Microwave dielectric properties and low sintering temperature of Ba_(0.5)Sr_(0.5)TiO_3-Mg_2TiO_4 composites synthesized in situ by the hydrothermal method

摘要

(1-x)Ba_(0.5)Sr_(0.5)TiO_3-xMg_2TiO_4 composite? ceramics were synthesized in situ by the hydrothermal method and their structure and dielectric properties were investigated systematically. Results showed that a ferroelectric-dielectric composite containing Ba_(0.5)Sr_(0.5)TiO_3 and Mg_2TiO_4 phases could be successfully synthesized at sintering temperatures below 1300 °C. As the sintering temperature increased, the dielectric peaks of the cubic-tetragonal phase transition were markedly enhanced and sharpened and shifted toward high temperature. As the concentration of Mg_2TiO_4 increased, both permittivity (ε) and tunability (I) decreased, whereas Q value firstly increased and then decreased. The sample with x=0.6 exhibited good microwave dielectric properties, with e of 136, Q of 342 (at 3.804 GHz) and T of 16.2%, which make it a potential candidate for the fabrication of tunable microwave devices.