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.

A facile method was successfully developed to prepare perovskite-type metal oxynitrides, LaTiO 2 N, from La 2 Ti 2 O 7 as a precursor in an atmosphere of N 2 . Urea was employed as a solid-state nitriding agent, instead of gaseous NH 3 , to increase the safety of the reaction. The hydrothermally prepared La 2 Ti 2 O 7 precursor had a nanosheet morphology and contained La(OH) 3 as a by-product. Through the optimization of reaction conditions including heat-treatment temperature and content [a]

No abstract