Low temperature sintering of BaO–Sm2O3–4TiO2 ceramics

The effect of B2O3 and CuO on the sintering temperature and microwave dielectric properties of BaSm2Ti4O12 ceramics was investigated. The BaSm2Ti4O12 ceramics were able to be sintered at 1000 °C when B2O3 was added. This decrease in the sintering temperature of the BaSm2Ti4O12 ceramics upon the addition of B2O3 is attributed to the BaB4O7 second phase, whose melting temperature is around 900 °C. The B2O3 added BaSm2Ti4O12 ceramics alone were not able to be sintered below 1000 °C, but were sintered at 875 °C when CuO was added. BaCu(B2O5) second phase might be responsible for the decrease in the sintering temperature of the CuO and B2O3 added BaSm2Ti4O12 ceramics. The BaSm2Ti4O12 + 10.0 mol% B2O3 + 20.0 mol% CuO ceramics sintered at 875 °C for 2 h have good microwave dielectric properties of ɛr = 61.47, Q × f = 4256 GHz and τf = −9.25 ppm/°C. The BaCu(B2O5) is also a good additive for decreasing the sintering temperature of the BaSm2Ti4O12 ceramics.