Structural evolution and microwave dielectric properties of Ca-substituted ZnTiTa2O8 ceramics with medium permittivity

In this study, Zn1-xCaxTiTa2O8 (x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10) ceramics were sintered from 1225 °C to 1325 °C via the solid-state reaction route. A mixture of trirutile and ixiolite phases was confirmed by the XRD and Raman spectra. The ratio of these two phases was determined by x, which was also a critical impact factor for the microwave dielectric properties. It was noticed that the × f value increased to a maximum at x = 0.02, then deteriorated gradually with further increases of x. The improved permittivity value with x was attributed to the higher polarizability of Ca2+ than that of Zn2+. Optimal microwave dielectric performance was observed in the Zn0.98Ca0.02TiTa2O8 ceramics sintered at 1250 °C: εr= 36.5, × f= 73,865 GHz, and τf= 14 ppm/°C. The experimental results suggest that the Ca-modified ZnTiTa2O8 ceramics are promising for miniaturized microwave device applications.