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

Abstract Herein, Li 1+ x Mg 0.5 Ti 0.5 O 2 (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 Mg 2 TiO 4 decreases with excess lithium content and eventually disappears at x = 0.05. Of these, Li 1.0375 Mg 0.5 Ti 0.5 O 2 illustrates the best dielectric properties with ε r = 16.58, Q × f = 120712 GHz (@9.18 GHz), and τ f = −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 ε r . First‐principles calculations demonstrate that suitable excess lithium increases electron cloud density in the internal space of Li/Mg/TiO 6 octahedron and increases band gap, thus optimizing the dielectric properties. The same results were obtained from the perspective of lattice vibrations. The modified Li 1.0375 Mg 0.5 Ti 0.5 O 2 ceramics offer great potential for future microwave communication technology.