Microwave dielectric properties of LiMVO₄ (M=Mg, Zn) ceramics with low sintering temperatures

Microwave dielectric ceramics LiMVO₄ (M=Mg, Zn) were prepared by using the solid state reaction method. Microstructure and microwave dielectric properties of the ceramics were investigated. The LiMgVO₄ ceramic could be well densified at 675 °C for 2 h and exhibited good microwave dielectric properties with a relative permittivity of 9.1, a Q×f value of 33,730 GHz and τ_f value of -160 ppm/°C. Meanwhile, the LiZnVO₄ ceramic sintered at 750 °C for 2 h with excellent microwave dielectric properties, i.e., a relative permittivity of 7.6, a Q×f value of 22,000 GHz and τ_f value of -110 ppm/°C. X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS) results indicated that very small part of LiMgVO₄ phase and LiZnVO₄ phase reacted with Ag. Furthermore, the (1-x)LiMVO₄-xTiO₂ (M=Mg, Zn; x=0.20-0.45) ceramics could be sintered at low sintering temperatures (640-760 °C) for 2 h, with relative permittivities of 9.7-20.1, Q×f values of 20,100-39,200 GHz and near zero τ_f values of -20 to 5 ppm/°C.