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

Abstract

AbstractThe non-stoichiometric Li3Mg2Sb1−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 Li3Mg2Sb1−xO6 ceramics 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 Li3Mg2SbO6 was formed in all compositions. Appropriate Sb-deficiency in Li3Mg2SbO6 not only lowered its sintering temperature but also remarkably improved its Q×f value. In particular, non-stoichiometric Li3Mg2Sb0.9O6 ceramics sintered at 1250 °C/5 h owned seldom low dielectric constant εr = 10.8, near-zero resonant frequency temperature coefficient τf = −8.0 ppm/°C, and high quality factor Q×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.