Optimized sintering properties and temperature stability of MgZrTa2O8 ceramics with CuO addition for microwave application

Abstract

Microwave dielectric ceramics CuO–modified MgZrTa2O8 were synthesized by the conventional solid-state reaction method. The effects of CuO additives on the sintering characteristics and microwave dielectric properties have been investigated. With CuO addition, the sintering temperature of MgZrTa2O8 ceramics can be effectively lowered from 1475 to 1375 °C without decreasing its dielectric properties obviously and the temperature coefficient of the resonant frequency of MgZrTa2O8 ceramics have been optimized to near-zero. The crystalline phase exhibited a wolframite crystal structure and no second phase was detected at low addition levels. The grain growth of CuO–modified MgZrTa2O8 ceramics was accelerated due to liquid phase effect. The relative dielectric constants (er) were correlated with apparent density and were not significantly different for all levels of CuO concentration. The quality factors (Q × ƒ) and temperature coefficient of resonant frequency (τƒ), which were strongly dependent on the CuO concentration, were analyzed by the grain size and the dielectric constant respectively. A best Q × ƒ value of 116400 GHz and τƒ value of −6.19 ppm/℃ were obtained for specimen with 0.05 wt% CuO addition at 1375 °C.