity range R1, the dominant wavelength is 567.4 nm. Similarly, when a line connecting the chromaticity (cx2, cy2) of the blue LED at point C2 and the chromaticity (cx1", cy1") of the yellow phosphor at point C1" meets at the bottom of the chromaticity range R1, the dominant wavelength is 570.6 nm.

[0029] Therefore, the yellow phosphor according to this embodiment preferably has a dominant wavelength in the range of 567 to 572 nm, and more preferably has a dominant wavelength in the range of 567.4 to 570.6 nm.

[0030] The following provides a more detailed explanation using the measurement results of samples with different phosphor compositions, but the following descriptions of the raw materials, manufacturing methods, chemical compositions, etc. of the phosphors do not in any way limit the embodiments of the phosphors of the present invention.

[0031] (Sample 1) The phosphor of Sample 1 is Ba 1.00 Y 1.92 Al 4.00 Si 1.00 :Ce 3+ 0.08 The phosphor of Sample 1 is manufactured by the following method. First, powder raw materials of BaCO3 (99.9%: manufactured by Kanto Chemical Co., Ltd.), Y2O3 (99.9%: manufactured by Kojundo Chemical Laboratory Co., Ltd.), CeO2 (99.99%: manufactured by Kojundo Chemical Laboratory Co., Ltd.), α-Al2O3 (99.99%: manufactured by Kojundo Chemical Laboratory Co., Ltd.), and SiO2 (99.9%: manufactured by Tokuyama Corporation) are prepared. Then, each powder raw material is weighed out so that the molar ratios are Ba = 0.01, Y = 2.97, Al = 4.99, Si = 0.01, and Ce = 0.02.

[0032] BaF2 (99%, manufactured by Kojundo Chemical Laboratory Co., Ltd.) was used as a flux, and 5 wt% of the total weight of the powder raw materials was weighed out and combined with the powder raw materials. They were then uniformly mixed in a mortar. They were then placed in an alumina crucible (SSA-S B1, manufactured by Nikkato Corporation) and heated to 1550°C for 4 hours in a reducing atmosphere (H2:N2 = 5 / 95 (vol ratio)) for sintering. After cooling to room temperature, they were crushed in a mortar and the luminescence characteristics of the phosphor excited with light at a wavelength of 460 nm were measured using a spectrophotometer (FP-8500, manufactured by JASCO Corporation).

[0033] As a result, the dominant wavelength λd of the phosphor of Sample 1 was 567.0 nm, and the luminous intensity maintenance rate (K) when the temperature was raised from 25°C to 200°C was evaluated to be 89%. In other words, the luminous intensity when the temperature was raised to 200°C decreased to 89% compared to the luminous intensity at 25°C. In addition, the internal quantum efficiency (IQE) was 98%, and the absorptance (Abs) of the blue light emitted by the LED by the yellow-emitting phosphor was 78%.

[0034] The results of the emission characteristics, temperature characteristics, etc. of the phosphor of Sample 1 are summarized in Table 1. In Table 1, the case where the dominant wavelength λd satisfies 567.4 nm≦λd≦570.6 nm is marked with an O, and the case where it does not is marked with an X. Furthermore, the emission intensity maintenance rate (K) is marked with an O if it is 90% or more, and marked with an X if it is less than 90%. Furthermore, the internal quantum efficiency (IQE) is marked with an O if it is 90% or more, and marked with an X if it is less than 90%. Furthermore, the absorptivity (Abs) is marked with an O if it is 80% or more, and marked with an X if it is less than 80%.

[0035] [Table 1]

[0036] (Samples 2 to 35) The phosphors of Samples 2 to 35 are represented by the general formula Ba a Y 3-a-b Al 5-a Si a O 12 :Ce b The phosphor is expressed by the formula: ##EQU1## Note that the same raw material powders as those of Sample 1 were weighed out in the amounts shown in Table 1 for each sample, and phosphors were produced under the same conditions as those of Sample 1, and their luminescence and temperature characteristics were evaluated. The results are shown in Table 1. As described above, novel phosphors with good luminescence and temperature characteristics can be realized in many samples. Note that the solid solution amount of Ba, a [mol], is preferably 1.0 or less, more preferably 0.6 or less, and even more preferably 0.4 or less.

[0037] Furthermore, phosphors synthesized using raw materials mixed by liquid-phase mixing, such as the citric acid sol-gel method, the hexamine method, and the urea method, also exhibited comparable luminescence characteristics. While various methods can be used to manufacture the phosphor according to this embodiment, for example, when using the solid-phase method, the use of high-purity powder raw materials makes it difficult for impurities to be introduced, and raw material mixing can be completed in a short time (approximately 10 minutes). Furthermore, when using the liquid-phase method, mixing at the atomic level is possible, making it possible to create phosphors with different compositions at the 1 / 100 mol level.

[0038] Fig. 3 shows the relationship between the amount of Ce solid solution (b) and the dominant wavelength λd when the amount of Ba solid solution (a) is constant. Fig. 4 shows the relationship between the amount of Ba solid solution (a) and the dominant wavelength λd when the amount of Ce solid solution (b) is constant. The open marks in Figs. 3 and 4 indicate samples whose dominant wavelength λd does not satisfy the range of 567.4 nm≦λd≦570.6 nm.

[0039] As shown in Figure 3, when the amount of Ba solid solution is constant, the dominant wavelength shifts to the longer wavelength side as the amount of Ce solid solution increases. On the other hand, as shown in Figure 4, when the amount of Ce solid solution is constant, the dominant wavelength shifts to the shorter wavelength side as the amount of Ba solid solution increases. In other words, to keep the dominant wavelength within the desired range, it is necessary to increase the amount of Ce solid solution as the amount of Ba solid solution increases.

[0040] FIG. 5 is a graph showing the relationship between the amount of Ce solid solution (b) and the lattice size S when the amount of Ba solid solution (a) is constant. FIG. 6 is a graph showing the relationship between the amount of Ba solid solution (a) and the lattice size S when the amount of Ce solid solution (b) is constant. Here, the lattice size S is the ratio of the amount of Ba solid solution (b) to the amount of Ce solid solution (b) when the general formula is Ba a Y 3-a-b Al 5-a Si a O 12 :Ce bThe lattice size S is the measured value of the phosphor expressed as follows. The lattice size S was calculated using XRD measurement data analysis software (PDXL-II) manufactured by Rigaku Corporation. The open marks in Figures 5 and 6 indicate samples whose dominant wavelength λd does not satisfy the range of 567.4 nm ≦ λd ≦ 570.6 nm. The lattice size S measured for each sample is shown in Table 2.

[0041] [Table 2]

[0042] As shown in Figure 5, when the amount of solute Ba is constant, the lattice size S tends to increase as the amount of solute Ce increases. On the other hand, as shown in Figure 6, when the amount of solute Ce is constant, the lattice size S tends to decrease as the amount of solute Ba increases. However, the effects of the amounts of solute Ba and solute Ce on the lattice size S differ. Specifically, the results of the approximation line in Figure 5 show that a 1 mol increase in the amount of solute Ce increases the lattice size S by 0.036 Å. On the other hand, the results of the approximation curve in Figure 6 show that a 1 mol increase in the amount of solute Ba decreases the lattice size S by 0.003 Å.

[0043] Therefore, the lattice size that results in the dominant wavelength of a yellow phosphor suitable for a white light source in a vehicle headlight was calculated as a pseudo-corrected corrected lattice size S'. The corrected lattice size S' was assumed to be S' = S + 0.036b - 0.003a, where S is the measured lattice size, a (mol) is the amount of solid solution of Ba, and b (mol) is the amount of solid solution of Ce. The corrected lattice size S' for each sample is shown in Table 2.

[0044] Fig. 7 shows the relationship between the lattice size S and the dominant wavelength λd when the amount of Ba in solid solution is constant. Fig. 8 shows the relationship between the corrected lattice size S' and the dominant wavelength λd. As shown in Fig. 7, as the lattice size S increases, the dominant wavelength λd shifts to the longer wavelength side.

[0045] Then, by plotting the relationship between the corrected lattice size S' that reflects the amount of Ba solid solution (a) and the amount of Ce solid solution (b) and the dominant wavelength λd for each sample, it can be seen that the corrected lattice size S' must satisfy 12.0113 ≦ S' ≦ 12.0153 when the dominant wavelength λd is in the range of 567.4 nm ≦ λd ≦ 570.6 nm, as shown in Figure 8. In other words, when the amount of Ba solid solution (a) and the amount of Ce solid solution (b) satisfy 12.0113 ≦ S + 0.036b - 0.003a ≦ 12.0153, the general formula for emitting light at the desired dominant wavelength is Ba. a Y 3-a-b Al 5-a Si a O 12 :Ce b It was found that a yellow phosphor represented by the formula:

[0046] [Light-emitting module] FIG. 9 is a schematic diagram of a light-emitting module according to the present embodiment. Light-emitting module 10 according to the present embodiment includes a mounting substrate 12, an LED 14 as a light-emitting element mounted on mounting substrate 12, and an optical wavelength conversion layer 16 in which a phosphor is dispersed in a resin. LED 14 emits blue light with a peak wavelength in the range of 430 to 480 nm. Optical wavelength conversion layer 16 includes a silicone resin that is transparent to visible light and in which the yellow phosphor according to the present embodiment is dispersed. Optical wavelength conversion layer 16 contains 0.1 to 30 vol% of the yellow phosphor and has a thickness t of 0.01 to 5 mm. The thickness may be in the range of 0.1 to 2 mm. The volume concentration of the yellow phosphor may be 10 vol% or less. The yellow phosphor may have a mean volume diameter (MV) of 1 to 30 μm.

[0047] This light-emitting module 10 includes an optical wavelength conversion layer 16 that is excited by blue light emitted by the LED 14 and emits yellow light. The optical wavelength conversion layer 16 contains the above-mentioned phosphor. This light-emitting module 10 emits light with a chromaticity in the range surrounded by chromaticity coordinates (cx, cy) = (0.311, 0.339), (0.313, 0.342), (0.331, 0.354), (0.331, 0.338), (0.319, 0.315), and (0.311, 0.309). This allows for the realization of a light-emitting module 10 that achieves a desired luminous efficiency while emitting light with a chromaticity in the range suitable for the headlamp.

[0048] Alternatively, the optical wavelength conversion layer 16 may be a ceramic plate having a thickness of 0.01 to 2.0 mm. This ceramic plate is transparent to visible light and is obtained by pressure-molding a phosphor and then vacuum- or pressure-firing it. The light-emitting module 10 may be configured such that the LED 14 and the optical wavelength conversion layer 16 are bonded at room temperature.

[0049] A specific method for manufacturing the ceramic plate is to place 5 g of the phosphor (λd=569.0 nm) according to Sample 9, 0.5 wt% TEOS (tetraethoxysilane), and 50 g of φ1 mm alumina balls in a 100 ml plastic pot, rotate for 24 hours, then transfer to a fluororesin-coated aluminum tray and heat-dry. The dried product is then crushed using a nylon 50 mesh pass, weighed out in 1 g portions, placed in a φ20 mm mold, and molded at 10 MPa. The mixture is then further molded at 98 MPa using CIP (cold isostatic pressing).

[0050] The molded product is placed in a vacuum furnace at 1 x 10 -3The sintered body was then heated at 196 MPa, 1750°C, and 24 hours, and then further heated by HIP (Hot Isostatic Pressing) at 196 MPa, 1650°C, and 2 hours to obtain a transparent sintered body (transparent ceramic plate) with a thickness of approximately 1 mm. The transparent sintered body was polished to a desired thickness using mirror polishing, and each piece was cut into 1 mm square pieces. These pieces were then bonded to a blue LED chip at room temperature to produce a light-emitting module according to this embodiment that emits white light.

[0051] [Sintered body containing phosphor powder] A sintered body, which is an example of a fluorescent member containing a phosphor powder, which is a powder of the above-mentioned phosphor, will be described in more detail. The sintered body may be produced using various known sintering techniques. For example, the phosphor powder may be filled into a mold, molded, and then subjected to CIP and HIP or the like to produce a sintered body.

[0052] The sintered body may contain various materials in addition to the phosphor powder as needed. For example, it may contain a thermally conductive powder, which is a powder of a material with a thermal conductivity higher than that of the phosphor. This material may be, for example, aluminum nitride (AlN), a dielectric with a thermal conductivity of about 170 W / mK, or aluminum oxide (Al2O3), with a thermal conductivity of about 20 W / mK. By including a thermally conductive powder in addition to the phosphor powder, the sintered body can dissipate heat generated when the sintered body emits light more quickly than if the sintered body did not contain a thermally conductive powder. According to this embodiment, the heat dissipation properties of the sintered body can be improved, so that even when the sintered body is mounted in a high-brightness LED, temperature rise during light emission can be suppressed, and degradation of light-emitting performance at high temperatures can be suppressed.

[0053] Furthermore, the volume ratio of the phosphor powder to the thermally conductive powder contained in the sintered body is preferably 90:10 to 60:40. By having the volume ratio of the thermally conductive powder be 10 vol% or more and the volume ratio of the phosphor powder be 90 vol% or less, the heat dissipation properties of the sintered body can be further improved. By having the volume ratio of the thermally conductive powder be 40 vol% or less and the volume ratio of the phosphor powder be 60 vol% or more, the light absorption rate (e.g., blue light with a peak wavelength of 450 nm) and the light transmittance (e.g., yellow light with a wavelength of 550 to 600 nm) of the sintered body can be increased. In this specification, the volume ratio refers to the volume ratio relative to the total volume of the phosphor powder and the thermally conductive powder contained in a fluorescent member such as a sintered body.

[0054] The shape of the sintered body is not particularly limited and can be processed into various shapes, but the shape of the sintered body may be, for example, a plate shape having a predetermined thickness. Also, the shape of the sintered body may be, for example, a shape having a predetermined thickness used as an optical wavelength conversion layer shown in FIG.

[0055] The thickness of the sintered body is not particularly limited, but is preferably 120 to 300 μm (0.12 to 0.30 mm). When the thickness of the sintered body is 120 μm or more, the mechanical strength of the sintered body can be increased. This makes the sintered body less likely to break and easier to handle. Furthermore, when the thickness of the sintered body is 300 μm or less, leakage of light irradiated onto the sintered body from the LED through the side surfaces of the sintered body is suppressed, making it possible to increase the effective luminous flux of the sintered body.

[0056] The sintered body may transmit light of various wavelengths, for example, light with a wavelength of 550 to 600 nm. Furthermore, the transmittance of the sintered body for light (for example, light with a wavelength of 550 to 600 nm) may be 70% or more. The sintered body (more specifically, the phosphor contained in the sintered body) may absorb light of various wavelengths, for example, blue light with a peak wavelength of 450 nm. Furthermore, the absorptance of the sintered body for blue light may be, for example, 78 to 88%. This allows a light source that emits white light suitable for a desired application (for example, a headlamp) to be realized by combining a light source that emits blue light (for example, an LED) with a fluorescent member. For example, by combining a blue LED with a fluorescent material, it is possible to realize a light source that emits white light with a chromaticity in the range enclosed by the chromaticity coordinates (cx, cy) = (0.311, 0.339), (0.313, 0.342), (0.331, 0.354), (0.331, 0.338), (0.319, 0.315), and (0.311, 0.309).

[0057] The sintered body containing the phosphor powder will be described in more detail below using examples.

[0058] (Sample 36) The phosphor used in sample 36 was Ba 0.04 Y 2.91 Al 4.96 Si 0.04 O 12 :Ce 3+ 0.05 First, powder raw materials of BaCO3 (99.9%), Y2O3 (99.9%), α-Al2O3 (99.99%), SiO2, and CeO2 (99.99%) were prepared. Then, each powder raw material was weighed out to achieve the following molar ratios: Ba = 0.04, Y = 2.91, Al = 4.96, Si = 0.04, and Ce = 0.05.

[0059] BaF2 (99%) was weighed as a flux, accounting for 5 wt% of the total weight of the powder raw materials. This BaF2 was then combined with the weighed powder raw materials and mixed uniformly in a mortar to obtain a mixed powder. The mixed powder was then placed in an alumina crucible (SSA-S B1, manufactured by Nikkato Corporation) and heated to 1550°C for 4 hours in a reducing atmosphere (H2:N2 = 5 / 95 (vol ratio)) to sinter the mixed powder, obtaining a phosphor. The phosphor was then cooled to room temperature and crushed in a mortar to obtain a phosphor powder with a particle size of 1 to 30 μm.

[0060] The obtained phosphor powder and AlN powder (99.9%) were weighed out so that the volume ratio was 90:10. Next, the phosphor powder and AlN powder were mixed and pulverized using a ball mill so that the particle size of these powders was 3 μm or less.

[0061] The powder obtained by mixing and pulverization was filled into a φ20 mm mold and molded at a molding pressure of 10 MPa to obtain a primary compact. Next, the primary compact was compression molded at a molding pressure of 98 MPa using CIP to obtain a secondary compact. Next, a heating furnace was used to compress the primary compact to obtain a 1×10 -3 The secondary compact was heated at 1650°C for 24 hours in a nitrogen atmosphere of 196 MPa. The heated secondary compact was then heated by HIP at 196 MPa and 1550°C for 24 hours to obtain a sintered compact. The obtained sintered compact was then ground and polished using sandpaper to a thickness of 100 μm, and cut into 1 mm square pieces to prepare plate-shaped sintered compact samples.

[0062] The thermal conductivity of the samples was measured by a steady-state method using a thermal conductivity meter. The standard value for thermal conductivity was set at 30 W / mK, and if the measured value was equal to or greater than this standard value, the sample was evaluated as having good thermal conductivity.

[0063] The transmittance of the sample was measured using a spectrophotometer (Hitachi). The wavelength of the excitation light was 460 nm, and the measurement light was yellow light with a wavelength of 600 nm. When the transmittance of the yellow light was 70% or more, the sample was evaluated as having good transmittance.

[0064] The absorbance of the sample was measured using an integrating sphere. The excitation light was blue light with a wavelength of 460 nm. A sample was evaluated as having good absorbance when the absorbance of blue light was 78% to 88%.

[0065] In addition, the effective luminous flux of the sample was measured using an illuminometer. Specifically, a plate-shaped sample was mounted on an LED chip that emits 460 nm excitation light, and the LED chip was made to emit excitation light. Measurements were taken just above and on the sides of the sample, and the effective luminous flux was calculated. If the amount of light leaking from the sides of the sample was 10% or less, the sample's effective luminous flux was evaluated as good.

[0066] Furthermore, if the sample was not broken when handled with tweezers, the sample was evaluated as having good handleability.

[0067] Furthermore, when the thermal conductivity, transmittance, absorptance, ease of handling, and effective luminous flux of a sample were all evaluated as good, the overall evaluation of the sample was determined to be good.

[0068] The preparation conditions and evaluation results for each sample are summarized in Table 3. In Table 3, the thermal conductivity was evaluated as ○ if the measured value was 30 W / mK or higher, and × if the measured value was less than 30 W / mK. The transmittance was evaluated as ○ if the measured value was 70% or higher, and × if the measured value was less than 70%. The absorbance was evaluated as ○ if the measured value was 78% to 88%, and × if the measured value was not 78% to 88%. The handleability was evaluated as ○ if the sample was not damaged when handled with tweezers, and × if the sample was damaged. The effective luminous flux was evaluated as ○ if the amount of light leaking from the side of the sample during measurement was 10% or less, and × if the amount of light leaking from the side of the sample was more than 10%. The overall evaluation was evaluated as ○ if the sample was good, and × if the sample was not good.

[0069] [Table 3]

[0070] (Samples 37-41) For Samples 37 to 41, sintered samples were prepared in the same manner as Sample 36, except that the thickness of the sample was changed to 120, 180, 240, 300, or 360 μm.

[0071] (Samples 42-59) For Samples 42 to 59, sintered body samples were prepared in the same manner as Sample 36, except that the volume ratio of the phosphor powder to the AlN powder and the sample thickness were changed to the values ​​shown in Table 3. Specifically, the volume ratio of the phosphor powder to the AlN powder was set to 70:30, 60:40, or 50:50, and for each volume ratio, the sintered body samples were prepared with a sample thickness of 100, 120, 180, 240, 300, or 360 μm.

[0072] (Sample 60) In the preparation of Sample 60, the mixed powder was heated and sintered in the same manner as Sample 36, and the obtained phosphor was pulverized in a mortar to obtain phosphor powder. This phosphor powder was pulverized using a ball mill without being mixed with AlN powder.

[0073] Next, the phosphor powder pulverized using a ball mill was filled into a φ20 mm mold and compacted under a compacting pressure of 10 MPa to obtain a primary compact. Subsequently, a sintered body sample was prepared in the same manner as Sample 36.

[0074] (Sample 61) A sintered sample of Sample 61 was prepared in the same manner as Sample 44, except that Al2O3 powder was mixed with the phosphor powder instead of AlN powder, i.e., the volume ratio of the phosphor powder to the thermal conductive powder was 70:30, and the sample thickness was 180 μm.

[0075] The method for preparing the samples has been described above, and the evaluation results will now be described.

[0076] The thermal conductivity of samples 36 to 59 containing AlN powder all exceeded the standard value and was good. Furthermore, samples with an AlN powder volume fraction of 10 to 40 vol% and a thickness of 120 to 300 μm were good in all evaluation items: thermal conductivity, transmittance, absorptance, handleability, and effective luminous flux. The evaluation results are explained in more detail below.

[0077] Sample 60, which does not contain thermally conductive powder, received good ratings for transmittance, absorptance, ease of handling, and effective luminous flux, but did not receive a good rating for thermal conductivity. Sample 61 contains Al2O3 powder, which has a higher thermal conductivity than the phosphor. Therefore, although the thermal conductivity of Sample 61 was higher than that of Sample 60, it did not receive a good rating.

[0078] Compared to the sample related to sample 61, sample 44 has the thermally conductive powder changed from Al2O3 powder to AlN powder. Since the thermal conductivity of AlN is higher than that of Al2O3, the thermal conductivity of sample 44 is higher than that of sample 61, and is a good value.

[0079] Furthermore, all of Samples 36 to 59 containing AlN powder had good thermal conductivity (>30 W / mK). Therefore, it was found that the thermal conductivity of the sample was good if the volume fraction of AlN powder was at least 10 vol% or more.

[0080] Furthermore, among samples 42 to 59, in which the volume fraction of AlN powder was 30 vol% or more, the transmittance was less than 70% in samples with a thickness of 360 μm, but the transmittance was good in samples with a thickness of 300 μm or less.

[0081] Furthermore, among samples 54 to 59, which have an AlN powder volume fraction of 50 vol%, samples with thicknesses of 100 to 300 μm had an absorptivity of less than 78%, but samples with a thickness of 360 μm showed good absorptivity results. Furthermore, samples with thicknesses of 100 to 300 μm were able to suppress light leakage from the side surfaces of the samples, resulting in good results for effective luminous flux.

[0082] Furthermore, samples with a thickness of less than 120 μm had low mechanical strength and did not provide good results in terms of handleability, but samples with a thickness of 120 μm or more did not break even when handled with tweezers, and provided good results in terms of handleability.

[0083] [Light-emitting module] (Sample 62) 9 was fabricated as Sample 62. Specifically, a sintered body containing phosphor powder and AlN powder fabricated under the same conditions as Sample 43 was used as an optical wavelength conversion layer, and the optical wavelength conversion layer was room-temperature bonded to a sapphire mounting substrate so that the optical wavelength conversion layer covered the light-emitting surface of a blue LED (peak wavelength: 460 nm), thereby fabricating a white light-emitting module.

[0084] In sample 62, the chromaticity of the emitted color of the light-emitting module was within the chromaticity range suitable for headlamps, with chromaticity (cx, cy) = (0.32, 0.33). Therefore, in this example, by mounting a fluorescent member according to one embodiment of the present invention on a blue LED, it can be said that a white LED with excellent high-temperature characteristics suitable for specific applications (such as vehicle headlights) was fabricated.

[0085] Although the present invention has been described above with reference to the above-mentioned embodiments, the present invention is not limited to the above-mentioned embodiments, and suitable combinations and substitutions of the configurations of the embodiments are also included in the present invention. Furthermore, it is possible for those skilled in the art to appropriately rearrange the combinations and processing orders in the embodiments, or to make various design changes and other modifications to the embodiments, based on their knowledge, and such modified embodiments are also included in the scope of the present invention.

[0086] In the above embodiment, a sintered body is described as an example of the fluorescent member containing phosphor powder and thermally conductive powder. However, the fluorescent member is not limited to this, and may be, for example, a resin in which phosphor powder and thermally conductive powder are dispersed. [Industrial Applicability]

[0087] The present invention can be used for phosphors. [Explanation of symbols]

[0088] 10 light emitting module, 12 mounting substrate, 14 LED, 16 light wavelength conversion layer.

Claims

1. The crystal structure is garnet-type, The general formula is Ba ａ Y ３－ａ－ｂ Al ５－ａ Si ａ O １２ : Ce ｂ (wherein, when the lattice size of the crystal structure is S [Å], the amount of solid solution of Ba is a [mol], and the amount of solid solution of Ce is b [mol], a and b are values ​​within a range that satisfies 12.0113≦S+0.036b−0.003a≦12.0153).

2. 2. The phosphor according to claim 1, which is excited by blue light having a peak wavelength in the range of 430 to 480 nm and emits yellow light having a dominant wavelength in the range of 567 to 572 nm.

3. 3. The phosphor according to claim 1, wherein the amount of solid solution of Ba, a [mol], is 1.0 or less.

4. 4. The phosphor according to claim 1, wherein the volume average particle size is 1 to 30 μm.

5. A phosphor powder which is a powder of the phosphor according to any one of claims 1 to 4; a thermally conductive powder containing a compound having a thermal conductivity higher than that of the phosphor; A fluorescent member comprising:

6. 6. The fluorescent member according to claim 5, wherein a volume ratio of the phosphor powder to the thermally conductive powder is in the range of 90:10 to 60:

40.

7. the phosphor powder absorbs light having a peak wavelength of 450 nm; The thickness of the fluorescent member is 0.12 to 0.30 mm, 7. The fluorescent member according to claim 5, wherein the transmittance of the fluorescent member for light having a wavelength of 550 to 600 nm is 70% or more.

8. the phosphor powder absorbs blue light having a peak wavelength of 450 nm; 8. The fluorescent member according to claim 5, wherein the absorptance of the blue light by the fluorescent member is 78 to 88%.

9. A fluorescent member, A resin that is transparent to visible light, The phosphor according to claim 1 , which is encapsulated in the resin; the phosphor is contained in the resin at 0.1 to 30 vol %; The fluorescent member has a thickness of 0.01 to 5 mm.

10. an LED that emits blue light with a peak wavelength in the range of 430 to 480 nm; an optical wavelength conversion layer that is excited by the blue light emitted by the LED and emits yellow light; The light wavelength conversion layer includes the fluorescent member according to any one of claims 5 to 9, A light-emitting module characterized in that the emitted color obtained by mixing the blue light and the yellow light has a chromaticity in the range surrounded by chromaticity coordinates (cx, cy) = (0.311, 0.339), (0.313, 0.342), (0.331, 0.354), (0.331, 0.338), (0.319, 0.315), and (0.311, 0.309).

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