Microwave dielectric properties of CaWO4–Li2TiO3 ceramics added with LBSCA glass for LTCC applications

In this work, 0.86CaWO4–0.14Li2TiO3 ceramics were prepared via a traditional solid-state process. The effects of Li2O–B2O3–SiO2–CaO–Al2O3 (LBSCA) addition on the phase formation, sintering character, microstructure and microwave dielectric properties of the ceramics were investigated. A small amount of LBSCA addition could effectively lower the sintering temperature of the ceramics. X-ray diffraction analysis revealed that CaWO4 and Li2TiO3 phases coexisted without producing any other crystal phases in the sintered ceramics. The dielectric constant and Qf values were related to the amount of LBSCA addition and sintering temperatures. All specimens could obtain near-zero temperature coefficient (τf) values through the compensation of the positive τf of Li2TiO3 and the negative τf of CaWO4. The 0.86CaWO4–0.14Li2TiO3 ceramic with 0.5 wt% LBSCA addition and sintered at 900 °C for 3 h exhibited excellent microwave dielectric properties of εr=12.43, Qf=76,000 GHz and τf=−2.9 ppm/°C.