Sialon phosphor particles and production method thereof

1. Sialon phosphor particles represented by the formula:

M x Ln y Si 12−(m+n) Al (m+n) O n N 16−n

(wherein M is at least one metal selected from the group consisting of Li, Ca, Mg and Y, Ln is a lanthanide metal containing at least Eu, and assuming that the valence of the metal M is a and the valence of the lanthanide metal Ln is b, m=ax+by, x is 0<x, y≦2.0, 0.3≦m<4.5, 1.0≦n<2.5 and 1.0≦m/n≦2.0), wherein, in a surface analysis by X-ray photoelectron spectroscopy, a ratio between a peak area of 3d 5/2 spectrum of Eu and a peak area of 2p spectrum of Si, obtained by acid-treating said sialon phosphor particles in which said ratio exceeds 0.5, is 0.5 or less.

2. A sialon phosphor powder comprising the sialon phosphor particles claimed in claim 1 , wherein said phosphor particles are aggregate particles and average particle diameter obtained by a laser diffraction/scattering particle size distribution measuring method is from 5 to 100 microns.

3. The sialon phosphor particles as claimed in claim 1 , wherein 1.25≦n<2.5.

4. The sialon phosphor particles as claimed in claim 2 , wherein 1.25≦n<2.5.

5. The sialon phosphor particles as claimed in claim 1 , wherein the ratio between the peak area of 3d 5/2 spectrum of Eu and the peak area of 2p spectrum of Si, obtained by acid-treating the sialon phosphor particles in which said ratio is from 2.32 to 2.68, is 0.5 or less.

6. The sialon phosphor particles as claimed in claim 2 , wherein the ratio between the peak area of 3d 5/2 spectrum of Eu and the peak area of 2p spectrum of Si, obtained by acid-treating the sialon phosphor particles in which said ratio is from 2.32 to 2.68, is 0.5 or less.

7. The sialon phosphor particles as claimed in claim 3 , wherein the ratio between the peak area of 3d 5/2 spectrum of Eu and the peak area of 2p spectrum of Si, obtained by acid-treating the sialon phosphor particles in which said ratio is from 2.32 to 2.68, is 0.5 or less.

8. The sialon phosphor particles as claimed in claim 4 , wherein the ratio between the peak area of 3d 5/2 spectrum of Eu and the peak area of 2p spectrum of Si, obtained by acid-treating the sialon phosphor particles in which said ratio is from 2.32 to 2.68, is 0.5 or less.

9. The sialon phosphor particles as claimed in claim 1 , wherein the ratio between the peak area of 3d 5/2 spectrum of Eu and the peak area of 2p spectrum of Si is 0.4 or less.

10. The sialon phosphor particles as claimed in claim 2 , wherein the ratio between the peak area of 3d 5/2 spectrum of Eu and the peak area of 2p spectrum of Si is 0.4 or less.

11. The sialon phosphor particles as claimed in claim 3 , wherein the ratio between the peak area of 3d 5/2 spectrum of Eu and the peak area of 2p spectrum of Si is 0.4 or less.

12. The sialon phosphor particles as claimed in claim 4 , wherein the ratio between the peak area of 3d 5/2 spectrum of Eu and the peak area of 2p spectrum of Si is 0.4 or less.

13. A method for producing the sialon phosphor particles claimed in claim 1 , comprising:

mixing (a) silicon nitride, (b) a substance which becomes an aluminum source and contains AlN, (c) an oxide of the metal M (wherein M is at least one metal selected from the group consisting of Li, Ca, Mg and Y) or a precursor substance which becomes an oxide upon thermal decomposition, and (d) an oxide of lanthanide metal Ln containing at least Eu, or a precursor substance which becomes an oxide upon thermal decomposition,

firing resulting mixed particles at 1,400 to 2,000° C. in a nitrogen-containing inert gas atmosphere, and

acid-treating obtained sialon particles with an acid solution selected from sulfuric acid, hydrochloric acid and nitric acid and having a concentration of 0.1 to 7 normal, thereby removing the glass layer on the surface.

14. The method as claimed in claim 13 , wherein concentration of the acid solution is from 1 to 3 normal.

15. The method as claimed in claim 13 , wherein the mixed powder is fired at 1,400 to 1,800° C. in a nitrogen gas atmosphere under 1 atm.

16. The method as claimed in claim 14 , wherein the mixed powder is fired at 1,400 to 1,800° C. in a nitrogen gas atmosphere under 1 atm.

17. A light-emitting device comprising:

a blue light-emitting element capable of emitting blue light having a peak at a wavelength of 430 to 475 nm, and

a phosphor layer containing the sialon phosphor particles claimed in claim 1 and capable of absorbing a part of the blue light and converting it into yellow light having a wavelength of 520 to 600 nm,

wherein white light can be emitted by the mixing of the blue light and the yellow light.

18. A light-emitting device comprising:

a blue light-emitting element capable of emitting blue light having a peak at a wavelength of 430 to 475 nm, and

a phosphor layer containing the sialon phosphor particles claimed in claim 2 and capable of absorbing a part of the blue light and converting it into yellow light having a wavelength of 520 to 600 nm,

wherein white light can be emitted by the mixing of the blue light and the yellow light.

19. A light-emitting device comprising:

a blue light-emitting element capable of emitting blue light having a peak at a wavelength of 430 to 475 nm, and

a phosphor layer containing the sialon phosphor particles claimed in claim 3 and capable of absorbing a part of the blue light and converting it into yellow light having a wavelength of 520 to 600 nm,

wherein white light can be emitted by the mixing of the blue light and the yellow light.

20. A light-emitting device comprising:

a violet light-emitting element capable of emitting violet light having a peak at a wavelength of 390 to 430 nm, and

a phosphor layer containing the sialon phosphor particles claimed in claim 1 and capable of absorbing a part of said violet light and converting it into yellow light having a wavelength of 520 to 600 nm,

wherein white light can be emitted by mixing said violet light and said yellow light.