Optical wavelength conversion member and light-emitting device

Abstract

An optical wavelength conversion member and a light-emitting device including the optical wavelength conversion member. The optical wavelength conversion member (9) is formed of a ceramic sintered body having a fluorescent phase containing fluorescent crystal grains as a main component and a translucent phase containing translucent crystal grains as a main component. Crystal grains of the fluorescent phase have a composition represented by formula A.sub.3B.sub.5O.sub.12:Ce, where the element A is selected from Sc, Y, and lanthanoids (except for Ce), and the element B is selected from Al and Ga. In the optical wavelength conversion member (9), 0.3<a<34 and 300 m<y<1,050 m are satisfied, wherein a represents the area ratio of the translucent phase to the fluorescent phase in a cross section of the optical wavelength conversion member (9), and y represents the interfacial length of the fluorescent phase.

Claims

1. An optical wavelength conversion member comprising a ceramic sintered body having a fluorescent phase containing fluorescent crystal grains as a main component and a translucent phase containing translucent crystal grains as a main component, wherein the crystal grains of the fluorescent phase have a composition represented by formula A.sub.3B.sub.5O.sub.12:Ce, and each of the element A and the element B is at least one element selected from the following element groups: A: Sc, Y, and lanthanoids (except for Ce), and B: Al and Ga; and the following relations are satisfied: 0.3<a<34 and 300 m<y<1,050 m, wherein a represents the ratio of the area of the translucent phase to the area of the fluorescent phase in a cross section of the optical wavelength conversion member, and y represents the interfacial length of the fluorescent phase.

2. An optical wavelength conversion member according to claim 1, wherein the following relation is satisfied: 1.1<x<2.1, wherein x represents the ratio of the mean grain size r1 of crystal grains of the translucent phase to the mean grain size r2 of crystal grains of the fluorescent phase; the crystal grains of the translucent phase have a mean grain size r1 of 0.2 m to 6 m; and the crystal grains of the fluorescent phase have a mean grain size r2 of 0.1 m to 4 m.

3. An optical wavelength conversion member according to claim 1, wherein the crystal grains of the translucent phase have a composition of Al.sub.2O.sub.3.

4. An optical wavelength conversion member according to claim 1, wherein the ceramic sintered body contains a compound represented by formula A.sub.3B.sub.5O.sub.12:Ce in an amount of 3 vol. % to 70 vol. %.

5. An optical wavelength conversion member according to claim 1, wherein the Ce content of the compound represented by formula A.sub.3B.sub.5O.sub.12:Ce is 0.1 mol % to 1.0 mol % relative to the element A of the compound.

6. A light-emitting device comprising an optical wavelength conversion member as recited in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 Cross-sectional view of a light-emitting device in a thickness direction, the light-emitting device including an optical wavelength conversion member according to an embodiment.

(2) FIG. 2 Explanatory view showing a production process for the optical wavelength conversion member according to the embodiment.

(3) FIG. 3 Schematic view showing an SEM image of a cross section of the optical wavelength conversion member according to the embodiment; specifically, schematic view showing an SEM image of an unetched cross-sectional surface.

(4) FIG. 4 Schematic view showing an SEM image of a cross section of the optical wavelength conversion member according to the embodiment; specifically, schematic view showing an SEM image of an etched cross-sectional surface.

(5) FIG. 5 Explanatory view showing a method of determining color unevenness.

MODES FOR CARRYING OUT THE INVENTION

(6) Next will be described an optical wavelength conversion member and a light-emitting device according to an embodiment of the present disclosure.

1. Embodiment

(7) [1-1. Light-Emitting Device]

(8) Now will be described an optical wavelength conversion member and a light-emitting device according to the present embodiment.

(9) As illustrated in FIG. 1, a light-emitting device 1 of the present embodiment includes a box-shaped ceramic package (container) 3 formed of, for example, alumina; a light-emitting element 5 (e.g., LD) disposed in the interior of the container 3; and a plate-like optical wavelength conversion member 9 disposed so as to cover an opening 7 of the container 3.

(10) In the light-emitting device 1, light emitted from the light-emitting element 5 transmits through the translucent optical wavelength conversion member 9, and the wavelength of a portion of the emitted light is converted in the interior of the optical wavelength conversion member 9. Thus, the optical wavelength conversion member 9 emits fluorescence having a wavelength different from that of light emitted from the light-emitting element 5.

(11) For example, the optical wavelength conversion member 9 converts the wavelength of blue light emitted from an LD, whereby the optical wavelength conversion member 9 as a whole emits white light to the outside (e.g., upward in FIG. 1).

(12) [1-2. Optical Wavelength Conversion Member]

(13) The optical wavelength conversion member 9 will now be described.

(14) The optical wavelength conversion member 9 of the present embodiment is formed of a ceramic sintered body having a fluorescent phase containing fluorescent crystal grains (i.e., fluorescent phase grains) as a main component and a translucent phase containing translucent crystal grains (i.e., translucent phase grains) as a main component.

(15) In the optical wavelength conversion member 9, the fluorescent phase grains have a composition represented by formula A.sub.3B.sub.5O.sub.12:Ce, and each of the element A and the element B is at least one element selected from the following element groups:

(16) A: Sc, Y, and lanthanoids (except for Ce), and

(17) B: Al and Ga.

(18) A and B of the aforementioned chemical formula A.sub.3B.sub.5O.sub.12:Ce correspond to elements (different elements) forming a substance represented by formula A.sub.3B.sub.5O.sub.12:Ce wherein O is oxygen and Ce is cerium.

(19) In the optical wavelength conversion member 9, the following relations are satisfied: 0.3<a<34 and 300 m<y<1,050 m wherein a represents the ratio of the area of the translucent phase to the area of the fluorescent phase in a cross section of the optical wavelength conversion member 9, and y represents the interfacial length of the fluorescent phase in a predetermined region.

(20) The predetermined region corresponds to a unit area of 500 m.sup.2, and the interfacial length y is the total of interfacial lengths corresponding to the perimeter lengths of fluorescent phases in the unit area.

(21) In addition, the following relation is satisfied: 1.1<x<2.1, wherein x represents the ratio of the mean grain size r1 of the translucent phase grains to the mean grain size r2 of the fluorescent phase grains; the translucent phase grains have a mean grain size r1 of 0.2 m to 6 m; and the fluorescent phase grains have a mean grain size r2 of 0.1 m to 4 m.

(22) In the optical wavelength conversion member 9, the ceramic sintered body contains a compound represented by formula A.sub.3B.sub.5O.sub.12:Ce in an amount of 3 vol. % to 70 vol. %.

(23) The Ce content of the compound represented by formula A.sub.3B.sub.5O.sub.12:Ce is 0.1 mol % to 1.0 mol % relative to the element A of the compound.

(24) The translucent phase grains have, for example, a composition of Al.sub.2O.sub.3.

(25) [1-2. Production Method for Optical Wavelength Conversion Member]

(26) A schematic production process for the optical wavelength conversion member 9 will now be briefly described with reference to FIG. 2.

(27) Firstly, powder materials for the optical wavelength conversion member 9 (i.e., ceramic sintered body) were weighed so as to satisfy the aforementioned embodiment (i.e., the powder materials were prepared).

(28) Subsequently, an organic solvent and a dispersant were added to the prepared powder materials, and these materials were ground and mixed in a ball mill, to thereby prepare a slurry.

(29) Subsequently, the slurry was dried and granulated.

(30) The resultant granular product was then press-formed into a compact.

(31) The compact was then fired at a specific temperature for a specific period of time, to thereby prepare a ceramic sintered body.

(32) The ceramic sintered body may be produced by any process instead of the aforementioned press-forming process. For example, the ceramic sintered body may be produced by a process involving formation of a sheet from the slurry, and firing of the sheet.

(33) [1-3. Effects]

(34) The effects of the present embodiment will now be described.

(35) (1) In the present embodiment, the ceramic sintered body basically has a garnet structure represented by A.sub.3B.sub.5O.sub.12:Ce containing at least one element selected from the aforementioned element groups. This property can achieve effective conversion of blue light into visible light.

(36) Particularly in the present embodiment, the area ratio a of the translucent phase to the fluorescent phase in a cross section of the optical wavelength conversion member 9 satisfies the following relation 0.3<a<34, and the interfacial length y of the fluorescent phase satisfies the following relation 300 m<y<1,050 m. Thus, when the optical wavelength conversion member 9 is irradiated with light emitted from the light-emitting element 5, high illuminance and high fluorescence intensity are achieved, and color unevenness is reduced.

(37) (2) In the present embodiment, the grain size ratio x (i.e., the ratio of the mean grain size r1 of the translucent phase grains to the mean grain size r2 of the fluorescent phase grains) satisfies the relation 1.1<x<2.1; the crystal grains of the translucent phase have a mean grain size r1 of 0.2 m to 6 m; and the crystal grains of the fluorescent phase have a mean grain size r2 of 0.1 m to 4 m.

(38) This characteristic feature achieves further high illuminance and fluorescence intensity and reduced color unevenness.

(39) (3) In the present embodiment, the ceramic sintered body contains a compound represented by formula A.sub.3B.sub.5O.sub.12:Ce in an amount of 3 vol. % to 70 vol. %.

(40) This characteristic feature achieves further high illuminance and fluorescence intensity and reduced color unevenness.

(41) (4) In the present embodiment, the Ce content of the compound represented by formula A.sub.3B.sub.5O.sub.12:Ce is 0.1 mol % to 1.0 mol % relative to the element A of the compound.

(42) This characteristic feature achieves further high illuminance and fluorescence intensity and reduced color unevenness.

(43) (5) The light (i.e., fluorescence) having a wavelength converted with the light-emitting device 1 (specifically, the optical wavelength conversion member 9) of the present embodiment exhibits high fluorescence intensity. The light exhibits reduced color unevenness; i.e., high color uniformity.

2. Examples

(44) Specific examples of the aforementioned embodiment will next be described.

(45) There were prepared ceramic sintered body samples (Nos. 1 to 30) shown below in Table 1; i.e., samples of optical wavelength conversion members of Examples 1 to 5.

(46) Samples Nos. 3 to 7 and 11 to 30 fall within the scope of the present disclosure, and samples Nos. 1, 2, and 8 to 10 fall outside the scope of the present disclosure (Comparative Examples).

(47) [2-1. Sample Evaluation Method]

(48) Now will be described methods of evaluating the samples.

(49) <Relative Density>

(50) The density of each ceramic sintered body sample was measured by the Archimedes method, and the measured density was converted into a relative density.

(51) <Open Porosity>

(52) The open porosity of each ceramic sintered body sample was measured by the method specified by JIS R1634.

(53) <Area Ratio>

(54) Each ceramic sintered body sample was sectioned, and the cross-sectional surface was subjected to mirror polishing. The polished surface was observed under a scanning electron microscope (SEM) at a magnification of 5,000, to thereby prepare an SEM image. FIG. 3 is a schematic view of an example of an SEM image. In FIG. 3, off-white bright portions correspond to fluorescent phases, and dark (black) portions correspond to translucent phases.

(55) In a 500 m.sup.2 region of the SEM image, the area ST of translucent phases and the area SK of fluorescent phases were measured. The area ratio a of the area ST of translucent phases to the area SK of fluorescent phases (i.e., ST/SK) was determined through calculation.

(56) The aforementioned area was determined through processing of the SEM image with image analysis software (e.g., Winloof). In an SEM image (5,000), the area may be measured in a specific visual field region, and then the specific visual field region may be converted into a 500 m.sup.2 region for determination of the area ratio a. For determination of the below-described interfacial length, the specific visual field region may be converted into a 500 m.sup.2 region in the same manner as described above.

(57) <Mean Crystal Grain Size>

(58) Each ceramic sintered body sample was sectioned, and the cross-sectional surface was subjected to mirror polishing and subsequent thermal etching at 1,350 C. The etched surface was subjected to SEM observation, to thereby prepare 2,500 images (i.e., SEM images) at five positions of the ceramic sintered body. FIG. 4 is a schematic view of an example of SEM image. In FIG. 4, bright portions correspond to fluorescent phase grains, and dark portions correspond to translucent phase grains.

(59) Five lines were drawn in a 20 m square region of the SEM image at each of the aforementioned positions, and the intercept method was used to determine the mean crystal grain sizes (i.e., mean grain sizes) of fluorescent phase grains and translucent phase grains. Thus, the mean grain size r2 of fluorescent phase grains and the mean grain size r1 of translucent phase grains were determined in all the five regions.

(60) <Grain Size Ratio>

(61) The grain size ratio x was calculated from the mean grain size r2 of fluorescent phase grains and the mean grain size r1 of translucent phase grains by use of the following formula (1).
Grain size ratio x=(the mean grain size r1 of translucent phase grains)/(the mean grain size r2 of fluorescent phase grains)(1)
<Interfacial Length>

(62) In the 5,000 SEM image used for determination of the area ratio, the interfacial length of each fluorescent phase was determined by use of the aforementioned image analysis software (e.g., Winloof) in each of the five regions. Thus, the interfacial length per fluorescent phase unit was determined. In a region including a plurality of fluorescent phases, the interfacial lengths of the fluorescent phases were summed. Thus, the interfacial lengths of all the fluorescent phases were determined in each region, and the interfacial lengths were summed (i.e., the total interfacial length was determined) in each region.

(63) Each of the five regions has an area of 500 m.sup.2. The total interfacial lengths were determined in the five regions and then averaged. The average value was defined as the interfacial length y.

(64) FIG. 3 illustrates an example of the interfacial length; i.e., the interfacial length per fluorescent phase unit. In FIG. 3, the length of a white annular line surrounding one fluorescent phase (i.e., one off-white bright portion) corresponds to the interfacial length per fluorescent phase unit.

(65) <Illuminance>

(66) Illuminance was measured by means of an illuminometer. Specifically, each sample was processed into a shape of 13 mm13 mm0.2 mm (thickness). Blue LD light (wavelength: 465 nm) was focused to a width of 0.5 mm by means of a lens, and the processed sample was irradiated with the focused light. A spectroradiometer (CL-500A, manufactured by KONICA MINOLTA, INC.) was used to determine the illuminance of the light transmitting through the surface of the sample opposite the surface irradiated with the focused light.

(67) Illuminance (%) was evaluated by a value relative to that (taken as 100) of a YAG:Ce single-crystal body.

(68) <Color Unevenness>

(69) Color unevenness (i.e., variation in color) was evaluated through determination of a variation in chromaticity by means of an illuminometer.

(70) Specifically, each sample was processed into a shape of 13 mm13 mm0.2 mm (thickness). Blue LD light (wavelength: 465 nm) was focused to a width of 0.5 mm by means of a lens, and the processed sample was irradiated with the focused light. A spectroradiometer (CL-500A, manufactured by KONICA MINOLTA, INC.) was used to determine the chromaticity of the light transmitting through the surface of the sample opposite the surface irradiated with the focused light.

(71) As illustrated in FIG. 5, a 9 mm square center portion of the surface of each sample (i.e., sample surface) was divided into nine regions (at intervals of 3 mm), and the light irradiation was performed on each region. A variation (X) in chromaticity (in X-direction) of the region was evaluated. As used herein, the term variation (X) refers to the maximum deviation of chromaticity (in X-direction). A variation X of less than 0.03 is preferred.

(72) The term chromaticity as used herein refers to a chromaticity indicated by the CIE-XYZ color system established by the International Commission on Illumination (CIE) in 1931. Specifically, the chromaticity is indicated by the xy chromaticity diagram (so-called CIE chromaticity diagram), wherein three primary colors of light are digitized and represented in an xy coordinate space.

(73) <Fluorescence Intensity>

(74) Each sample was processed into a shape of 13 mm13 mm0.2 mm (thickness). Blue LD light (wavelength: 465 nm) was focused to a width of 0.5 mm by means of a lens, and the processed sample was irradiated with the focused light. The light transmitting through the sample was focused by means of a lens, and the emission intensity (i.e., fluorescence intensity) was measured by means of a power sensor. The sample was irradiated with the light at a power density of 40 W/mm.sup.2.

(75) Fluorescence intensity (%) was evaluated by a value relative to that (taken as 100) of a YAG:Ce single-crystal body.

(76) [2-2. Production Method for Sample and Evaluation Results]

(77) Next will be described a production method for each sample, and the results of evaluation of the sample.

Example 1

(78) Ceramic sintered body samples Nos. 1 to 9 (i.e., optical wavelength conversion members) were prepared under the conditions shown in Table 1.

(79) Specifically, for preparation of each ceramic sintered body sample, Al.sub.2O.sub.3 powder (mean particle size: 0.2 m), Y.sub.2O.sub.3 powder (mean particle size: 1.2 m), Gd.sub.2O.sub.3 powder (mean particle size: 1.5 m), and CeO.sub.2 powder (mean particle size: 1.5 m) were weighed as shown in Table 1.

(80) The A.sub.3B.sub.5O.sub.12:Ce content was fixed to 30 vol. % relative to the entire ceramic sintered body. The Ce content was fixed to 0.3 mol % relative to the element A.

(81) These powders were added to a ball mill together with ethanol, and these materials were ground and mixed for 4 to 48 hours. The resultant slurry was dried and granulated, and the resultant granular product was press-formed into a compact. The compact was fired in air at 1,500 to 1,800 C. for 2 to 10 hours.

(82) Specifically, in samples Nos. 1 and 2, the grinding was performed for more than 30 hours, and the firing was performed at 1,500 C. for two to five hours.

(83) In samples Nos. 3 to 7, the grinding was performed for 16 hours, and the firing was performed at 1,500 C. to 1,750 C. for 10 hours.

(84) In samples Nos. 8 and 9, the grinding was performed for 16 hours and 4 hours, respectively, and the firing was performed at 1,800 C. for 10 hours.

(85) The samples of Example 1 can be prepared under the aforementioned conditions (different grinding times and firing conditions). For example, the longer the grinding time, the smaller the crystal grain size. When the firing temperature is elevated, crystal grains are grown; i.e., an increase in grain size. Thus, these conditions probably affect the interfacial length.

(86) Subsequently, each ceramic sintered body sample produced in the aforementioned manner was evaluated by the aforementioned evaluation methods. The results are shown in Table 1.

(87) As shown in Table 1, samples Nos. 3 to 7 (area ratio a: 0.3<a<34, interfacial length y of fluorescent phase: 300 m<y<1,050 m) exhibited good results; i.e., high fluorescence intensity, high illuminance, and reduced color unevenness.

(88) In contrast, samples Nos. 1 and 2 (interfacial length y: more than 1,050 m) exhibited low transmittance and low fluorescence intensity and illuminance. Samples Nos. 8 and 9 (interfacial length y: less than 300 m) exhibited increased color unevenness due to very high transmittance of blue light.

(89) Although not shown in Table 1, all the samples exhibited a relative density of 99% or more. Similarly, the samples of Examples 2 to 4 exhibited a relative density of 99% or more.

Example 2

(90) Ceramic sintered body samples Nos. 10 to 19 were prepared under the conditions shown in Table 1.

(91) In Example 2, samples were prepared basically in the same manner as in Example 1.

(92) However, the grinding was performed for 16 hours, the firing was performed at 1,600 C. for 10 hours, and the A.sub.3B.sub.5O.sub.12:Ce content was fixed to 1 vol. % to 80 vol. % relative to the entire ceramic sintered body.

(93) Each ceramic sintered body sample produced in the aforementioned manner was evaluated by the aforementioned evaluation methods. The results are shown in Table 1.

(94) As shown in Table 1, samples Nos. 11 to 18 (A.sub.3B.sub.5O.sub.12:Ce content: 3 vol. % to 70 vol. %) exhibited good results; i.e., high emission intensity and reduced color unevenness.

(95) In contrast, sample No. 10 (A.sub.3B.sub.5O.sub.12:Ce content: 1 vol. %) exhibited low fluorescence intensity due to insufficient fluorescence. Sample No. 19 (A.sub.3B.sub.5O.sub.12:Ce content: 80 vol. %) exhibited a considerable increase in temperature due to reduced thermal conduction, and low emission intensity due to temperature quenching.

Example 3

(96) Ceramic sintered body samples Nos. 20 to 26 were prepared under the conditions shown in Table 1.

(97) In Example 3, samples were prepared basically in the same manner as in Example 1.

(98) However, the grinding time and the firing conditions were the same as those in Example 2. The A.sub.3B.sub.5O.sub.12:Ce content was fixed to 30 vol. % relative to the entire ceramic sintered body, and the Ce content was adjusted to 0.05 mol. % to 2.0 mol. %.

(99) Each ceramic sintered body sample produced in the aforementioned manner was evaluated by the aforementioned evaluation methods. The results are shown in Table 1.

(100) As shown in Table 1, samples Nos. 21 to 25 (Ce content: 0.1 mol. % to 1 mol. %) exhibited good results; i.e., high emission intensity, high illuminance, and reduced color unevenness.

(101) In contrast, sample No. 20 (Ce content: less than 0.1 mol. %) exhibited low fluorescence intensity due to a small amount of emission center ion (i.e., insufficient fluorescence). Sample No. 26 (Ce content: more than 1 mol. %) exhibited low fluorescence intensity due to concentration quenching caused by excess Ce.

Example 4

(102) Ceramic sintered body samples Nos. 27 to 30 were prepared under the conditions shown in Table 1.

(103) In Example 4, samples were prepared basically in the same manner as in Example 1.

(104) However, Y.sub.2O.sub.3 powder was used in combination with at least one of Lu.sub.2O.sub.3 powder (mean particle size: 1.3 m), Yb.sub.2O.sub.3 powder (mean particle size: 1.5 m), and Ga.sub.2O.sub.3 powder (mean particle size: 1.3 m). During mixing of the raw materials, the proportions of the raw materials were varied so that specific A.sub.3B.sub.5O.sub.12:Ce was synthesized. The grinding time and the firing conditions were the same as those in Example 2.

(105) Each ceramic sintered body sample produced in the aforementioned manner was evaluated by the aforementioned evaluation methods. The results are shown in Table 1.

(106) As shown in Table 1, all the ceramic sintered body samples (Nos. 27 to 30) exhibited good results in terms of illuminance, fluorescence intensity, and color unevenness.

(107) TABLE-US-00001 TABLE 1 Area ratio Translucent A.sub.3B.sub.5O.sub.12:Ce (translucent phase mean content Ce content Open porosity phase/fluorescent grain size No. A B (vol %) (mol %) (%) phase) (m) Example 1 1 Y, Gd Al 30 0.3 0.4 2.33 0.11 2 Y, Gd Al 30 0.3 0.02 2.38 0.24 3 Y, Gd Al 30 0.3 0.02 2.32 0.32 4 Y, Gd Al 30 0.3 0.01 2.31 0.98 5 Y, Gd Al 30 0.3 0 2.28 1.44 6 Y, Gd Al 30 0.3 0.01 2.44 1.87 7 Y, Gd Al 30 0.3 0.02 2.39 3.6 8 Y, Gd Al 30 0.3 0.02 2.39 6.2 9 Y, Gd Al 30 0.3 0.2 2.32 9 Example 2 10 Y, Gd Al 1 0.3 0.01 81.64 1.1 11 Y, Gd Al 3 0.3 0.02 32.67 1.08 12 Y, Gd Al 5 0.3 0.02 17.98 1.07 13 Y, Gd Al 10 0.3 0.01 8.79 1.02 14 Y, Gd Al 30 0.3 0.02 2.31 0.98 15 Y, Gd Al 40 0.3 0.01 1.49 0.95 16 Y, Gd Al 50 0.3 0.02 1.00 0.9 17 Y, Gd Al 60 0.3 0 0.66 0.88 18 Y, Gd Al 70 0.3 0 0.43 0.87 19 Y, Gd Al 80 0.3 0.01 0.25 0.85 Example 3 20 Y, Gd Al 30 0.05 0.01 2.32 0.6 21 Y, Gd Al 30 0.1 0.01 2.37 0.92 22 Y, Gd Al 30 0.3 0.01 2.31 0.98 23 Y, Gd Al 30 0.5 0 2.28 0.97 24 Y, Gd Al 30 0.7 0.01 2.36 0.97 25 Y, Gd Al 30 1 0.02 2.37 0.97 26 Y, Gd Al 30 2 0.02 2.35 0.97 Example 4 27 Lu Al 30 0.3 0.01 2.37 1.36 28 Lu Al, Ga 30 0.3 0 2.26 1.41 29 Yb Al 30 0.3 0.03 2.39 1.51 30 Yb Al, Ga 30 0.3 0 2.27 1.46 Grain size A.sub.3B.sub.5O.sub.12:Ce ratio of A.sub.3B.sub.5O.sub.12:Ce mean grain translucent interfacial Color Fluorescence size phase/fluorescent length Illuminance unevenness intensity No. (m) phase (m) (%) (X) (%) Example 1 1 0.1 1.1 1070 78 0.0006 83 2 0.22 1.09 1056.07 80 0.0007 85 3 0.24 1.33 823.41 101 0.0008 100 4 0.58 1.69 802.19 120 0.001 110 5 0.91 1.58 749.00 125 0.0016 114 6 1.09 1.72 616.00 130 0.0019 125 7 2.2 1.64 484.00 124 0.0024 120 8 2.9 2.14 294.56 95 0.0032 95 9 4.1 2.20 275.00 93 0.0045 89 Example 2 10 0.51 2.16 817.04 78 0.004 80.0 11 0.52 2.08 814.92 100 0.0026 100.0 12 0.52 2.06 814.92 113 0.0022 103.0 13 0.55 1.85 808.56 118 0.0015 105.0 14 0.58 1.69 802.19 120 0.001 110 15 0.62 1.53 793.71 110 0.00095 118.0 16 0.67 1.34 783.10 108 0.00088 120.0 17 0.72 1.22 772.50 106 0.00085 124.0 18 0.75 1.16 766.13 103 0.00084 128.0 19 0.78 1.09 759.77 84 0.0008 130.0 Example 3 20 0.58 1.03 812.80 80 0.0024 82 21 0.54 1.70 810.68 105 0.0012 100 22 0.58 1.69 802.19 120 0.001 110 23 0.57 1.70 804.32 123 0.0011 115 24 0.56 1.73 806.44 110 0.0015 105 25 0.55 1.76 808.56 104 0.0016 101 26 0.88 1.10 806.44 90 0.0014 92 Example 4 27 0.92 1.48 762.00 130 0.0015 120 28 0.94 1.50 753.00 124 0.0012 115 29 1.02 1.48 744.00 120 0.0011 114 30 1.05 1.39 780.00 140 0.0012 105

4. Other Embodiments

(108) Needless to say, the present disclosure is not limited to the aforementioned embodiment, but may be implemented in various other forms without departing from the scope of the present invention.

(109) (1) For example, the aforementioned embodiment employs an air firing process for the preparation of a sample.

(110) However, a hot pressing process, a vacuum firing process, a reducing-atmosphere firing process, an HIP process, or any combination of these processes may be used for the preparation of a sample having the same properties as those described in the embodiment.

(111) (2) The aforementioned optical wavelength conversion member or light-emitting device can be used for various applications, including fluorescent bodies, optical wavelength conversion apparatuses, head lamps, lighting apparatuses, and optical apparatuses (e.g., projectors).

(112) (3) No particular limitation is imposed on the light-emitting element used for the light-emitting device. The light-emitting element may be any well known one, such as LED or LD.

(113) (4) In the aforementioned embodiment, the function of a single component may be shared by a plurality of components, or a single component may exert the functions of a plurality of components. Some of the components in the aforementioned embodiment may be omitted. At least some of the components in the aforementioned embodiment may be, for example, added to or replaced with components in another embodiment.

(114) Embodiments of the present disclosure encompass any form included in technical ideas specified by the appended claims.

DESCRIPTION OF REFERENCE NUMERALS

(115) 1: light-emitting device; 5: light-emitting element; and 9: optical wavelength conversion member