Low temperature sintering and microwave dielectric properties of BaO–0.6ZnO–2.9TiO2 ceramics using BaCu(B2O5) addition

In this paper, the effect of BaCu(B2O5) addition on the sintering process, phase composition, microstructure and microwave dielectric properties of BaO–0.6ZnO–2.9TiO2 ceramics were investigated by the conventional solid-state reaction technique. It was suggested that the liquid phase of BaCu(B2O5) was responsible for the densification of the BaO–0.6ZnO–2.9TiO2 ceramics at approximate 900 °C. Using EDX analysis the evaporating of boron was confirmed and Cu2+ most likely substituted for Zn2+ sites in the phases Ba4ZnTi11O27 and BaZn2Ti4O10. BaTiO3 phase appearing at the grain boundary as the derivative of BaCu(B2O5) had a considerable negative effect on the microwave dielectric properties. The variation tendency of dielectric constant was increased in accord with the trend between bulk densities and the sintering temperature. The maximum Q × f value of 15200 GHz was obtained for the specimen with 7 wt% BaCu(B2O5)The specimen with 7 wt% BaCu(B2O5) addition sintered at 900 °C for 1.5 h showed dense microstructure and had acceptable microwave dielectric properties: dielectric constant εr = 37, Q × f = 15200 GHz and the temperature coefficient of resonant frequency τf = −9.8 ppm/°C.