Method of producing beta-sialon fluorescent material

Patent metadata

Field	Value
Publication number	US-11753302-B2
Application number	US-202217937766-A
Country	US
Kind code	B2
Filing date	Oct 3, 2022
Priority date	Sep 27, 2019
Publication date	Sep 12, 2023
Grant date	Sep 12, 2023

Abstract

Provided a method of producing a β-sialon fluorescent material having excellent emission intensity. The method includes providing a first composition containing aluminum, an oxygen atom, and a europium-containing silicon nitride, heat treating the first composition, contacting the heat-treated composition and a basic substance to obtain a second composition, and contacting the second composition resulting from contacting the heat-treated composition with the basic substance and an acidic liquid medium containing an acidic substance.

First claim

What is claimed is:

1. A method of producing a β-sialon fluorescent material, the method comprising:
providing a first composition containing aluminium, an oxygen atom, and a europium-containing silicon nitride;
pulverizing the first composition with a europium compound to obtain a pulverized product;
second heat treating in a nitrogen atmosphere the pulverized product to obtain a second heat treated composition;
further first heat treating the second heat treated composition;
contacting the first heat-treated composition and a basic substance; and
contacting the composition contacted with the basic substance and an acidic liquid medium containing an acidic substance.

2. The method according to claim 1 , wherein the basic substance contains at least one selected from the group consisting of alkali metal hydroxides and ammonia.

3. The method according to claim 1 , wherein the contacting of the first heat-treated composition and the basic substance is carried out at a temperature of from 50° C. to 650° C.

4. The method according to claim 1 , wherein the contacting of the first heat-treated composition and the basic substance includes contacting at a first temperature, and contacting at a second temperature that is higher than the first temperature.

5. The method according to claim 1 , wherein the acidic liquid medium contains water and at least one acidic substance selected from the group consisting of hydrochloric acid, nitric acid, and sulfuric acid.

6. The method according to claim 1 , wherein the acidic liquid medium contains the acidic substance in an amount of from 0.1% by weight to 35% by weight.

7. The method according to claim 1 , wherein the contacting of the first heat-treated composition and the basic substance includes mixing the first heat-treated composition and a solution containing the basic substance and a solvent, and at least partially removing the solvent.

8. The method according to claim 1 , wherein the basic substance to be contacted with the first heat-treated composition is 0.5% by weight or more relative to the heat-treated composition.

9. The method according to claim 1 , wherein the first heat treating of the second heat treated composition is carried out in presence of a europium compound.

10. The method according to claim 1 , wherein the first heat treating of the second heat treated composition is carried out at a temperature of from 1300° C. to 1600° C.

11. The method according to claim 1 , wherein the first heat treating of the second heat treated composition is carried out in a rare gas atmosphere.

12. The method according to claim 1 , wherein the providing of the first composition includes heat treating a mixture containing an aluminium compound, a europium compound, and silicon nitride.

13. The method according to claim 1 , wherein the pulverized product has a specific surface area of 0.20 m 2 /g or more.

14. The method according to claim 1 , wherein the first composition is represented by a formula:
Si 6-z Al z O z N 8-z :Eu,

wherein z satisfies 0<z<4.2.

15. The method according to claim 1 , wherein a heat treating temperature of the second heat treating is from 1800° C. to 2100° C.

16. The method according to claim 1 , wherein a pressure of the second heat treating is a gauge pressure of from 0.1 MPa to 200 MPa.

17. The method according to claim 1 , wherein the europium compound to be pulverized with the first composition comprises at least one selected from the group consisting of oxides, hydroxides, nitrides, oxynitrides, fluorides, and chlorides containing europium.

18. The method according to claim 1 , wherein the pulverized product has a mole ratio of the europium compound to the first composition of 0.01% by mole or more and 5% by mole or less.

Assignees

• Nichia Corp

Inventors

• Aoyagi Kenichi
• Kaide Takashi
• Takahashi Yuya
• Hosokawa Shoji

Classifications

• C09K11/0883 Primary

  Arsenides; Nitrides; Phosphides · CPC title

• C01B21/0826 Primary

  Silicon aluminium oxynitrides, i.e. sialons · CPC title

• C09K11/77348

  Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides · CPC title

• C01F17/30

  Compounds containing rare earth metals and at least one element other than a rare earth metal, oxygen or hydrogen, e.g. La4S3Br6 (C01F17/247 - C01F17/294 take precedence) · CPC title

• C09K11/7734

  Aluminates · CPC title