Synthesis of perovskite-type oxynitrides SrNb(O,N)3 and CaTa(O,N)3 using carbon nitride

The synthesis of oxynitride perovskites based on the use of gaseous ammonia as the nitrogen source requires high reaction temperatures and long durations. In the resent work, reduction and nitridation reactions using carbon nitride (C3N4) were employed to prepare SrNbO2N and CaTaO2N from their oxide precursors, without the use of ammonia. The phase evolution behaviors and the reaction mechanisms were investigated by acquiring thermogravimetric and X-ray diffraction data. The formation of metal cyanamide as an intermediate was found to be vital to realizing low-temperature synthesis of these compounds. Scanning electron microscopy observations also indicated that the particle sizes of the oxynitrides prepared using C3N4 were smaller than those obtained by ammonolysis reactions, due to the low formation temperature of 800 °C associated with the present C3N4 process. © 2020 Elsevier Ltd and Techna Group S.r.l.