The influence of ZrO2 doping on the microwave dielectric properties and microstructures of Bi2Mo2O9 ceramics

Bi2Mo2O9 (BMO) compounds have been found to possess an ultra-low sintering temperature and good microwave dielectric properties. Typically, pure BMO ceramics sintered at 620 °C can reach a maximum relative density with a permittivity of 38, a Q×f (f=resonant frequency, Q=1/dielectric loss at f) value of 14,100 GHz and a dielectric loss of 8×10−4. In the present study, Bi2Mo2O9 composites with 0.5–3 mol% ZrO2 doping were sintered at 620 °C and 640 °C, prepared by the conventional solid-state ceramic route and characterized systematically in terms of their density, phase compositions, microstructures and microwave dielectric properties. No secondary phase is observed in samples with 2 mol% ZrO2 addition sintered at 620 °C. The dielectric properties of Bi2Mo2O9 ceramics were improved by ZrO2 doping. Bi2Mo2O9 ceramics doped with 2 mol% ZrO2 exhibited the best microwave dielectric properties, with a permittivity of 39.2, a Q×f value of 15,443 GHz and τf of −6.7 ppm/°C after sintering at 620 °C.