Sialon-based oxynitride phosphor, process for its production, and use thereof

• US 20040155225A1
• Filed: 02/03/2004
• Published: 08/12/2004
• Est. Priority Date: 02/06/2003
• Status: Active Grant

• Current Assignee: UBE Corporation
• Original Assignee: UBE Industries Limited (UBE Corporation)
• Inventors: Sakata, Shin-ichi, Yamada, Tetsuo
• Granted Patent: US 7,074,346 B2
• Time in Patent Office: Days
• US Class Current: 252/301.4R
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3229 Cerium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3865 Aluminium nitrides
• CPC Class Codes: C04B 2235/3869 Aluminium oxynitrides, e.g. AlON, sialon
• CPC Class Codes: C04B 2235/3873 Silicon nitrides, e.g. silicon carbonitride, silicon oxynitride
• CPC Class Codes: C04B 2235/3878 Alpha silicon nitrides
• CPC Class Codes: C04B 2235/3895 Non-oxides with a defined oxygen content, e.g. SiOC, TiON
• CPC Class Codes: C04B 2235/483 Si-containing organic compounds, e.g. silicone resins, (poly)silanes, (poly)siloxanes or (poly)silazanes
• CPC Class Codes: C04B 2235/528 Spheres
• CPC Class Codes: C04B 2235/5409 expressed by specific surface values
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/5481 Monomodal
• CPC Class Codes: C04B 2235/608 Green bodies or pre-forms with well-defined density
• CPC Class Codes: C04B 2235/6584 at an oxygen percentage below that of air
• CPC Class Codes: C04B 2235/72 Products characterised by the absence or the low content of specific components, e.g. alkali metal free alumina ceramics
• CPC Class Codes: C04B 2235/721 Carbon content
• CPC Class Codes: C04B 2235/723 Oxygen content
• CPC Class Codes: C04B 2235/766 : Trigonal symmetry, e.g. alpha-Si3N4 or alpha-Sialon
• CPC Class Codes: C04B 35/597 : based on silicon oxynitride, e.g. SIALONS
• CPC Class Codes: C04B 35/6303 : Inorganic additives
• CPC Class Codes: C09K 11/0883 : Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/77068 : Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: C09K 11/77218 : Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: C09K 11/77348 : Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: C09K 11/77498 : Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: C09K 11/77748 : Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: H01L 2224/45144 : Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 : Arched
• CPC Class Codes: H01L 2224/48247 : connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 33/502 : Wavelength conversion materials

Abstract

An α-sialon-based oxynitride phosphor characterized in that the content of α-sialon represented by the general formula: M_xS_12−(m+n)Al_(m+n)O_nN_16−n:Ln_y (wherein M is at least one metal selected from among Li, Ca, Mg, Y or lanthanide metals excluding La and Ce, Ln is at least one lanthanide metal selected from among Ce, Pr and La or at least one lanthanide metal selected from among Eu, Dy, Er, Tb and Yb, 0.3≦x+y<1.5, 0<y<0.7, 0.3≦m<4.5, 0<n<2.25, and m=ax+by, where a is the valence of the metal M and b is the valence of the lanthanide metal Ln), wherein all or a portion of the metal M dissolved in the α-sialon is replaced with the lanthanide metal Ln as the luminescence center, is 75 wt % or greater when the lanthanide metal Ln is at least one lanthanide metal selected from among Ce, Pr and La and 90 wt % or greater when the lanthanide metal Ln is at least one lanthanide metal selected from among Eu, Dy, Er, Tb and Yb, and in that the content of metal impurities other than the metal M, lanthanide metal Ln, silicon, IIIA elements (aluminum, gallium), oxygen and nitrogen, is no greater than 0.01 wt %.

Claims

1. An α

-sialon-based oxynitride phosphor characterized in that the content of α

-sialon represented by the general formula;

M_xSi<sub>12−

(m+n)</sub>Al_(m+n)O_nN<sub>16−

n</sub>;

Ln_y

(wherein

M is at least one metal selected from among Li, Ca, Mg, Y or lanthanide metals excluding La and Ce,

Ln is at least one lanthanide metal selected from among Ce, Pr and La or at least one lanthanide metal selected from among Eu, Dy, Er, Tb and Yb,

0.3≦

x+y<

1.5,

0<

y<

0.7,

0.3≦

m<

4.5,

0<

n<

2.25, and

m=ax+by, where a is the valence of the metal M and b is the valence of the lanthanide metal Ln),

wherein all or a portion of the metal M dissolved in the α

-sialon is replaced with the lanthanide metal Ln as the luminescence center,

is 75 wt % or greater when the lanthanide metal Ln is at least one lanthanide metal selected from among Ce, Pr and La and 90 wt % or greater when the lanthanide metal Ln is at least one lanthanide metal selected from among Eu, Dy, Er, Tb and Yb,

and in that the content of metal impurities other than the metal M, lanthanide metal Ln, silicon, IIIA elements (aluminum, gallium), oxygen and nitrogen, is no greater than 0.01 wt %.

2. An α

-sialon-based oxynitride phosphor according to claim 1, wherein Ln is at least one lanthanide metal selected from among Ce, Pr and La, and the α

-sialon content is 90 wt % or greater as measured by powder X-ray diffraction, with the remainder consisting of β

-sialon and oxynitride glass.

3. An α

-sialon-based oxynitride phosphor according to claim 1, wherein Ln is at least one lanthanide metal selected from among Eu, Dy, Er, Tb and Yb, and the α

-sialon content is 95 wt % or greater as measured by powder X-ray diffraction, with the remainder consisting of β

-sialon and oxynitride glass.

4. An α

-sialon-based oxynitride phosphor according to claim 1, wherein the content of metal impurities other than the metal M, lanthanide metal Ln, silicon, IIIA elements (aluminum, gallium), oxygen and nitrogen, is no greater than 0.001 wt %.

5. An α

-sialon-based oxynitride phosphor according to claim 1, wherein the median size in the particle size distribution curve is no greater than 8 μ

m.

6. An α

-sialon-based oxynitride phosphor according to claim 1, wherein the 90% size in the particle size distribution curve is no greater than 25 μ

m.

15. A light emitting device comprising

a light emitting diode, and

a transparent medium comprising an oxynitride phosphor according to any one of claims 1 to 6 dispersed therein, and covering the surface of said light emitting diode.

16. A light emitting device according to claim 15, wherein said light emitting diode is a blue light emitting diode, and said luminescent device is a white light emitting device.

7. A process for producing an α

-sialon-based oxynitride phosphor, wherein a mixed powder comprising a nitrogen-containing silane compound and/or amorphous silicon nitride powder having the oxygen content adjusted to 1-5 wt %, AlN and/or Al powder, an oxide of a metal M or a precursor substance which is converted to an oxide of a metal M upon thermal decomposition, and an oxide of a lanthanide metal Ln or a precursor substance which is converted to an oxide of a lanthanide metal Ln upon thermal decomposition, in a combination such that the metal impurity content is no greater than 0.01 wt % as calculated on the basis of the product being represented by the general formula;

M_xSi<sub>12−

(m+n)</sub>Al_(m+n)O_nN<sub>16−

n</sub>;

Ln_y

(wherein M is at least one metal selected from among Li, Ca, Mg, Y or lanthanide metals excluding La and Ce, and

Ln is at least one lanthanide metal selected from among Ce, Pr and La or at least one lanthanide metal selected from among Eu, Dy, Er, Tb and Yb,

0.3≦

x+y<

1.5,

0<

y<

0.7,

0.3≦

m<

4.5,

0<

n<

2.25, and

m=ax+by, where a is the valence of the metal M and b is the valence of the lanthanide metal Ln), is fired at 1400-2000°

C. in a nitrogen-containing inert gas atmosphere.

9. A process for producing an α

-sialon-based oxynitride phosphor according to claim 7 or 8, wherein the specific surface area of the nitrogen-containing silane compound and/or amorphous silicon nitride powder is 80-600 m²/g.

10. A process for producing an α

-sialon-based oxynitride phosphor according to claim 7 or 8, characterized in that the content of metal impurities other than Li, Ca, Mg, Al, Si, Ga, Y and lanthanide metals in the nitrogen-containing silane compound and/or amorphous silicon nitride powder and the AlN and/or Al powder is no greater than 0.01 wt %, and the content of carbon is no greater than 0.3 wt %.

11. A process for producing an oxynitride phosphor composed mainly of α

-sialon according to claim 10, characterized in that the content of metal impurities other than Li, Ca, Mg, Al, Si, Ga, Y and lanthanide metals in the nitrogen-containing silane compound and/or amorphous silicon nitride powder and the AlN and/or Al powder is no greater than 0.001 wt %, and the content of carbon is no greater than 0.15 wt %.

12. A process for producing an oxynitride phosphor composed mainly of α

-sialon according to claim 7 or 8, characterized in that the firing is carried out at 1400-1800°

C. in a nitrogen-containing inert gas atmosphere at a pressure of 1 atmosphere.

13. A process for producing an oxynitride phosphor composed mainly of α

-sialon according to claim 7 or 8, characterized in that the firing is carried out in a temperature range of 1600-2000°

C. in a pressurized nitrogen gas atmosphere.

14. A process for producing an oxynitride phosphor composed mainly of α

-sialon according to claim 13, characterized in that the firing is carried out in a temperature range of 1600-1900°

C. in a pressurized nitrogen gas atmosphere.

8. A process for producing an α

-sialon-based oxynitride phosphor, wherein a mixture obtained by adding a pre-synthesized α

-sialon powder represented by the general formula;

M_xSi<sub>12−

(m+n)</sub>Al_(m+n)O_nN<sub>16−

n</sub> (wherein the definitions in the formula are the same as below) or the general formula;

M_xS<sub>12−

(m+n)</sub>Al_(m+n)O_nN<sub>16−

n</sub>;

Ln_y (wherein the definitions of M, Ln, x, y, m and n are the same as below) to a mixed powder comprising a nitrogen-containing silane compound and/or amorphous silicon nitride powder having the oxygen content adjusted to 1-5 wt %, AlN and/or Al powder, an oxide of a metal M or a precursor substance which is converted to an oxide of a metal M upon thermal decomposition, and an oxide of a lanthanide metal Ln or a precursor substance which is converted to an oxide of a lanthanide metal Ln upon thermal decomposition, in a combination such that the metal impurity content is no greater than 0.01 wt % as calculated on the basis of the product being represented by the general formula;

M_xSi<sub>12−

(m+n)</sub>Al_(m+n)O_nN<sub>16−

n</sub>;

Ln_y

(wherein M is at least one metal selected from among Li, Ca, Mg, Y or lanthanide metals excluding La and Ce, and

Ln is at least one lanthanide metal selected from among Ce, Pr and La or at least one lanthanide metal selected from among Eu, Dy, Er, Tb and Yb,

0.323 x+y<

1.5,

0<

y<

0.7,

0.3≦

m<

4.5,

0<

n<

2.25, and

m=ax+by, where a is the valence of the metal M and b is the valence of the lanthanide metal Ln), is fired at 1400-2000°

C. in a nitrogen-containing inert gas atmosphere.