Preparation and characterization of LaSrAlO4 microwave dielectric ceramics

LaSrAlO4 ceramics with K2NiF4 structure were prepared by a conventional solid state sintering process, and their microstructures and microwave dielectric properties were investigated. Dense ceramics were obtained by sintering at the temperatures of 1375–1450 °C in air. The dielectric constant was 15.3–17.1, and the Qf value varied from 28,760 to 32,820 GHz under different sintering temperature. The temperature coefficient of resonant frequency varied from negative to positive with increasing sintering temperature. The best microwave properties were obtained for the present ceramics sintered at 1450 °C for 3 h: ε=17.1, Qf=30,770 GHz and τf=3.4 ppm/°C.