The effects of ZnO doping on microstructure and microwave dielectric properties of Li3Mg2TaO6 ceramics with rock salt structure

摘要

In this study, the ZnO doping Li3Mg2TaO6 were prepared by solid state reaction method. The correlations between microstructure and microwave dielectric characterizations of Li3Mg_(2-x)ZnxTaO6(x=0-0.5) ceramics were systematically investigated. All the samples showed the single phase of Li3Mg2TaO6 with orthorhombic structure in Fddd (70) space group, and the structure refinement results showed the increase of the cell volume with the increasing x. The SEM images indicated that the dense structures were obtained in the range of 0-0.3, and a small amount of ZnO impurity phase was observed in grain boundaries because of the evaporation of ZnO in the high sintering temperature. The εr and τf increased as the ZnO content increased. The Q×f value increase firstly with the increasing x, to the maximum at x=0.3, and then decreased. As sintered at 1270 °C for 4h, the Li3Mg_(1.7)Zn_(0.3)TaO6 (x=0.3) ceramics showed the excellent microwave properties: εr= 20.61, Q×f= 106,863 GHz and τf = -21.6ppm/°C.