Effect of excess lithium on the structure and microwave dielectric properties of LiMg0.5Ti0.5O2 ceramics

Abstract

AbstractHerein, Li1+xMg0.5Ti0.5O2 (0.000 ≤ x ≤ 0.075) ceramics with excess lithium were prepared by solid‐state reaction method to compensate for lithium volatilization, thus optimizing dielectric properties. The second phase Mg2TiO4 decreases with excess lithium content and eventually disappears at x = 0.05. Of these, Li1.0375Mg0.5Ti0.5O2 illustrates the best dielectric properties with εr = 16.58, Q × f = 120712 GHz (@9.18 GHz), and τf = −16.31 ppm/°C. From the point of view of non‐intrinsic factors, excess lithium at optimum ratios slightly facilitates the sintering of the ceramics, improves densification, and increases the grain size, resulting in improved dielectric properties. For intrinsic factors, a slight increase in bond ionicity results in a slight improvement in εr. First‐principles calculations demonstrate that suitable excess lithium increases electron cloud density in the internal space of Li/Mg/TiO6 octahedron and increases band gap, thus optimizing the dielectric properties. The same results were obtained from the perspective of lattice vibrations. The modified Li1.0375Mg0.5Ti0.5O2 ceramics offer great potential for future microwave communication technology.