Microwave dielectric properties of the low-temperature-fired Li₂ZnTi₃O₈–Li₂TiO₃ ceramics for LTCC applications

In this work, 0.73Li₂ZnTi₃O₈–0.27Li₂TiO₃ ceramics were prepared through a traditional solid-state process. The effects of Li₂O–B₂O₃–SiO₂–CaO–Al₂O₃ (LBSCA) glass addition on phase formation, microstructure, sintering characteristic and microwave dielectric properties of the ceramics were investigated. A small amount of LBSCA glass addition significantly reduced sintering temperature of the ceramics. X-ray diffraction analysis revealed that Li₂ZnTi₃O₈ and Li₂TiO₃ phases coexisted without producing any other crystal phases in the sintered ceramics. Dielectric constant and Qf values were related to the amount of LBSCA addition and sintering temperatures. The specimens obtained near-zero temperature coefficient (τ_f) values through the compensation on the positive τ_f of Li₂TiO₃ and the negative τ_f of Li₂ZnTi₃O₈. The 0.73Li₂ZnTi₃O₈–0.27Li₂TiO₃ ceramic with 0.75 wt% LBSCA addition and sintered at 900 °C for 3 h exhibited excellent microwave dielectric properties of ɛ_r = 23.907, Qf = 63050 GHz and τ_f = 1.2 ppm/°C, which was very suitable for LTCC (low temperature co-fired ceramics) applications.