Ca3ZnAl4O10: A novel Al-rich microwave dielectric ceramic with low-εr

Abstract

Low-εr microwave dielectric ceramics Ca3ZnAl4O10 with orthorhombic structure were fabricated by solid-state reaction process. Good grain uniformity and compact microstructure were observed at 1290 °C. Single phase Ca3ZnAl4O10 ceramics were obtained at the range of 1250–1330 °C and exhibited promising microwave dielectric properties with εr = 8.11–8.31, Q×f = 23,060–30,750 GHz and τf = −27.5 to −23.3 ppm/°C. The larger positive deviations between εtheo and εcorr as well as the smaller |τf∣value could be ascribed to the strong “rattling” effect. The calculated bond valence show that Ca2+, Al3+ are “rattling” cations while Zn2+ is “compressed” cation. Furthermore, the Q×f values is mainly affected by the density and packing fraction.