The abnormal multiple dielectric relaxation responses of Al3+ and Nb5+ co-doped rutile TiO2 ceramics

摘要

Al3+ and Nb5+ co-doped rutile TiO2 ceramic samples were prepared by solid state reaction. Raman spectra, element mapping and EDX confirmed that (Al + Nb) dissolved into grain. The samples showed colossal permittivity (epsilon' approximate to 3.8 x 10(4)) with low dielectric loss (under 0.08) over frequency (20 Hz -100 kHz) and temperature (80 K-240 K) ranges. Abnormal multiple dielectric relaxation properties were obtained around 5 K. Using universal relaxation law and thermal polaron hopping, we concluded that high dielectric constant of (Al1/2Nb1/2)(0.05)Ti0.95O2 was due to thermal activation of electrons in defect-dipoles, polaron hopping polarization and interfacial polarization. This investigation could increase our understanding models of multiple dielectric relaxation and inhomogeneous composition in co-doped rutile TiO2. (C) 2020 Elsevier B.V. All rights reserved.