Effects of defect dipoles on the colossal permittivity of ambipolar co-doped rutile TiO ceramics

Abstract

This study investigated the colossal permittivity of ambipolar co-doped rutile TiO2 ceramics obtained using the solid state sintering method for use as alternatives to high-performance dielectric materials. Ambipolar co-doping was conducted with compositions comprising Ti0:995ðNb1:33ðAl1 xCrxÞ0:666Þ0:005O2, where x ¼ 0, 0.3, 0.5, 0.7, 0.9, and 1. Analysis based on X-ray diffraction, Fourier transform-infrared spectroscopy, and Raman spectra showed that the dopants did not alter the crystal structure of rutile but they created some distortion in the TiO2 lattice. Analysis of the dielectric properties showed that the ceramics exhibited relatively low loss with colossal permittivity at room temperature. The existence of an asymmetrical relaxation mechanism was demonstrated with the Fuoss–Kirkwood dielectric model. The combined functions of defect dipoles and localized electrons were investigated for ambipolar co-doped TiO2 ceramics for use in high-density RAM and microelectronics applications.