Phosphor particles with a protective layer, and method for producing the phosphor particles with the protective layer

Patent metadata

Field	Value
Publication number	US-11021652-B2
Application number	US-202016911050-A
Country	US
Kind code	B2
Filing date	Jun 24, 2020
Priority date	Mar 6, 2015
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

Phospher particles with a Protective Layer and a method for producing phosphor particles with a protective layer are disclosed. In an embodiment the method includes treating Si-containing and/or Al-containing phosphor with an acid solution, wherein a pH value of the acid solution is maintained within a range of pH 3.5 to pH 7 for a period of at least 1 h, wherein an Si-containing layer is formed on the phosphor particles, wherein the Si-containing layer has a higher content of Si on a surface than the phosphor particles, and/or wherein an Al-containing layer is formed on the phosphor particles, wherein the Al-containing layer has a modified content of aluminum on the surface than the phosphor particles and tempering the treated phosphor particles at a temperature of at least 100° C. thereby producing the protective layer.

First claim

What is claimed is:

1. A method for producing phosphor particles of a Si-containing and/or Al-containing phosphor with a protective layer, the method comprising:
treating the Si-containing and/or Al-containing phosphor with an acid solution;
applying at least one of the following pH control methods:
adding an acid as a function of a pH value of the acid solution;
adding a buffer solution; and
adding a defined quantity of acid solution as a function of a quantity of phosphor, wherein a pH value of the acid solution is maintained within a range of pH 3.5 to pH 7 for a period of at least 1 h, wherein a Si-containing layer is formed on the phosphor particles, wherein the Si-containing layer has a higher content of Si on a surface than the phosphor particles, and/or wherein an Al-containing layer is formed on the phosphor particles, and wherein the Al-containing layer has a modified content of aluminum on the surface than the phosphor particles; and

tempering the treated phosphor particles at a temperature of at least 100° C. thereby producing the protective layer.

2. The method according to claim 1 , wherein treating the Si-containing and/or Al-containing phosphor with the acid solution comprises maintaining a pH value in a range of pH 4 to pH 6.5.

3. The method according to claim 1 , wherein treating the Si-containing and/or Al-containing phosphor with the acid solution comprises applying the acid solution for a period of 4 h to 5 h.

4. The method according to claim 1 , wherein tempering the treated phosphor particles comprises performing tempering in an atmosphere containing oxygen.

5. The method according to claim 1 , wherein the Si-containing and/or Al-containing phosphor further comprises alkaline earth ions, and wherein the protective layer has a lower content of alkaline earth ions than the phosphor particles.

6. The method according to claim 1 , wherein the Si-containing and/or Al-containing phosphor contains an inorganic substance, wherein the substance includes in its composition at least element D, element A1, element AX, element SX and element NX, wherein the element D represents one or more elements from the group consisting of Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Li, Na, K, Rb, Cs and Yb, wherein the element A1 represents one or more elements from divalent metals that are not included in the element D, wherein the element SX represents one or more elements from tetravalent metals containing Si, wherein the element AX represents one or more elements from trivalent metals containing Al, wherein the element NX represents one or more elements selected from the group consisting of O, N, S, C, Cl, and F, wherein the substance has the same crystal structure as Sr(Sr a Ca 1−a )Si 2 Al 2 N 6 , and wherein a value of a is between 0.6 and 1.

7. The method according to claim 1 , wherein the Si-containing and/or Al-containing phosphor is a phosphor with the general formula Sr(Sr a M 1−a )Si 2 Al 2 N 6 :D, wherein element M is selected from the group consisting of Ca, Ba, Zn and Mg, wherein element D is selected from the group consisting of Eu and Ce, and wherein a value of a is between 0.6 and 1.0.

8. A method for producing phosphor particles of a Si-containing and/or Al-containing phosphor with a protective layer, the method comprising:
treating the Si-containing and/or Al-containing phosphor with an acid solution, wherein a pH value of the acid solution is maintained within a range of pH 3.5 to pH 7 for a period of at least 1 h, wherein a Si-containing layer is formed on the phosphor particles, wherein the Si-containing layer has a higher content of Si on a surface than the phosphor particles, and/or wherein an Al-containing layer is formed on the phosphor particles, and wherein the Al-containing layer has a modified content of aluminum on the surface than the phosphor particles; and
tempering the treated phosphor particles at a temperature of at least 100° C. thereby producing the protective layer,
wherein tempering the treated phosphor particles comprises performing tempering in an atmosphere containing oxygen.

9. The method according to claim 8 , wherein tempering the treated phosphor particles comprises performing tempering at a heating rate between 1° C./h and 100° C./h.

10. A method for producing phosphor particles of a Si-containing and/or Al-containing phosphor with a protective layer, the method comprising:
treating the Si-containing and/or Al-containing phosphor with an acid solution, wherein a pH value of the acid solution is maintained within a range of pH 3.5 to pH 7 for a period of at least 1 h, wherein a Si-containing layer is formed on the phosphor particles, wherein the Si-containing layer has a higher content of Si on a surface than the phosphor particles, and/or wherein an Al-containing layer is formed on the phosphor particles, and wherein the Al-containing layer has a modified content of aluminum on the surface than the phosphor particles; and
tempering the treated phosphor particles at a temperature of at least 300° C. and at most 450° C. thereby producing the protective layer.

11. The method according to claim 10 , wherein tempering the treated phosphor particles comprises tempering the treated phosphor particles at temperatures between 300° C. to 350° C.

12. The method according to claim 10 , wherein treating the Si-containing and/or Al-containing phosphor with an acid solution comprises applying at least one of the following pH control methods:
adding an acid as a function of the pH value of the acid solution;
adding a buffer solution; and
adding a defined quantity of acid solution as a function of a quantity of phosphor.

13. A plurality of phosphor particles with a protective layer located on at least parts of a surface of the phosphor particles,
wherein the phosphor particles comprise a Si-containing and/or Al-containing phosphor,
wherein the protective layer has a content of Si that is increased by at least 40 at. % compared with a phosphor and/or a content of Al that is reduced by at least 10% compared with the phosphor,
wherein the phosphor particles comprise a phosphor containing an inorganic substance, which includes in its composition at least element D, element A1, element AX, element SX and element NX,
wherein the element D represents one or more elements from the group consisting of Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Li, Na, K, Rb, Cs and Yb,
wherein the element A1 represents one or more elements from divalent metals that are not included in the element D,
wherein the element SX represents one or more elements from tetravalent metals containing Si,
wherein the element AX represents one or more elements from trivalent metals containing Al,
wherein the element NX represents one or more elements from the group consisting of O, N, S, C, Cl, and F,
wherein the substance has the same crystal structure as Sr(Sr a Ca 1−a )Si 2 Al 2 N 6 , and
wherein a value of a is between 0.6 and 1.0.

14. The plurality of phosphor particles according to claim 13 , wherein the phosphor particles additionally comprise alkaline earth ions, and wherein the protective layer has a content of alkaline earth ions that is reduced by at least 40 at. % compared with the phosphor.

15. The plurality of phosphor particles according to claim 13 , wherein a Si-content of the protective layer is increased by at least 40 at. % compared with the phosphor.

16. The plurality of phosphor particles according to claim 13 , wherein an Al-content of the protective layer is reduced by at least 10 at. % to a maximum of 50 at. % compared with the phosphor.

1

Assignees

• Osram Opto Semiconductors Gmbh
• Osram Gmbh

Inventors

• Fiedler Tim
• Tragl Sonja
• Lange Stefan

Classifications

• C09K11/77348

  Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides · CPC title

• C09K11/7734

  Aluminates · CPC title

• C09K11/025 Primary

  non-luminescent particle coatings or suspension media · CPC title

• C09K11/0883

  Arsenides; Nitrides; Phosphides · CPC title