# US 9,428,688 B2 · Phosphor composition

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- Number: US 9,428,688 B2
- Document ID: US9428688B2
- Status: Granted
- Kind: B2
- Application number: 12/271,945
- Filed: 2008-11-17
- Published: 2010-05-20
- Granted: 2016-08-30
- Earliest claimed: 2008-11-17
- Assignees: Cree, Inc.
- Applicants: Brian T. Collins; Christopher P. Hussell; David T. Emerson; Ronan P. Le Toquin
- Inventors: Brian T. Collins; Christopher P. Hussell; David T. Emerson; Ronan P. Le Toquin
- Web page: https://patentgrep.com/patent/US9428688B2

## CPC

- C09K 11/77348: {Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides}
- C04B 35/58: based on borides, nitrides, {i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides} or silicides {(containing free binder metal C22C29/00)}
- C04B 35/581: based on aluminium nitride
- C04B 35/584: based on silicon nitride
- C04B 35/597: based on silicon oxynitride, {e.g. SIALONS}
- C09K 11/025: {non-luminescent particle coatings or suspension media}
- C09K 11/0883: {Arsenides; Nitrides; Phosphides}
- C04B 35/591: obtained by reaction sintering
- C04B 35/593: obtained by pressure sintering
- C04B 35/5935: {obtained by gas pressure sintering}
- C04B 2235/3224: Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
- C04B 2235/3852: Nitrides, e.g. oxynitrides, carbonitrides, oxycarbonitrides, lithium nitride, magnesium nitride
- C04B 2235/3865: Aluminium nitrides
- C04B 2235/3869: Aluminium oxynitrides, e.g. AlON, sialon
- C04B 2235/3873: Silicon nitrides, e.g. silicon carbonitride, silicon oxynitride
- C04B 2235/445: Fluoride containing anions, e.g. fluosilicate
- C09K 11/7728: {containing europium}
- Y02B 20/00: Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

A method is disclosed for forming a blended phosphor composition. The method includes the steps of firing precursor compositions that include europium and nitrides of at least calcium, strontium and aluminum, in a refractory metal crucible and in the presence of a gas that precludes the formation of nitride compositions between the nitride starting materials and the refractory metal that forms the crucible. The resulting compositions can include phosphors that convert frequencies in the blue portion of the visible spectrum into frequencies in the red portion of the visible spectrum.

## Claims

### Claim 1

A method of making a phosphor composition, the method comprising:
forming a powder mixture comprising Ca3N2, Sr2N, AlN, Si3N4 and
a europium source composition;
heating the powder mixture at or near atmospheric pressure in the presence of a forming gas mixture comprising nitrogen and hydrogen; and
forming from the powder mixture a first phase comprising a nitride phosphor having a nominal composition of Ca1-x-ySrxEuyAlSiN3, where 0<x<1 and 0<y<1, and a second phase comprising silicon aluminum oxynitride.

### Claim 2 (depends on 1)

The method according to claim 1 comprising:
heating the powder mixture in a refractory crucible that is substantially inert in the presence of the forming gas mixture for a time sufficient to produce a phosphor composition that will down convert photons in the blue and ultraviolet regions of the spectrum into photons in the longer wavelength regions of the visible spectrum.

### Claim 3 (depends on 1)

The method according to claim 1, comprising heating the powder mixture at atmospheric pressure.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the powder mixture is heated to a temperature of between about 1500 to 180° C.

### Claim 5 (depends on 1)

The method according to claim 1 wherein the silicon aluminum oxynitride comprises Si2Al4O4N4.

### Claim 6 (depends on 1)

The method according to claim 1 wherein the forming gas mixture comprises between about 5% and 10% hydrogen and a balance nitrogen.

### Claim 7 (depends on 1)

The method according to claim 1 wherein x is between about 0.5 and 0.7.

### Claim 8 (depends on 7)

The method according to claim 7 wherein x is between about 0.55 and 0.67.

### Claim 9 (depends on 1)

The method according to claim 1 wherein y is between about 0.013 and 0.017.

### Claim 10 (depends on 1)

The method according to claim 1 wherein the forming gas mixture includes about 95% nitrogen and about 5% hydrogen.

### Claim 11 (depends on 1)

The method according to claim 1 wherein the heating is carried out at a temperature of 1750° C.

### Claim 12 (depends on 1)

The method according to claim 1 wherein the heating comprises at least three heating steps at increasingly higher temperatures.

### Claim 13 (depends on 12)

The method according to claim 12 comprising a first heating step at 800° C., a second heating step at 1200° C., and a third heating step above 1600° C.

### Claim 14 (depends on 13)

The method according to claim 13 wherein ramping steps of about 350° C. per hour are employed between the first, second and third heating steps.

### Claim 15 (depends on 13)

The method according to claim 13 wherein the first and second heating steps are carried out for one hour each, and wherein the third heating step is carried out for two hours.