Structure and microwave dielectric properties of Ba1−xSrxMg2V2O8 ceramics

The Ba1−xSrxMg2V2O8 (0≤x≤0.4) microwave dielectric ceramics were fabricated by a standard solid-state reaction method. The formation of a continuous solid solution within the whole composition range was identified. The ceramic samples could be well densified in the temperature range of 885-975 °C in air for 4 h. The permittivity εr was found to increase with increasing ionic polarizabilities. The Q×f values were believed to be closely related with packing fraction and grain refinement. The Sr2+ substitution contributed to a monotonous increase of the A-site bond valence, such that the τf value experienced a considerable variation from negative to positive values. The optimum microwave dielectric properties of an εr of 13.3, a high Qxf of 86,640 GHz (9.6 Hz) and a near-zero τf of −6 ppm/°C could be yielded in the x=0.15 sample when sintered at 915 °C for 4 h.