Preparation and Characterization of Citrate Sol-Gel Derived CaLa₄Ti₄O₁₅ Microwave Dielectric Ceramics

In this work hexagonal perovskite powders of CaLa4Ti4O15 were prepared by citrate sol-gel method. The calcined temperature was 1150oC, which is lower than that of the conventional solid method. Dense CLT ceramics were produced at sintering temperature of 1600oC. The crystal structures and microstructures were investigated by XRD, TEM and SEM, respectively. Compared with samples produced by solid method, the sol-gel derived CLT ceramics exhibited a near zero temperature coefficient of resonant frequency (τf ) of -6 ppm/oC, and other microwave properties , εr ~ 43, Q×f ~ 42000 GHz were also obtained. Moreover, the sintering temperature of the CLT ceramics could be reduced to 1400 oC by addition of B2O3-ZnO.