Low temperature sintering and microwave dielectric properties of Ba2Ti9O20 ceramics using glass additions

Abstract The effects of glass additions on the microwave dielectric properties and the microstructures of Ba 2 Ti 9 O 20 ceramics were investigated. The simple glasses B 2 O 3 and SiO 2 and the commercial glass PbO–B 2 O 3 –SiO 2 (PBS) were selected as liquid phase sintering aids to lower the sintering temperature of Ba 2 Ti 9 O 20 ceramics. With glass additions, the sintering temperatures can be effectively lowered. The dielectric properties of Ba 2 Ti 9 O 20 ceramics with glass additions are strongly dependent on the densification, the microstructure, and the reaction between glasses and ceramics. Ba 2 Ti 9 O 20 ceramics without glass addition sintered at 1380°C has a dielectric constant e r = 38.8, a quality factor Q = 7200 at 6.0 GHz, and a temperature coefficient of resonant frequency τ f = 4 ppm/°C. Among these glasses, 5 wt% B 2 O 3 added Ba 2 Ti 9 O 20 can be sintered to achieve theoretical densities of 96 and 95% at 1100 and 1200°C, and gives e r values of 36.5 and 36 together with Q values of 3200 and 6700 (at 6 GHz), respectively. Results of XRD analysis and scanning electron microscopy are also presented.