Abstract
We investigated the phase evolution, microstructure, and microwave dielectric properties of Na- and Zr-doped Ba(Mg0.5W0.5)O3 [i.e., (Ba1-2xNa2x)(Mg0.5-xZrxW0.5)O3] ceramics. BaWO4 as a secondary phase was observed in all compositions, and it increased as the dopant concentration increased. All specimens revealed a dense microstructure. For the composition of x=0.01, polyhedral grains were observed. As the dopant concentration increased, the densification and the grain growth were promoted by a liquid phase. The quality factor(Q×f0) decreased remarkably, whereas the dielectric constant (εr) tended to decrease as the dopant concentration increased. The dielectric constant, quality factor, and temperature coefficient of the resonant frequency of the composition of x=0.01 sintered at 1,700℃ for 1 h were 18.6, 216,275 GHz, and -22.0 ppm/℃, respectively.
