Process for production of phosphors

Patent metadata

Field	Value
Publication number	US-9580649-B2
Application number	US-201314414233-A
Country	US
Kind code	B2
Filing date	Jun 14, 2013
Priority date	Jul 13, 2012
Publication date	Feb 28, 2017
Grant date	Feb 28, 2017

Abstract

The present invention relates to a process for the preparation of a europium-doped alkaline-earth metal siliconitride or silicooxynitride having increased emission efficiency. The present invention furthermore relates to europium-doped alkaline-earth metal siliconitrides or silicooxynitrides which are obtainable by the preparation process according to the invention, and to the use of the europium-doped alkaline-earth metal siliconitrides or silicooxynitrides according to the invention as conversion phosphors. The present invention furthermore also relates to a light-emitting device which comprises a europium-doped alkaline-earth metal siliconitride or silicooxynitride according to the invention.

First claim

The invention claimed is:

1. Process for increasing the radiation-induced emission efficiency and/or for shifting the emission wavelength of a europium-doped alkaline-earth metal siliconitride or of a europium-doped alkaline-earth metal silicooxynitride, comprising the steps:
(a) preparation of a mixture of a europium-doped alkaline-earth metal siliconitride or a europium-doped alkaline-earth metal silicooxynitride and an alkaline-earth metal nitride, where the alkaline-earth metal of the europium-doped alkaline-earth metal siliconitride or of the europium-doped alkaline-earth metal silicooxynitride and of the alkaline-earth metal nitride may be identical or different; and
(b) calcination of the mixture under non-oxidising conditions.

2. Process according to claim 1 , in which the weight ratio of europium-doped alkaline-earth metal siliconitride or silicooxynitride to the alkaline-earth metal nitride in the mixture is in the range from 2:1 to 20:1.

3. Process according to claim 1 , in which the alkaline-earth metal in the alkaline-earth metal nitride is different from the alkaline-earth metal in the alkaline-earth metal siliconitride or silicooxynitride.

4. Process according to claim 1 , in which the europium-doped alkaline-earth metal siliconitride or silicooxynitride employed is prepared by a step (a′), where step (a′) comprises the calcination of a mixture comprising a europium source, a silicon source and an alkaline-earth metal nitride under non-oxidising conditions and precedes step (a) of the process according to claim 1 .

5. Process according to claim 1 , in which the europium-doped alkaline-earth metal siliconitride or silicooxynitride is a compound of the general formula (I) or (II),
EA d Eu c E e N f O x .m SiO 2 .n Si 3 N 4   (I)

in which the following applies to the symbols and indices used:
EA is at least one alkaline-earth metal;
E is Si;
0.80≦d≦1.995;
0.005≦c≦0.2;
4.0≦e≦6.00;
5.00≦f≦8.70;
0≦x≦3.00;
0≦m≦2.50;
0≦n≦0.50;
where the following relationship furthermore applies to the indices:
2 d+ 2 c+ 4 e= 3 f+ 2 x;
Ba 1−a−b−c Sr a Ca b Eu c Si 7 N 10 .m SiO 2 .n Si 3 N 4   (II)

where the indices used have the following meanings:
0≦a≦1;
0≦b≦1;
0.01≦c≦0.2;
0≦m≦2.50;
0≦n≦0.50; and
a+b+c≦1.

6. Process according to claim 5 where the index “c” used for Formula II has the following meaning: 0.02≦c≦0.1.

7. Process according to claim 1 , in which the europium-doped alkaline-earth metal siliconitride or silicooxynitride is a compound of the formula (Ia) or (Ib),
Ba 2−a−b−c+1.5z Sr a Ca b Eu c Si 5 N 8−2/3x+z O x .m SiO 2 .n Si 3 N 4   (Ia)

where the indices used have the following meanings:
0≦a≦2;
0≦b≦2;
0.01≦c≦0.2;
0≦x≦1;
0≦z≦3.0;
0≦m≦2.50;
0≦n≦0.50;
and a+b+c≦2+1.5z;
Ba 2−a−b−c−0.5x+1.5z Sr a Ca b Eu c Si 5 N 8−x+z O x .m SiO 2 .n Si 3 N 4   (Ib)

where the indices used have the following meanings:
0≦a≦2;
0≦b≦2;
0.01≦c≦0.2;
0≦x≦1;
0≦z≦3.0;
0≦m≦2.50;
0≦n≦0.50.

8. Process according to claim 7 where the indices c, x and z used for Formula Ia have the following meanings: 0.02≦c≦0.1; 0≦x≦0.6; and 0≦z≦1.0 the indices c, x and z used for Formulae Ib have the following meanings: 0.02≦c≦0.1; 0≦x≦0.6; and 0≦z≦1.0.

9. Process according to claim 8 where the index “z” used for Formulae Ia and Ib has the following meaning: z=0.

10. Process according to claim 1 , in which the alkaline-earth metal nitride is selected from the group consisting of calcium nitride, strontium nitride, barium nitride and mixtures thereof.

11. Process according to claim 1 , in which the calcination is carried out at a temperature in the range from 1200 to 2000° C.

12. Process according to claim 1 , in which the non-oxidising conditions are produced by a reducing atmosphere.

13. Process according to claim 12 , in which the reducing atmosphere comprises hydrogen.

14. Process for the preparation of a post-treated europium-doped alkaline-earth metal siliconitride or europium-doped alkaline-earth metal silicooxynitride comprising the following steps:
(i) synthesis of a europium-doped alkaline-earth metal siliconitride or a europium-doped alkaline-earth metal silicooxynitride;
(ii) calcination of a mixture comprising the europium-doped alkaline-earth metal siliconitride or europium-doped alkaline-earth metal silicooxynitride obtained in step (i) and an alkaline-earth metal nitride under non-oxidising conditions.

15. Process according to claim 14 , characterised in that the synthesis of the europium-doped alkaline-earth metal siliconitride or of the europium-doped alkaline-earth metal silicooxynitride in step (i) is carried out by calcination of a mixture comprising a europium source, a silicon source and an alkaline-earth metal nitride under non-oxidising conditions.

16. Process according to claim 14 , in which the weight ratio of the europium-doped alkaline-earth metal siliconitride or silicooxynitride obtained in step (i) to the alkaline-earth metal nitride in the mixture in step (ii) is in the range from 2:1 to 20:1.

17. Process according to claim 14 , in which the post-treated europium-doped alkaline-earth metal siliconitride or silicooxynitride is a compound of the general formula (I) or (II),
EA d Eu c E e N f O x .m SiO 2 .n Si 3 N 4   (I)

in which the following applies to the symbols and indices used:
EA is at least one alkaline-earth metal;
E is Si;
0.80≦d≦1.995;
0.005≦c≦0.2;
4.0≦e≦6.00;
5.00≦f≦8.70;
0≦x≦3.00;
0≦m≦2.50;
0≦n≦0.50;
where the following relationship furthermore applies to the indices:
2 d+ 2 c+ 4 e= 3 f+ 2 x;
Ba 1−a−b−c Sr a Ca b Eu c Si 7 N 10 .m SiO 2 .n Si 3 N 4   (II)

where the indices used have the following meanings:
0≦a≦1;
0≦b≦1;
0.01≦c≦0.2;
0≦m≦2.50;
0≦n≦0.50; and
a+b+c≦1.

18. Process according to claim 14 , in which the post-treated europium-doped alkaline-earth metal siliconitride or silicooxynitride is a compound of the formula (Ia) or (Ib),
Ba 2−a−b−c+1.5z Sr a Ca b Eu c Si 5 N 8−2/3x+z O x .m SiO 2 .n Si 3 N 4   (Ia)

where the indices used have the following meanings:
0≦a≦2;
0≦b≦2;
0.01≦c≦0.2;
0≦x≦1;
0≦z≦3.0;
0≦m≦2.50;
0≦n≦0.50;
and a+b+c≦2+1.5z;
Ba 2−a−b−c−0.5x+1.5z Sr a Ca b Eu c Si 5 N 8−x+z O x .m SiO 2 .n Si 3 N 4   (Ib)

where the indices used have the following meanings:
0≦a≦2;
0≦b≦2;
0.01≦c≦0.2;
0≦x≦1;
0≦z≦3.0;
0≦m≦2.50;
0≦n≦0.50.

19. Compound obtained by a process according to claim 5 .

20. Compound of the formula (Ia),
Ba 2−a−b−c+1.5z Sr a Ca b Eu c Si 5 N 8−2/3x+z O x .m SiO 2 .n Si 3 N 4   formula (Ia)

where the indices used have the following meanings:
0≦a≦2;
0≦b≦2;
0.01≦c≦0.2;
0<x≦1;
0≦z≦3.0;
0≦m≦2.50;
0≦n≦0.50;
and a+b+c≦2+1.5z.

21. Compound according to claim 20 , where the indices used for formula Ia have the following meanings:
0≦a≦2;
0≦b≦2;
0.02≦c≦0.1;
0.03≦x≦0.8;
0≦z≦1.0;
0≦m≦1.00;
n=0;
and a+b+c≦2+1.5z.

22. Compound according to claim 21 where the indices x, z and m used for formula I1 have the following meanings: 0≦x≦0.6; z=0 and m=0.

23. A method comprising converting LED emissions with a compound according to claim 19 .

24. Light-emitting device comprising a compound according to claim 19 .

Assignees

• Merck Patent Gmbh

Inventors

• Vosgroene Tim
• Winkler Holger
• Petry Ralf
• Benker Andreas
• Hampel Christof

Classifications

• C09K11/0883 Primary

  Arsenides; Nitrides; Phosphides · CPC title

• C09K11/77347 Primary

  Silicon Nitrides or Silicon Oxynitrides · CPC title

• H10H20/8512

  Wavelength conversion materials · CPC title

• C09K11/7734 Primary

  Aluminates · CPC title

• C09K11/59

  containing silicon · CPC title