Flash sintering preparation and colossal dielectric origin of (Al0.5Ta0.5)0.05Ti0.95O2 ceramics

In this paper, (Al, Ta) co-doped TiO2 (ATTO) ceramics were successfully prepared by flash sintering method under different electric fields (450–650 V/cm). The effects of electric field on flash sintering behavior, phase structure, microstructure, dielectric properties and varistor properties of ATTO ceramics were systematically studied. The results showed that all flash sintering ATTO ceramics were single rutile structure. With increasing electric field, grain size gradually increased. When the electric field was 550 V/cm, ATTO ceramic had the best comprehensive performance with dielectric constant of approximately 1.7 × 104, dielectric loss of about 0.5 at 1 kHz, and nonlinear coefficient of 3.5. X-ray photoelectron spectroscopy (XPS) and Impedance spectra (IS) results showed that the origin of good dielectric property was attributed to the internal barrier layer capacitance effect. Therefore, this work is not only of great significance to the further study of co-doped TiO2 colossal dielectric ceramics, but also offers an excellent method for the preparation of capacitive varistor dual-function ceramics.