Phosphor composition

Patent metadata

Field	Value
Publication number	US-10767111-B2
Application number	US-201916296818-A
Country	US
Kind code	B2
Filing date	Mar 8, 2019
Priority date	Nov 17, 2008
Publication date	Sep 8, 2020
Grant date	Sep 8, 2020

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.

First claim

The invention claimed is:

1. A method of making a phosphor composition that down-converts photons in the blue and ultraviolet portions of the visible spectrum into photons in the longer wavelength portions of the visible spectrum, the method comprising:
forming a mixture comprising:
a cation from the group consisting of calcium, strontium, lithium, sodium, potassium, rubidium, cesium, magnesium, barium, scandium, yttrium, lanthanum, gadolinium, and lutetium; with
a cation from the group consisting of aluminum, silicon, boron, gallium, carbon, germanium, and phosphorus; with
an anion selected from the group consisting of nitrogen, sulfur, chlorine, bromine, and iodine; and with an activator selected from the group of europium (II), cerium (Ill), ytterbium (II), samarium (II) and manganese (II);

heating the mixture in the presence of a forming gas at or near atmospheric pressure; and
forming from the mixture a first phase comprising a nitride phosphor.

2. The method of claim 1 , wherein the nitride phosphor comprises a nominal composition of Ca 1-x-y Sr x EU y AISiN 3 where 0<X<1 and 0<y<1.

3. The method of claim 2 , wherein x is between 0.50 and 0.70.

4. The method of claim 3 , wherein x is between about 0.55 and 0.67.

5. The method of claim 2 , wherein y is between about 0.013 and 0.017.

6. The method of claim 1 , further comprising forming from the mixture a second phase.

7. The method of claim 6 , wherein the second phase comprises silicon aluminum oxynitride.

8. The method of claim 7 , wherein the silicon aluminum oxynitride comprises Si 2 Al 4 O 4 N 4 .

9. The method of claim 6 , further comprising forming a third phase from the mixture, the third phase comprising aluminum nitride.

10. The method of claim 1 comprising heating the mixture in the substantial absence of water and oxygen.

11. The method of claim 1 comprising heating the mixture in a refractory crucible that is substantially inert in the presence of the forming gas mixture.

Assignees

• Cree Inc

Inventors

• Collins Brian T
• Hussell Christopher P
• Emerson David T
• Le Toquin Ronan P

Classifications

• C09K11/77348 Primary

  Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides · CPC title

• C04B35/58 Primary

  based on borides, nitrides, {i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides} or silicides {(containing free binder metal C22C29/00)} · CPC title

• C09K11/08 Primary

  containing inorganic luminescent materials · CPC title

• Y02B20/00

  Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps · CPC title

• C04B35/597

  based on silicon oxynitride, {e.g. SIALONS} · CPC title