Rare earth-activated aluminum nitride powders and method of making
US7935325B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Dec 20, 2006 |
| Grant date | May 3, 2011 |
| Priority date | — |
| Expiry date | Jul 20, 2027 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC04B2235/9661
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
Rare earth-activated aluminum nitride powders are made using a solution-based approach to form a mixed hydroxide of aluminum and a rare earth metal, the mixed hydroxide is then converted into an ammonium metal fluoride, preferably a rare earth-substituted ammonium aluminum hexafluoride ((NH4)3Al1-xRExF6), and finally the rare earth-activated aluminum nitride is formed by ammonolysis of the ammonium metal fluoride at a high temperature. The use of a fluoride precursor in this process avoids sources of oxygen during the final ammonolysis step which is a major source of defects in the powder synthesis of nitrides. Also, because the aluminum nitride is formed from a mixed hydroxide co-precipitate, the distribution of the dopants in the powder is substantially homogeneous in each particle.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.