B2O3 additives on sintering and microwave dielectric behaviors of Mg4Nb2O9 ceramics synthesized through the aqueous sol–gel Process

Abstract

The relationships between the sintering temperatures and the microwave dielectric properties of (1−x)Mg4Nb2O9-xB2O3 (x = 0.5–10 wt. %) compounds were investigated by the sol–gel method in order to reduce the sintering temperature in this study. A suitable amount of B2O3 doping was effective in allowing low sintering temperatures without a little detrimental effect on these dielectric properties of the Mg4Nb2O9 compounds. The variations in the dielectric constant (er) and the quality factor (Q·f) of the Mg4Nb2O9 compounds depended on the amount of B2O3 doping and the sintering temperature. As a result, a er value of ~12.8 and a Q·f value of ~142,570 GHz were obtained when the Mg4Nb2O9 compound with x = 3% was sintered at 1,200 °C for 4 h. The temperature coefficient of resonant frequency (τf) of the 3%-B2O3 doping Mg4Nb2O9 compound slightly changed from −33 to −48 ppm/°C with an increased sintering temperature.