Abstract
The effects of the sintering temperature on microstructures, electrical properties, and dielectric response of 1%Cr3+/Ta5+ co-doped TiO2 (CrTTO) ceramics prepared using a solid-state reaction method were studied. The mean grain size increased with an increasing sintering temperature range of 1300-1500 degrees C. The dielectric permittivity of CrTTO ceramics sintered at 1300 degrees C was very low (epsilon' similar to 198). Interestingly, a low loss tangent (tan delta similar to 0.03-0.06) and high epsilon' ( similar to 1.61 1.9 X 10(4)) with a temperature coefficient less than <= +/- 15% in a temperature range of -60 to 150 degrees C were obtained. The results demonstrated a higher performance property of the acceptor Cr3+/donor Ta5+ co-doped TiO2 ceramics compared to the Ta5+ -doped TiO2 and Cr3+- doped TiO2 ceramics. According to a first-principles study, high-performance giant dielectric properties (HPDPs) did not originate from electron-pinned defect dipoles. By impedance spectroscopy (IS), it was suggested that the giant dielectric response was induced by interfacial polarization at the internal interfaces rather than by the formation of complex defect dipoles. X-ray photoelectron spectroscopy (XPS) results confirmed the existence of Ti3+, resulting in the formation of semiconducting parts in the bulk ceramics. Low tan delta and excellent temperature stability were due to the high resistance of the insulating layers with a very high potential barrier of similar to 2.0 eV.
