Low temperature sintering of the Ba2Ti9O20 ceramics using B2O3/CuO and BaCu(B2O5) additives

The effects of B2O3/CuO and BaCu(B2O5) additives on the sintering temperature and microwave dielectric properties of Ba2Ti9O20 ceramics were investigated. The B2O3 added Ba2Ti9O20 ceramics were not able to be sintered below 1000 °C. However, when both CuO and B2O3 were added, they were sintered below 900 °C and had the good microwave dielectric properties. It was suggested that a liquid phase with the composition of BaCu(B2O5) was formed during the sintering and assisted the densification of the Ba2Ti9O20 ceramics at low temperature. BaCu(B2O5) powders were produced and used to reduce the sintering temperature of the Ba2Ti9O20 ceramics. Good microwave dielectric properties of Qxf = 16,000 GHz, ɛr = 36.0 and τf = 9.11 ppm/°C were obtained for the Ba2Ti9O20 ceramics containing 10.0 mol% BaCu(B2O5) sintered at 875 °C for 2 h.