Preparation and Microwave Dielectric Properties of Ca(Sm_(0.5)Nb_(0.5))O_3 Ceramics

摘要

Microstructures and microwave dielectric properties of Ca(Sm_(0.5)Nb_(0.5))O_3 ceramics, prepared by a conventional solid-state reaction method, were systematically investigated by varying calcining temperature, sintering temperature and cooling rate. The XRD result showed that a single Ca(Sm_(0.5)Nb_(0.5))O_3 phase could be synthesized at a calcining temperature of 1200 °C. Optimized combination of microwave dielectric properties of ε_r = 22.36, Q×f= 18030 GHz and τ_f = -31.2 ppm/°C was obtained for the furnace-cooled Ca(Sm_(0.5)Nb_(0.5))O_3 ceramics sintered at 1550 °C for 4 h. However, some microcracks were found from the microstructures of the furnace-cooled specimens. Further, the Q×f value could be increased by controlling the cooling rate during the sintering process due to the disappearance of microcracks in the final material. With a cooling rate of 2 °C/min, Ca(Sm_(0.5)Nb_(0.5))O_3 ceramics exhibited an enhanced Q×f value of 37130 GHz.