Effect of B2O3 additives on sintering and microwave dielectric behaviors of 0.66Ca(Mg1/3Nb2/3)O3–0.34CaTiO3 ceramics

The effects of B2O3 additives on the microstructures and the microwave dielectric properties of complex perovskite 0.66Ca(Mg1/3Nb2/3)O3–0.34CaTiO3 ceramics were investigated. The B2O3 additives, acting as a sintering aid, can effectively lower the sintering temperature of the ceramics to as low as 1200 °C. No second phase was observed throughout the entire experiments. Moreover, boron was not found in the grains but residual at the boundaries indicating a liquid phase sintering. At 1250 °C, the 0.25 wt% B2O3-doped 0.66Ca(Mg1/3Nb2/3)O3–0.34CaTiO3 ceramics possesses a relative permittivity ɛr of 43.94, a Q × f value of 30,000 GHz (measured at 6.7 GHz) and a τf value of −1.9 ppm/°C. It exhibits a substantial temperature reduction (>200 °C) and compatible dielectric properties in comparison with that of un-doped one.