Effect of ZnO additive on microstructure and microwave dielectric properties of CaTi1-x(Fe0.5Nb0.5)(x)O-3 ceramics

The microwave dielectric properties of the CaTi1-x(Fe0.5Nb0.5)(x)O-3 (0.4 less than or equal to x less than or equal to 0.7) solid solutions and the influence of 1 wt% ZnO as a sintering additive are investigated. With the increase of x, dielectric constant (epsilon(r)) and product of quality factor and frequency (Q . f) decrease. The temperature coefficient of resonant frequency (tau(f)) value of nearly Oppm/degrees C can be realized for x = 0.54. The properties of this material are: epsilon(r) = 59.9, Q . f = 3870 GHz. ZnO forms a liquid phase on the grain boundaries and improves the sinterability and grain growth. The correlation between average grain size and Q-factor is observed for ZnO-doped ceramics.