Lattice structure and microwave dielectric properties of La[Al1−x(Mg0.5Ti0.5)x]O3 (x = 0‐0.2)‐based ceramics

Abstract

AbstractLa[Al1−x(Mg0.5Ti0.5)x]O3 (LAMT, x = 0‐0.2) ceramics were synthesized by the conventional solid‐state reaction method and formed a solid solution. The pure solid solutions were recorded by X‐ray diffraction (XRD) in every range. Relative permittivity (εr) and structural stability were greatly affected because the Al3+ site was replaced by [Mg0.5Ti0.5]3+. The total ionic polarizability gradually increased with x, and εr gradually increased. The trend of τf is due to the change in structural stability. The variation in Q × f value increased firstly and then decreased due to the change in the symmetric stretching mode of Al/MgTi–O. The optimum microwave dielectric properties of LAMT were obtained at x of 0.1 after sintering at 1650°C for 5 hours, and εr = 24.9, Q × f = 79 956 GHz, and τf = −33 ppm/°C. The CaTiO3 have a large positive τf (+800 ppm/°C), thus, the τf achieved near zero when CaTiO3 and LAMT (x = 0.1) ceramics were mixed with a certain molar mass, and the optimum microwave dielectric properties of 0.65CaTiO3–0.35LaAl0.9(Mg0.5Ti0.5)0.1O3 were as follows: εr = 44.6, Q × f = 32 057 GHz, and τf = +2 ppm/°C.