Composite ceramic which comprises a conversion phosphor and a material having a negative coefficient of thermal expansion

Patent metadata

Field	Value
Publication number	US-9567519-B2
Application number	US-201314387876-A
Country	US
Kind code	B2
Filing date	Mar 2, 2013
Priority date	Mar 29, 2012
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

The present invention relates to a composite ceramic which comprises a conversion phosphor and a further material, characterized in that the further material has a negative coefficient of thermal expansion, and to a process for the preparation thereof. Furthermore, the present invention also relates to the use of the composite ceramic according to the invention as emission-converting material, preferably in a white light source, and to a light source, a lighting unit and a display device.

First claim

The invention claimed is:

1. Composite ceramic which comprises a conversion phosphor and a further material, wherein the further material has a negative coefficient of thermal expansion which is in the range from 1*10 −6 to 12*10 −6 K −1 in the case of a temperature change in the range from 20° C. to 200° C.

2. Composite ceramic according to claim 1 , in which the conversion phosphor is a Ce-, Eu- and/or Mn-containing material.

3. Composite ceramic according to claim 1 , in which the conversion phosphor is a Ce-containing material.

4. Composite ceramic according to claim 3 , in which the Ce-containing material is a Ce-containing garnet which has the formula E 3 G 2 (TO 4 ) 3 :Ce, where E is selected from the group consisting of Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu and mixtures thereof, and G and T are each selected, independently of one another, from the group consisting of Al, Sc, Ga and mixtures thereof, or G and T together stand for the combination Mg/Si or the combination Mg/Ge, where Mg and Si or Mg and Ge respectively are present in the same molar proportions.

5. Composite material according to claim 1 , in which the further material is a tungstate or molybdate.

6. Composite ceramic according to claim 1 , in which the molar ratio of the conversion phosphor to the further material is in the range from 1:0.5 to 10:1.

7. Process for the preparation of a composite ceramic according to claim 1 , which comprises:
a) providing a conversion phosphor;
b) providing a material having a negative coefficient of thermal expansion;
c) mixing of the two components provided in steps a) and b) to give a mixture; and
d) sintering of the mixture.

8. Process according to claim 7 wherein the sintering is carried out at a temperature in the range from ⅔ to ⅚ of the melting temperature of the material having a negative coefficient of thermal expansion.

9. Process for the preparation of a composite ceramic according to claim 1 , which comprises:
a′) coating of a conversion phosphor with an oxide of aluminium;
b′) mixing of the coated conversion phosphor obtained in step a′) with a W- or Mo-containing component to give a mixture; and
c′) sintering of the mixture obtained in step b′) at a temperature in the range from 1000 to 1600° C., to obtain a composite ceramic which comprises a conversion phosphor and an aluminium tungstate or aluminium molybdate material which has a negative coefficient of thermal expansion in the range from 1*10 −6 to 12*10 −6 K −1 in the case of a temperature change in the range from 20° C. to 200° C.

10. An emission-converting material comprising a composite ceramic according to claim 1 .

11. A light source comprising an emission-converting material according to claim 10 .

12. Light source which comprises a composite ceramic according to claim 1 and a primary light source.

13. Lighting unit which comprises at least one light source according to claim 12 .

14. Composite ceramic according to claim 1 , in which the conversion phosphor is a Ce-, Eu- and/or containing material, which comprises 0.1 to 5 atom-% of Ce, Eu and/or Mn, based on the total number of atoms at the lattice sites which are replaced by the Ce, Eu and/or Mn in the Ce-, Eu- and/or Mn-containing material.

15. Composite ceramic according to claim 1 , in which the conversion phosphor is a Ce-containing garnet.

16. Composite material according to claim 1 , in which the further material is a tungstate or molybdate, which is selected from the group consisting of Al 2 W 3 O 12 , Y 2 W 3 O 12 , YAlW 3 O 12 , ZrW 2 O 8 , Al 2 Mo 3 O 12 , Y 2 Mo 3 O 12 , YAlMo 3 O 12 , ZrMo 2 O 8 , Al 2 WMo 2 O 12 , Y 2 WMo 2 O 12 , YAlWMo 2 O 12 , ZrWMoO 8 , Al 2 MoW 2 O 12 , Y 2 MoW 2 O 12 , YAlMoW 2 O 12 and mixtures thereof.

17. Composite ceramic according to claim 1 , in which the molar ratio of the conversion phosphor to the further material is in the range from 1:1 to 5:1.

18. Composite ceramic which comprises a conversion phosphor and a further material, wherein the further material is a tungstate or molybdate and has a negative coefficient of thermal expansion.

19. Composite material according to claim 18 , in which the further material is a tungstate or molybdate, which is selected from the group consisting of Al 2 W 3 O 12 , Y 2 W 3 O 12 , YAlW 3 O 12 , ZrW 2 O 8 , Al 2 Mo 3 O 12 , Y 2 Mo 3 O 12 , YAlMo 3 O 12 , ZrMo 2 O 8 , Al 2 WMo 2 O 12 , Y 2 WMo 2 O 12 , YAlWMo 2 O 12 , ZrWMoO 8 , Al 2 MoW 2 O 12 , Y 2 MoW 2 O 12 , YAlMoW 2 O 12 and mixtures thereof.

Assignees

• Merck Patent Gmbh

Inventors

• Winkler Holger
• Juestel Thomas
• Plewa Julian

Classifications

• C09K11/77744

  Aluminosilicates · CPC title

• C09K11/7774

  Aluminates · CPC title

• C04B2235/80

  Phases present in the sintered or melt-cast ceramic products other than the main phase · CPC title

• C04B35/62807

  Silica or silicates · CPC title

• C04B2235/661

  Multi-step sintering · CPC title