Microwave dielectric properties of Ba[Mg(1−x)/3SnxTa2(1−x)/3]O3 (x = 0–0.25) ceramics

Ba[Mg(1−x)/3SnxTa2(1−x)/3]O3 (BMST, x = 0–0.25) ceramics were prepared by the solid-state reaction. The effect of Sn substitution on the structure, microstructure and microwave dielectric properties of Ba[Mg(1−x)/3SnxTa2(1−x)/3]O3 were investigated. The crystal symmetry increased with Sn4+ concentration from hexagonal to cubic structure and the ordered phase were transformed from the 1:2 ordered structure to the 1:1 ordered structure. These results suggested that Sn substitution not only contributed to lowering the sintering temperature but also adjusted the temperature coefficient of resonant frequency. Superior microwave dielectric properties (εr = 24.1, Q × f = 138,500 GHz and τf = +0.2 ppm/ °C) were achieved for Ba[Mg(1−x)/3SnxTa2(1−x)/3]O3 (x = 0.2) ceramics sintered at 1450 °C for 6 h.