Effects of CuO Addition on the Microstructure and Microwave Dielectric Properties of MgTa_2O_6 Ceramics

摘要

MgTa_2O_6 powders with the tetragonal phase were synthesized by mixed oxide method at 1100°C with the molar ratios of MgO and Ta_2O_5 from 1:1 to 1.2:1. The microwave dielectric properties of sintered MgTa_2O_6 ceramics without additives at 1400°C for 6h, which consists of tetragonal and orthorhombic phases were investigated. The ceramic possesses a dielectric constant of 27.5, a high Q×f value of 156000 GHz and a temperature coefficient of resonant frequency of 21.6 ppm/°C at 6~(-10) GHz. Different amounts of CuO was used as sintering additives to lower the sintering temperature of MgTa_2O_6 ceramics. The effect of CuO doping on the microstructure, densification and the microwave dielectric properties of MgTa_2O_6 was studied. The results indicate that the 1-5 wt. % CuO dopant can lower the sintering temperatures dramatically. The second phase of CuTa_2O_6 was found in MgTa_2O_6 ceramics, which caused the deterioration of Q×f value of the ceramics.