Effects of BaCu(B2O5) on sintering characteristics and microwave dielectric properties of CaWO4 ceramics

The effects of BaCu(B2O5) (BCB) addition on the sintering characteristics and microwave dielectric properties of CaWO4 were investigated by the solid-state ceramic route. BCB addition effectively decreased the sintering temperature of CaWO4 from 1150 °C to 875 °C and only slightly degraded the microwave dielectric properties. BCB addition also greatly influenced the densification and grain size of CaWO4+x wt% BCB (0.06≤x≤0.14) ceramics. Some pits existed on the grain surface possibly because of the volatilization of BCB. For the ceramics sintered at 875 °C, Q×f values first increased and then decreased with the increase of x. With x=0.12, the sample presented excellent microwave dielectric properties of εr=9.547, Q×f=6.07×104 GHz, and τf=−41 ppm/°C.