Influence of V2O5 additions to Ba(Mg1/3Ta2/3)O3 ceramics on sintering behavior and microwave dielectric properties

The microstructures and the microwave dielectric properties of barium magnesium tantalate ceramics prepared by conventional mixed oxide route have been investigated. The prepared Ba(Mg1/3Ta2/3)O3 exhibited a mixture of cubic perovskite and a hexagonal superstructure with Mg and Ta showing 1:2 order in the B-site. It is found that low level doping of V2O5 (up to 0.5 wt.%) can significantly improve densification of the specimens and their microwave dielectric properties. The density of doped Ba(Mg1/3Ta2/3)O3 ceramics can be increased beyond 95% of its theoretical value by 1500 °C-sintering, which is caused by the liquid-phase effect of V2O5 addition. The detected second phase Ta2O5 was mainly the result of V5+ substitution in the ceramics. Dielectric constant (εr) and temperature coefficient of resonant frequency (τf) were not significantly affected, while the unloaded quality factors Q were effectively promoted by V2O5 addition due to the increase in B-site ordering. The εr value of 24.1, Q×f value of 149,000 (at 10 GHz) and τf value of 7.2 ppm/°C were obtained for Ba(Mg1/3Ta2/3)O3 ceramics with 0.25 wt.% V2O5 addition sintered at 1500 °C for 3 h.