Effects of Bi2Mo2O9 addition on the sintering characteristics and microwave dielectric properties of BiSbO4 ceramics

In this study, densification, microstructural evolution and microwave dielectric properties of (1 − x)BiSbO4–xBi2Mo2O9 ceramics (x = 0–0.25) were investigated. Bi2Mo2O9 was selected as the sintering aid as well as the modifier of the dielectric properties for BiSbO4 ceramic. In comparison with pure BiSbO4 densified at 1100 °C, the 0.75BiSbO4–0.25Bi2Mo2O9 composites emerged to reach maximum sintering density at 775 °C. No other second phase was detected while the microstructure exhibited a bimodal grain size distribution as both 1–2 μm large grains of Bi2Mo2O9 and 0.2–0.5 μm fine grains of BiSbO4 were observed. The ceramic with the best performance in terms of microwave dielectric properties in this system is found to be the 0.82BiSbO4–0.18Bi2Mo2O9 composite, which reports a ɛr of 24.3, a Q × f of 24,019 GHz, and a τf of −4 ppm/°C when sintered at 825 °C.