Direct synthesis of nearly single-phase BaTaO2N and CaTaO2N powders

Based on the previous work on SrTaO2N [Sun et al. (2014) J. Eur. Ceram. Soc.; doi: 10.1016/j.jeurceramsoc.2014.07.003], a facile method was developed to directly synthesize nearly single-phase powders of BaTaO2N and CaTaO2N by the heat-treatment of alkaline earth metal carbonate and tantalum (oxy)nitride in the atmosphere of N2, instead of the traditional nitridation of the corresponding oxides in NH3. The submicron-sized BaTaO2N agglomerates were obtained by firing a mixture of BaCO3/Ta3N5 at 850 °C in flowing N2. CaTaO2N product possessed an average particle size of 400 nm in a narrow distribution after firing CaCO3/TaON at 1000 °C. CaTaO2N with the higher purity was attained in the usage of TaON than in the case of Ta3N5.