Rare earth-activated aluminum nitride powders and method of making
First Claim
1. A method of making a rare earth-activated aluminum nitride, comprising:
- (a) forming an aqueous mixture containing aluminum and a rare earth metal;
(b) precipitating a mixed hydroxide of aluminum and the rare earth metal;
(c) reacting the mixed hydroxide with ammonium fluoride to form a fluoride compound of aluminum and the rare earth metal;
(d) drying the fluoride compound; and
(e) reacting the dried fluoride compound with ammonia gas to form the rare earth-activated aluminum nitride.
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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.
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Citations
16 Claims
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1. A method of making a rare earth-activated aluminum nitride, comprising:
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(a) forming an aqueous mixture containing aluminum and a rare earth metal; (b) precipitating a mixed hydroxide of aluminum and the rare earth metal; (c) reacting the mixed hydroxide with ammonium fluoride to form a fluoride compound of aluminum and the rare earth metal; (d) drying the fluoride compound; and (e) reacting the dried fluoride compound with ammonia gas to form the rare earth-activated aluminum nitride. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of making a rare earth-activated aluminum nitride, comprising:
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(a) forming an aqueous mixture by dissolving aluminum nitrate and a nitrate of a rare earth metal; (b) precipitating a mixed hydroxide of aluminum and the rare earth metal by adding ammonium hydroxide to the aqueous mixture; (c) reacting the mixed hydroxide with a stoichiometric excess of ammonium fluoride at an elevated temperature to form a hexafluoride compound of aluminum and the rare earth metal; (d) drying hexafluoride compound; and (e) reacting the dried hexafluoride compound with ammonia gas to form the rare earth-activated aluminum nitride. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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Specification