Preparation, structural and microwave dielectric properties of CaLa4(ZrxTi1−x)4O15 ceramics

Hexagonal-phase CaLa4(ZrxTi1−x)4O15 (x = 0.01-0.1) with excellent microwave dielectric properties are candidate materials for microwave dielectric resonators. An excess of Zr4+ resulted in the formation of a secondary phase of CaLa4Ti5O17, affecting the microwave dielectric properties of the CaLa4(ZrxTi1−x)4O15 ceramics. By increasing x from 0.01 to 0.05, the dielectric constant and Q × f value of the specimen could be increased from 45.8 to a maximum of 46, and from 44,800 GHz to a maximum of 47,500 GHz at a sintering temperature of 1550 °C, respectively. The zero temperature coefficient of the resonant frequency of the CaLa4(ZrxTi1−x)4O15 ceramics also improved with increasing Zr content.