Raman spectroscopy, chemical bonding, and microwave dielectric properties of Li4AlSbO6 ceramics

A novel Li4AlSbO6 (LASO) microwave dielectric ceramic with a monoclinic structure and space group C12/c1 was successfully prepared using traditional solid-state methods. When the sintering temperature was 1200 °C, it had excellent microwave dielectric properties, with εr = 8.2, Q × f = 22,098 GHz, and τf = −15.53 ppm/°C. Raman spectroscopy analysis showed that the FWHM of the strong peak at 691cm−1 reflected the variation trend of Q × f value and was opposite to the variation trend of Q × f value. Additionally, the augmentation in the Q × f value can be attributed to a higher relative density. As per the bond valence analysis, εr is closely connected to the rattling and compressing effects of A-site cations, and the higher εtheo than εr in Li4AlSbO6 can be attributed to the strong compression effect induced by Li+. Additionally, τf may be influenced by both the Sb–O bond and relative density.