Correlation between structure characteristics and dielectric properties of Li2Mg3-xCuxTiO6 ceramics based on complex chemical bond theory

A series of Li2Mg3-xCuxTiO6 (x = 0.00-0.20) ceramics were synthesized by a simple solid-state reaction. The influences of Cu2+ substitution on the microwave dielectric characteristics, structure characteristics and morphology of Li2Mg3TiO6 ceramics were investigated. The XRD results demonstrated that all samples displayed the pure Li2Mg3TiO6 phase with rock salt structure. The SEM results exhibited that a microstructure evolution from porous structure to nearly compact structure appeared with increasing Cu2+ content, indicating that the pores originated from lithium volatilization could be suppressed by Cu2+ substitution. Subsequently, the dependence of microwave dielectric properties on intrinsic factors was evaluated based on refinement results and P-V-L theory. The monotonic increase of dielectric constant (epsilon(r)) was mainly correlated with the polarizability. The variation of quality factor (Q x f) was dependent on the total systematic lattice energy and packing fraction. In addition, the evolution tendency of the temperature coefficient of resonant frequency (tau f) was explained by the linear thermal expansion coefficient alpha and EMg/Cu-O bond energy. All results suggested that the intrinsic factors play decisive roles on dielectric characteristics.