Sialon-based oxynitride phosphor and production method thereof

a technology of oxynitride phosphor and sialon, which is applied in the direction of luminescent compositions, discharge tubes, lighting and heating apparatus, etc., can solve the problems of not being suited light is slightly blue-tinged, and not being suitable for use as phosphor powders, etc., to achieve excellent miscibility with resin, good miscibility with resin, and little scattering

Inactive Publication Date: 2009-11-19
UBE IND LTD
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Benefits of technology

[0012]The present inventors have studied the correlation between the mixing and firing method for a raw material powder containing silicon nitride and various substances as a lithium source, a calcium source, a rare earth metal source and an aluminum source, which are used for the production of a sialon-based oxynitride phosphor, and the dispersibility and fluorescent property of the produced powder. As a result, it has been found that: when instead of mixing the raw material powder all at once, a part of the raw material powder is previously mixed and fired and to the obtained first raw material powder, the remaining raw material powder is again added, mixed and fired, a sialon-based oxynitride phosphor assured of less fusion bonding or aggregation and high dispersibility, with the difference between the secondary particle size and the primary particle size being small, can be produced; a monodisperse sialon-based oxynitride phosphor can be obtained by selecting the combination of various raw materials and the firing conditions; and only a sialon-based oxynitride powder having specific particle diameter, particle size distribution and dispersibility can be utilized as a phosphor giving uniform fluorescence and high emission intensity. The present invention has been accomplished based on these findings.
[0078]According to the present invention, a sialon-based oxynitride phosphor extremely reduced in the aggregation of primary particles and excellent in miscibility with a resin and dispersibility in a resin is obtained. This phosphor excellent in miscibility with a resin and dispersibility in a resin has characteristic features such as little scattering of incident light, uniform fluorescent property, no color unevenness, stable color tone and high emission intensity. According to the production method of a sialon-based oxynitride phosphor of the present invention, the method has a first step where a mixed powder obtained by previously adding at least one kind of a metal compound selected from a nitride, an oxynitride, an oxide or a precursor substance becoming an oxide upon thermal decomposition, of a metal M (M is at least one metal selected from the group consisting of Li, Ca, Mg, Ba, Sr, Y and a lanthanide metal excluding La, Ce, Pr, Eu, Dy, Er, Th and Yb) solid-dissolved in an α-sialon, and a nitride, an oxynitride, an oxide or a precursor substance becoming an oxide upon thermal decomposition, of a lanthanide metal Ln (Ln is at least one lanthanide metal selected from the group consisting of Ce, Pr, Eu, Dy, Er, Th and Yb) substituting a part or all of the metal element M to work as a luminescence center, to a silicon nitride powder is fired at 1,400 to 1,800° C. in a nitrogen-containing inert gas atmosphere to obtain a first raw material powder, so that the above-described a sialon-based oxynitride phosphor having high dispersibility can be obtained in a high yield.
[0079]Furthermore, a lighting device such as a white LED fabricated by combining the sialon-based oxynitride phosphor of the present invention with blue LED or violet LED is uniform and stable in the brightness and color tone and is excellent in view of performance, because high-quality light free of color unevenness is obtained. As for the advantage in view of production, by virtue of use of the sialon-based oxynitride phosphor of the present invention, the fluctuation of quality within and among the lots of the white LED product is small and the yield of the product is high.

Problems solved by technology

However, the fluorescence wavelength of Ce-doped YAG is in the vicinity of 530 nm and when this fluorescence color and light of blue LED are mixed to produce white light, the light is slightly blue-tinged and good white color cannot be obtained.
Even when a grinding treatment is applied, only an aggregate of massive particles each resulting from firm fusion bonding of primary particles is obtained and this is not suited for use as a phosphor powder.
However, in this method, the yield of the sialon powder having a particle diameter of 2 to 20 μm is less than 55 wt %.
Moreover, the amount of Eu remaining in the particle after acid treatment is small, and excessive Eu needs to be added for obtaining a high-brightness phosphor powder.
Furthermore, there is a problem that as the particle becomes finer, the brightness of the phosphor decreases.

Method used

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  • Sialon-based oxynitride phosphor and production method thereof
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  • Sialon-based oxynitride phosphor and production method thereof

Examples

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example 1

[0179]Silicon diimide (Si(NH)2) obtained by reacting silicon tetrachloride with ammonia at a temperature lower than room temperature was decomposed under heating at 700 to 1,200° C. to obtain silicon nitrogen imide (Si2N2NH) and / or amorphous silicon nitride powder. The metal impurity content of the silicon nitrogen imide (Si2N2NH) and / or amorphous silicon nitride powder was 10 ppm or less. A blend obtained by blending a compound(s) as a silicon nitride source(s) selected from nitrogen-containing silane compounds (silicon diimide (Si(NH)2) and silicon nitrogen imide (Si2N2NH)), amorphous silicon nitride and crystalline silicon nitride to give a chemical composition shown in Table 1 was used as the silicon nitride raw material. A europium oxide (Eu2O3) powder, a lithium carbonate (Li2CO3) powder and a calcium carbonate (CaCO3) powder were weighed and added to the silicon nitride raw material to give a chemical composition of Si9.25Eu0.15Ca0.62Li0.10O0.89N12.33 after firing, and these ...

example 2

[0186]An α-sialon-based oxynitride phosphor was obtained by repeating the same operation as in Example 1, except that the blending ratio of the compound(s) working as a silicon nitride source(s) selected from nitrogen-containing silane compounds (silicon diimide (Si(NH)2) and silicon nitrogen imide (Si2N2NH)), amorphous silicon nitride and crystalline silicon nitride and the firing conditions in the first and second steps were slightly changed. The conditions in the synthesis of the α-sialon-based oxynitride phosphor comprising first and second steps are shown in Table 1, and the powder properties and fluorescent properties of the obtained oxynitride phosphor are shown in Table 2.

[0187]FIG. 2 illustrates the emission spectrum at an excitation wavelength of 450 nm of the α-sialon-based oxynitride phosphor obtained in Example 2 together with the emission spectra of the α-sialon-based oxynitride phosphor obtained in Comparative Example 4 and a commercially available YAG:Ce-based fluore...

examples 3 to 15

[0188]Similarly to Example 1, those obtained by blending a compound(s) working as a silicon nitride source(s) selected from nitrogen-containing silane compounds (silicon diimide (Si(NH)2) and silicon nitrogen imide (Si2N2NH)), amorphous silicon nitride and crystalline silicon nitride to give a chemical composition shown in Table 1 were used as the silicon nitride raw material. A europium oxide (Eu2O3) powder and a lithium oxide precursor powder were weighed and added to the silicon nitride raw material to give a chemical composition of Si12−(m+n)EuyLix′O0.5x′+1.5y−δN16−4(m+n) / 3 (wherein 0≦δ≦0.5y), and these were mixed by a vibration mill under the conditions shown in Table 1 in a nitrogen atmosphere.

[0189]The mixed powder was filled in a silicon nitride-made crucible, the crucible was set in an electric furnace of resistance heating system, and the furnace was heated in a nitrogen gas atmosphere by a temperature-rising schedule of holding the furnace at from temperature to 1,150° C....

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Abstract

The present invention relates to an oxynitride phosphor comprising an α-sialon as the main component, which is represented by the general formula: MxSi12−(m+n)Al(m+n)OnN16−n:Lny (wherein 0.3≦x+y<1.5, 0<y<0.7, 0.3≦m<4.5, 0<n<2.25, and assuming that the atomic valence of the metal M is a and the atomic valence of the lanthanide metal Ln is b, m=ax+by) and in which the aggregation index, A1=D50 / DBET≦3.0 or the aggregation index A2=D50 / Dparticle≦3.0; and a production method and usage of the phosphor.The phosphor of the present invention has less aggregation and a narrow particle size distribution, and therefore is easy to uniformly mix with a resin or the like, and a high-brightness white LED can be easily obtained.D50 [μm]: The median diameter in the grain size distribution curve.DBET [μm]: The equivalent-sphere diameter calculated on the basis of a BET specific surface area.Dparticle [μm]: The primary particle diameter measured by the image analysis of a scanning electron micrograph.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2006-185134, filed on Jul. 5, 2006, the contents of which are incorporated herein by reference.TECHNICAL FIELD[0002]The present invention relates to an optical functional material having a function of converting a part of irradiation light into light at a wavelength different from that of the irradiation light and at the same time, mixing the converted light with the unconverted irradiation light to cause conversion into light differing in the color, and a production method thereof. More specifically, the present invention relates to a rare earth metal element-activated sialon-based oxynitride phosphor used for a white light-emitting diode (white LED) using a blue light-emitting diode (blue LED) as a light source. The present invention also relates to a production method of a sialon-based oxynitride phosphor for the above-described white...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): F21V9/16C09K11/77C09K11/08C09K11/64C09K11/80H01J1/63H01L33/50
CPCC04B35/597H01L33/502C04B35/62675C04B35/62685C04B2235/3203C04B2235/3208C04B2235/3217C04B2235/3224C04B2235/3852C04B2235/3865C04B2235/3873C04B2235/3895C04B2235/44C04B2235/442C04B2235/5296C04B2235/5409C04B2235/5436C04B2235/5481C04B2235/80C09K11/0883C09K11/7734H01J2211/42C04B35/6261H01L2924/181H01L2224/48091H01L2224/48247H01L2224/45144C09K11/77348H01L2924/00012H01L2924/00014H01L2924/00H01L33/50
Inventor YAMAO, TAKESHIYAMADA, TETSUOSAKATA, SHIN-ICHI
Owner UBE IND LTD
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