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

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.

Automated summary

Al3+ and Nb5+ co-doped rutile TiO2 ceramic samples were prepared by solid state reaction, showing colossal permittivity with abnormal multiple dielectric relaxation properties. The high dielectric constant is attributed to thermal activation of electrons, polaron hopping polarization, and interfacial polarization.