Microstructures and microwave dielectric properties of (1 − y)La1−xSmx(Mg0.5Sn0.5)O3–yCa0.8Sm0.4/3TiO3 ceramics

The (1 − y)La1−xSmx(Mg0.5Sn0.5)O3–yCa0.8Sm0.4/3TiO3 ceramics were prepared by the conventional solid-state method. The X-ray diffraction patterns of the La1−xSmx(Mg0.5Sn0.5)O3 ceramics revealed that La1−xSmx(Mg0.5Sn0.5)O3 is the main crystalline phase, which is accompanied by a little La2Sn2O7 as the second phase. An apparent density of 6.59 g/cm3, a dielectric constant (ɛr) of 19.9, a quality factor (Q × f) of 70,200 GHz, and a temperature coefficient of resonant frequency (τf) of −77 ppm/°C were obtained when the La0.97Sm0.03(Mg0.5Sn0.5)O3 ceramics were sintered at 1500 °C for 4 h. The temperature coefficient of resonant frequency (τf) increased from −77 to +6 ppm/°C as y increased from 0 to 0.6 when the (1 − y)La0.97Sm0.03(Mg0.5Sn0.5)O3–yCa0.8Sm0.4/3TiO3 ceramics were sintered at 1500 °C for 4 h. 0.425La0.97Sm0.03(Mg0.5Sn0.5)O3–0.575Ca0.8Sm0.4/3TiO3 ceramic that was sintered at 1500 °C for 4 h had a τf of −3 ppm/ °C.