Microwave dielectric properties of (Ba1−xSrx)(Mg0.5W0.5)O3 ceramics

The densification, microstructural evolution and microwave dielectric properties of (Ba1−xSrx)(Mg0.5W0.5)O3 ceramics with x=0, 0.25, 0.5 and 0.75 are investigated in this study. The sintering temperature of the (Ba1−xSrx)(Mg0.5W0.5)O3 is significantly reduced from 1575 °C to 1400 °C as the x value increases from 0 to 0.25 and 0.50; this result is accompanied by the formation of the (Ba1−ySry)WO4 phase and a small quantity of second phase surrounding the grains. The grain size of the (Ba1−xSrx)(Mg0.5W0.5)O3 ceramics is increased by raising the Sr2+ content, which significantly lowers the sintering temperature. The microstructure of the (Ba0.75Sr0.25)(Mg0.5W0.5)O3 ceramic displays the smallest average grain size of approximately 0.8 μm, with a narrow grain size distribution. Without long annealing time, very high Q×f values are obtained for the (Ba1−xSrx)(Mg0.5W0.5)O3 ceramics sintered at 1400-1575 °C for a duration of only 2 h. The (Ba0.75Sr0.25)(Mg0.5W0.5)O3 ceramic sintered at 1400 °C results in the best microwave dielectric properties, including εr of 20.6, Q×f of 152,600 GHz and τf of +24.0 ppm/°C.