Low temperature sintering and microwave dielectric properties of Ba 2Ti 9O 20 ceramics using glass additions

Abstract

The effects of glass additions on the microwave dielectric properties and the microstructures of Ba 2Ti 9O 20 ceramics were investigated. The simple glasses B 2O 3 and SiO 2 and the commercial glass PbO–B 2O 3–SiO 2 (PBS) were selected as liquid phase sintering aids to lower the sintering temperature of Ba 2Ti 9O 20 ceramics. With glass additions, the sintering temperatures can be effectively lowered. The dielectric properties of Ba 2Ti 9O 20 ceramics with glass additions are strongly dependent on the densification, the microstructure, and the reaction between glasses and ceramics. Ba 2Ti 9O 20 ceramics without glass addition sintered at 1380°C has a dielectric constant ε 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 2O 3 added Ba 2Ti 9O 20 can be sintered to achieve theoretical densities of 96 and 95% at 1100 and 1200°C, and gives ε 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.