Ultralow-fired Li2Mg3TiO6-Ca0.8Sr0.2TiO3 composite ceramics with temperature stable at microwave frequency

New temperature stable 4 wt% LiF-doped (1−x)Li2Mg3TiO6-xCa0.8Sr0.2TiO3 (LMT-CST, x = 0.10, 0.15, 0.20, 0.25) composite ceramics were fabricated by solid-state reaction for developing ultra-low temperature (≤800 °C) sintering microwave dielectric ceramics. Sintering temperatures of LMT-CST ceramics were successfully lowered to 725 °C due to LiF liquid-phase sintering and well-densified microstructures were obtained at 800 °C. Excellent microwave dielectric properties of εr = 18.8, Q × f = 48200 GHz (at 8.2 GHz), τf = 0.3 ppm/°C was obtained at 800 °C for 0.8 LMT-0.2CST-4wt% LiF ceramics. Such sample was compatible with Ag electrodes, which suggests suitability of the developed material for LTCC applications.