Effect of Sb-site nonstoichiometry on the structure and microwave dielectric properties of Li3Mg2Sb1-xO6ceramics

The 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 Li(3)Mg(2)Sb(1-x)O(6)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 Li(3)Mg(2)SbO(6)was formed in all compositions. Appropriate Sb-deficiency in Li(3)Mg(2)SbO(6)not only lowered its sintering temperature but also remarkably improved itsQxfvalue. In particular, non-stoichiometric Li(3)Mg(2)Sb(0.9)O(6)ceramics sintered at 1250 degrees C/5 h owned seldom low dielectric constant epsilon(r)= 10.8, near-zero resonant frequency temperature coefficient tau(f)= -8.0 ppm/degrees C, and high quality factorQxf= 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.