Investigation of titanium oxide additive on the microstructure and dielectric properties of zinc oxide

Zinc oxide (ZnO) is widely used in various fields such as electronic devices, converters, varistors, catalysts, photoelectric devices, and piezoelectric application due to its unique properties. In the present study, the effect of titanium oxide (TiO2) additive on the properties of ZnO ceramic was studied. 0.5, 1 and 2 wt% of TiO2 were added to ZnO and various properties of ZnO ceramic including density, phase behavior, dielectric properties and microstructure were investigated. The obtained samples had a high relative density and about 98% of the theoretical density. The results of X-ray diffraction (XRD) showed that TiO2 additive leads to the formation of a secondary phase of Zn2TiO4 in ZnO ceramic and with increasing the amount of TiO2, the amount of impurity phase increases and the peaks move to lower angles. TiO2 additive considerably reduced the dielectric constant and the dielectric loss of ZnO ceramic. With addition of 2 wt% TiO2, the dielectric constant of ZnO was decreased from 48200 to 1400 and the dielectric loss of ZnO was decreased from 20 to 5.4, measured at 100 kHz. The results of microstructure study showed that TiO2 additive will have a significant effect on the microstructure of ZnO ceramic, so that with increasing the amount of TiO2 additive, grain growth decreases. The reduction in the constant dielectric of ZnO ceramic can be attributed to the smaller grain size, the existence of the impurity phase and the defect of the cation vacancy in the presence of TiO2 additive.