Flash Sintering Preparation and Characterizations of (M0.5Ta0.5)0.05Ti0.95O2 (M = Al, Ga, In) Colossal Dielectric Ceramics

In this paper, (M0.5Ta0.5)(0.05)Ti0.95O2 (M = Al, Ga, In) ceramic materials were successfully prepared by Flash Sintering (FS) under an electric field of 550 V cm(-1) at 1200 degrees C for 18 min. The influences of different ionic radius on flash sintering behavior, crystal structure, microstructure and dielectric properties of TiO2-based colossal permittivity (CP) ceramics were systematically investigated. FS can reduce the sintering temperature by 200 degrees C and shorten the sintering time by more than 12 times. The results show that all flash sintering samples were pure rutile TiO2 structure. The grain size decreased with increasing ionic radius. ATTO had the lowest dielectric loss of 0.2 and ITTO had a maximum dielectric constant of 8100 at 1 kHz. XPS analysis confirms that Ti3+ content increased gradually with increasing ion radius. Impedance spectroscopy analysis shows that all flash sintering ceramics were composed of semi-conductive grains and insulating grain boundaries. The CP behavior was explained using the internal barrier layer capacitance effect. This work provides a very meaningful method for the preparation of co-doped TiO2 CP ceramic materials.