The phase transitions and dielectric properties of low temperature sintered ZnNb2O6–Zn3Nb2O8–TiTe3O8 microwave ceramics

ZnNb2O6–Zn3Nb2O8–TiTe3O8 ceramics were fabricated by conventional ceramic processing. The effects of TiTe3O8 on the microstructures and dielectric properties of 0.7ZnNb2O6–0.3Zn3Nb2O8 ceramics were investigated and the chemical reaction mechanisms of the phase transition were discussed. The results show that addition of TiTe3O8 will reduce the sintering temperature of ceramics. It is observed that ZnTiO3, Zn2TiO4 and ZnTeO3 phases coexist with ZnNb2O6 and Zn3Nb2O8 phases, which results from the decomposition and reaction between Zn3Nb2O8 and TiTe3O8. The morphology of ceramics changes significantly with increasing amounts of TiTe3O8. With increasing amount of TiTe3O8, the dielectric constant and the temperature coefficient of resonant frequency increase, while the Q × f value decreases. The optimized composition is 0.6(0.7ZnNb2O6–0.3Zn3Nb2O8)–0.4TiTe3O8, which can be sintered at 670 °C and shows the best microwave dielectric properties with τf of 3 ppm/°C.