New rock salt structure dielectric material Li₂Ni₃TiO₆ at microwave frequency

A novel microwave dielectric ceramic Li₂Ni₃TiO₆ with cubic rock salt structure was prepared by the conventional solid-state method. The relationships among sintering behavior, microstructure and microwave dielectric properties for Li₂Ni₃TiO₆ ceramics were investigated. The Li₂Ni₃TiO₆ ceramics sintered at 1275 °C exhibited good microwave dielectric properties of ɛ _r = 13.18, Q f = 9800 GHz, and τ _f = −7.31 ppm/°C. Moreover, Rietveld refinement was used to analyze the crystal structure and the lattice parameters were obtained. Based on the complex chemical bond theory and lattice parameters, the intrinsic factors that influenced the microwave dielectric properties such as the bond ionicity, lattice energy, bond energy and coefficient of thermal expansion were calculated. The ε _r was mainly affected by the bond ionicity of the Ti–O bond. The Q·ƒ was dependent on the lattice energy of Ti–O bond to a certain degree. As for the τ _f , it was mainly influenced by the coefficient of thermal expansion of Li–O bond.