The effect of sintering atmosphere on colossal permittivity in W+Mg/Al co-doped TiO2 ceramics

Abstract The effects of sintering atmosphere on the dielectric behaviors of W+Mg/Al co-doped rutile TiO2 ceramics are investigated. The samples fabricated in N2 atmosphere show a colossal permittivity (CP) while the relative dielectric constant er deteriorates distinctly for those sintered ceramics in air. For example, a CP with er ~2.6 × 105 and a small dielectric loss (~0.062) are obtained at 10 kHz for nitrogen atmosphere sintered (W0.5Mg0.5)0.005Ti0.995O2. The dielectric permittivity has only 110 at 10 kHz for the air atmosphere sintered sample with the same composition. Moreover, the dielectric properties as a function of temperature are measured from room temperature (~25 °C) to 450 °C. In accordance with the analysis of XPS and impedance spectroscopy, the main contribution for the CP property in our sample stems from the semi-conductive grain and highly insulating grain boundary which result in the strong interface polarization for the N2 sintered samples. The experimental results in our work can enrich the TiO2-based CP system.