| abstract |
Niobium or tantalum metal is produced by a process comprising (1) reaction of the corresponding oxide with ammonia to form the nitride and (2) decomposition of the nitride at elevated temperature and reduced pressure to form the metal. In the case of niobium, the reaction between the oxide and ammonia is preferably carried out in two stages, with initial formation of an oxynitride phase at a temperature of about 650* to 850*C, and subsequent further reaction of the oxynitride with ammonia at a temperature of about 1,100*-1,500*C to form the nitride phase. |