Colossal dielectric behavior in TbFeO3 ceramics

TbFeO3(TFO) ceramic samples were prepared via the traditional solid-state reaction route. The low-temperature (100-300 K) dielectric properties of TFO have been systematically investigated in the frequency range from 100 Hz to 5 MHz. Colossal dielectric behavior contributed from two thermally activated dielectric relaxations was found in the sample. The low-temperature relaxation with the activation energy of 0.22 eV was confirmed to be a polaron relaxation caused by electrons hopping between the mixed-valent states of Fe ions. The high-temperature relaxation shows the activation energy of 0.59 eV and can be enhanced by annealing treatment in oxygen and weakened in nitrogen. This relaxation was ascribed to be a Maxwell-Wagner relaxation due to surface-layer effect. (C) 2013 Elsevier B. V. All rights reserved.