A facile method was successfully developed to prepare strontium-tantalum perovskite oxynitride, SrTaO 2 N, and its solid solutions. Urea was employed as a solid nitriding agent to eliminate the use of toxic NH 3 gas. In addition, utilization of sol-gel derived Ta 2 O 5 gel as a Ta precursor allowed for completion of nitridation within a shorter period and at a lower calcination temperature compared with the conventional ammonolysis process. Optimization of the reaction conditions, such as the urea content, allowed for production of solid solutions of SrTaO 2 N and Sr 1.4 Ta 0.6 O 2.9 . The products exhibited optical absorption and chromatic colors because of the narrower band gaps of oxynitrides compared with those of oxides. The O/N ratios of the solid solutions were easily adjusted by varying the amount of urea in the mixture of precursor. As a result, the colors of the products ranged from yellow to brown. The nitridation process and products developed in this study are interesting environmentally-benign alternatives to conventional inorganic pigments.

Calcium–tantalum based perovskite oxynitrides were successfully prepared without ammonolysis. The colour of La3+-doped CaTa(O,N)3 was comparable to that of CaTaO2N prepared by ammonolysis and inorganic yellow pigments using heavy metals.

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