Effects of CaTiO3 addition on the densification and microwave dielectric properties of BiSbO4 ceramics

Abstract In this study, the effects of CaTiO 3 addition on the sintering characteristics and microwave dielectric properties of BiSbO 4 were investigated. Pure BiSbO 4 achieved a sintered density of 8.46 g/cm 3 at 1100 °C. The value of sintered density decreased with increasing CaTiO 3 , and sintering at a temperature higher than 1100 °C led to a large weight loss (>2 wt%) caused by the volatile nature of the compound. Samples either sintered above 1100 °C or with a CaTiO 3 content exceeding 3 wt% showed poor densification. SEM micrographs revealed microstructures with bimodal grain size distribution. The size of the smaller grains ranged from 0.5 to 1.2 μm and that of the larger grains between 3 and 7 μm. The microwave dielectric properties of the (1− x ) BiSbO 4− x CaTiO 3 ceramics are dependent both on the x value and on the sintering temperature. The 99.0 wt% BiSbO 4 –1.0 wt% CaTiO 3 ceramic sintered at 1100 °C reported overall microwave dielectric properties that can be summarized as e r ≈21.8, Q × f ≈61,150 GHz, and τ f ≈−40.1 ppm/°C, all superior to those of the BiSbO 4 ceramics sintered with other additives.