Direct synthesis of SrTaO2N from SrCO3/Ta3N5 involving CO evolution

SrTaO2N powder was prepared by a novel reaction between Ta3N5 and SrCO3, instead of the traditional nitridation of SrTaO3.5. The phase evolution and reaction mechanism during the reaction were investigated. The mixed gas evolution of CO, CO2 and N2 were observed in the heat-treatment of Ta3N5/SrCO3. The SrTaO2N product possessed an average particle size of 330 nm in a narrow distribution with the stoichiometric oxygen and nitrogen content. Its ceramics with various relative density were also fabricated by pressureless sintering of the as-prepared SrTaO2N powder, showing a high sinterability. The fully-annealed SrTaO2N bulks with a RD = 82.8% showed a relatively large dielectric constant and an improved dielectric loss.