Effect of mineralizers on formation of tantalum(V) nitride (Ta₃N₅) with heat-treatment of tantalum(V) oxide-aluminum nitride mixtures without flowing ammonia

Abstract

Ta(V) nitride (Ta₃N₅) powders for non-toxic red pigments were prepared by heat-treatment of mixed powders of Ta(V) oxide, aluminum nitride and alkali fluorides in a nitrogen atmosphere without flowing ammonia. This synthetic method is environmentally friendly as compared with such conventional methods as ammonolysis with large amounts of flowing ammonia. In this study, the effect of mineralizers on formation of tantalum(V) nitride (Ta₃N₅) with heat-treatment of Ta₂O₅–AlN mixtures was examined. The results revealed that the formation of Ta₃N₅ was promoted by co-doping with potassium fluoride (KF) and lithium fluoride as mineralizers. Doping with KF led to improvement of the chroma of the powders by controlling the grain growth of Ta₃N₅ and developing the facets of the grains.