The phase evolution, microstructure and microwave dielectric properties of non-stoichiometric Li_2(1+x)Mg₃TiO₆ ceramics

An efficient reaction sintering process is engaged to synthesize a series of non-stoichiometric Li_2(1+x)Mg₃TiO₆ (x = 0.01, 0.02, 0.03, 0.04) microwave dielectric ceramics. The single phase of Li₂Mg₃TiO₆ with rock-salt structure is accurately recognized by XRD. Pores left on the surface and inside the sample can be clearly observed from SEM pictures. Excessive Li⁺ affects the local charge distribution, which influences the response of the dielectric material to the electric field. The pores are not the same medium as the matrix material, and the signal is refracted and scattered when it passes through the pores. Refractions and scatterings increase the signal transmission distance and also increase the transmission loss. These residual Li⁺ and pores eventually affect the dielectric properties as well. Finally, at x = 0.02 and a sintering temperature of 1260 °C, the ceramic samples showed good dielectric properties: ε_r = 10.983, Q×f = 107,367 GHz and τ_f = − 24.2 ppm/°C.