Origin of high dielectric permittivity and low dielectric loss of Sr0.985Ce0.01TiO3 ceramics under different sintering atmospheres

The effect of sintering atmosphere on the microstructure and dielectric properties of Sr 0.985 Ce 0.01 TiO 3 were investigated in this article. The sample sintered in nitrogen achieves a colossal permittivity (∼12655) and ultralow dielectric loss (0.006) at room temperature and 1k Hz. XRD results reveal that all the samples belong to P m 3 ¯ m $Pm\overline{3}m$ space group and no secondary phase is detected. It can be verified by XPS measurement that the nitrogen sintered sample has the highest Ti 3+ content. Five dielectric relaxations can be observed in the dielectric spectroscopy in the test temperature range from −130–500 °C, which can be attributed to the existence of Ti 3+ ions, oxygen vacancies and the other associated defect clusters. Moreover, the off-center Ti 3+ ions make a certain contribution to the high permittivity. The ultralow dielectric loss at room temperature could be ascribed to the formation of defect clusters in the samples sintered in air and nitrogen. These defect clusters which associated with the oxygen vacancy, such as T i 3 + − V O .. − T i 3 + $T{i}^{3+}-V_O^{\mathrm{..}}-T{i}^{3+}$ and V S r " − V O ¨ $V_{Sr}^{"}-V_{\ddot{O}}$ are able to localize charge carriers and restrain the motion and ionization of oxygen vacancies.