The effect of transition metal oxides on the tunablility and microwave dielectric properties of Ba0.5Sr0.5TiO3–BaWO4 composite ceramics

Ba0.5Sr0.5TiO3–BaWO4 ceramics with transition metal ions acceptor Mn and donor V-doping are prepared by solid-state route and characterized systematically in terms of their phase compositions, microstructure and microwave dielectric properties. These dopants had a strong effect on microstructures of the ceramics. Curie temperatures of all samples are shifted and their dielectric peaks were broadened. Meanwhile, loss tangent of either the acceptor (Mn-doped) or the donor (V-doped) doped samples decreased at both low frequency (10 kHz) and microwave frequency at room temperature. Especially, the doped samples exhibit promising microwave dielectric properties, making them suitable candidates for applications in electrically tunable microwave devices.