Microwave dielectric properties of high dielectric tunable - low permittivity Ba_(0.5)Sr_(0.5)TiO_3-Mg_2(Ti_(0.95)Sn_(0.05))O_4 composite ceramics

摘要

Ba_(0.5)Sr_(0.5)TiO_3-Mg_2(Ti_(0.95)Sn_(0.05))O_4 composite ceramics have been synthesized by the solid-state reaction. Phase structure, microstructure and microwave dielectric properties have been systematically characterized. The permittivity is tailored to a certain extent with the addition of Mg_2(Ti_(0.95)Sn_(0.05))O_4. Both X-ray diffraction (XRD) and back electric image (BEI) analysis show the co-existence of two-phase structures of ABO_3 perovskite and A_2BO_4 spinel structure. A high dielectric tunablity can be obtained and a high Q value can be achieved at microwave frequency. The composition 30 wt.%Ba_(0.5)Sr_(0.5)TiO_3-70 wt.%Mg_2(Ti_(0.95)Sn_(0.05))O_4 exhibits good dielectric properties with e of 79, Q of 152 (at 2.997 GHz) and T of 15.8% (30 kV/cm & 10 kHz) at room temperature, which make it a promising candidate for tunable microwave device applications in the wireless communication system.