Additive sintering and post-ammonolysis of dielectric BaTaO2N oxynitride perovskite

The sintering and thermal stability of BaTaO2N oxynitride perovskite were investigated as an alternative to SrTaO2N dielectric ceramics. The decomposition behaviors of the perovskites were similar, and the temperatures were slightly lower for BaTaO2N than for SrTaO2N. A BaTaO2N compact containing 2.5 wt% BaCO3 sintering aid was sintered at 1400 °C in 0.2 MPa N2. Post-ammonolysis was necessary for the sintered black ceramics to recover the original red color. The insulating post-ammonolysis product with a relative density RD = 73.0% showed a real relative permittivity εr = 620 and a tanδ = 0.4 at 102 Hz, which changed slightly to εr = 320 with tanδ = 2.0 × 10−2 at 108 Hz. The porosity was necessary to eliminate the electronic contribution affected on the extremely large values reported by Kim et al. in 2004 [1]. BaTaO2N ceramics showed better dielectric performance than SrTaO2N ceramics and it changed a little at temperatures up to 150 °C.