Effect of Sb-site nonstoichiometry on the structure and microwave dielectric properties of Li3Mg2Sb1−xO6 ceramics

Abstract The non-stoichiometric Li₃Mg₂Sb_1−xO₆(0.05 ⩽x⩽ 0.125) compounds have been prepared via the mixed oxide method. The influences of Sb nonstoichiometry on the sintering behavior, microstructure, phase composition along with microwave dielectric performances for Li₃Mg₂Sb_1−xO₆ceramics were studied. Combined with X-ray diffraction (XRD) and Raman spectra, it was confirmed that phase composition could not be affected by the Sb nonstoichiometry and almost pure phase Li₃Mg₂SbO₆was formed in all compositions. Appropriate Sb-deficiency in Li₃Mg₂SbO₆not only lowered its sintering temperature but also remarkably improved itsQ×fvalue. In particular, non-stoichiometric Li₃Mg₂Sb_0.9O₆ceramics sintered at 1250 °C/5 h owned seldom low dielectric constantε_r= 10.8, near-zero resonant frequency temperature coefficientτ_f= −8.0 ppm/°C, and high quality factorQ×f= 86,300 GHz (at 10.4 GHz). This study provides an alternative approach to ameliorate its dielectric performances for Li₃Mg₂SbO₆-based compounds through defect-engineering.