Synthesis, Structure and Properties of Niobium Aluminum Oxynitride and Tantalum based Compound Prepared through Citrate Route

摘要

The oxynitrides with composition A_(1-x)B_x(O_yN_z) (A: Nb and Ta, B: Al) were studied in preparation through citrate route and NH3 nitridation. In the case of Nb, the product of x = 0.5 prepared at 1000 ℃ was a new compound of a = 0.435 nm with rock salt structure. In this structure, Al and Nb atoms were distributed randomly in the cation sites. Anion sites were also randomly occupied by oxide and nitride ions with some amount of vacancy. The chemical composition was represented as Nb_(0.56)Al_(0.44)O_(0.38)N_(0.37)□_(0.25) from Rietveld refinement and oxygen/ nitrogen measurement. In the case of Ta, monoclinic Ta_3N_5 crystallized with a small amount of Ta_4N_5 impurity at x = 0.5. Aluminum compound was co-present as amorphous impurity.