Effect of WO₃ on the microstructure and microwave characteristics of Ba(Zn_1/3Nb_2/3)O₃ ceramics

The microwave dielectric properities of the system, Ba_1+x(Zn_1/3Nb_2/3)O₃ + xWO₃ with 0 < x < 0.06, were investigated to find out the effect of the addition of WO₃ on the microwave dielectric properties of Ba(Zn_1/3Nb_2/3)O₃ (BZN). According to the energy dispersive spectroscopy (EDS) analysis of the sintered specimens, most of tungsten ions react with Ba ions resulting in the formation of BaWO₄ phase and some are dissolved into BZN. The dielectric constant of the system steadily decreases from 41 to 36 and the temperature coefficient of resonant frequency (T_f) decreases from 28 to 18 ppm/°C as x varies from 0 to 0.06. This is thought as a result of the formation of BaWO₄. The Q-values are significantly improved with the addition of minor amount of WO₃. The highest Q x f achieved in this investigation was about 75,000 for x = 0.02 ∼ 0.06.