A novel temperature stable and high Q microwave dielectric ceramic in Li3(Mg1−xMnx)2NbO6 system

Abstract

The compositions of Li3(Mg1−xMnx)2NbO6 ceramics were prepared by the conventional solid state reaction method. The effects of Mn2+ substitution on the microstructure, sintering behavior and microwave dielectric properties of Li3(Mg1−xMnx)2NbO6 ceramics were investigated systematically. The XRD patterns revealed that all the specimens sintered at 1075–1200 °C remained a single phase with orthorhombic structure. The obtained microwave dielectric properties indicated that appropriate amount of Mn2+ substitution for Mg2+ could significantly promote the grain growth and densify Li3Mg2NbO6 ceramics. The permittivity and Q × f values were strongly dependent on the bulk density and grain size, respectively. And near zero τ f values could be realized in the Li3(Mg1−xMnx)2NbO6 (0.02 ≦ x ≦ 0.08) compounds sintered at 1125 °C. To sum up, the x = 0.02 sample sintered at 1125 °C for 4 h exhibited excellent microwave dielectric properties of er ~ 15.22, Q × f ~110,582 GHz, τ f ~−4.57 ppm/°C which demonstrated that the Li3(Mg0.98Mn0.02)2NbO6 ceramic would be a novel temperature stable and high Q material for microwave device.