Temperature-stable and ultralow-loss (1-x)CaSmAlO4-xSr2TiO4 microwave dielectric solid-solution ceramics

The (1 - x)CaSmAlO4-xSr(2)TiO(4) (0.01 <= x <= 0.06) microwave dielectric ceramics were for the first time prepared by a conventional solid-state method. The phase composition, sintering behavior, microstructure and microwave dielectric properties were investigated as function of sintering temperature and composition. A single-phase solid solution with K2NiF4-type tetragonal structure was formed in the range of 0.02 <= x <= 0.06. All samples are well densified with very little pores. The addition Sr2TiO4 greatly improves dielectric properties originally by restraining the secondary phase and then deteriorates Q x f value because of decreasing tolerance factor. Moreover, the tau(f) value dominated by the thermal expansion coefficient increases lineally as x rises. Finally, excellent microwave dielectric properties of epsilon(r) similar to 18.1, Q x f similar to 140,433 GHz (8.5 GHz), and a near-zero tau(f) similar to + 0.05 ppm/degrees C can be obtained in the x = 0.05 ceramic sintered at 1425 degrees C.