AC conductivity of amorphous Fe₂O₃-Bi₃O₃ oxide glasses

Abstract

The frequency-dependent ac conductivity of an iron-bismuth semiconducting ferrite glass in the frequency range of 10²-10⁵ Hz and in the temperature range of 77 to 450 K is reported. The experimental data have been analysed with reference to various theoretical models based on the quantum mechanical tunneling through the barrier and the classical hopping over the barrier. The analysis shows that the correlated barrier hopping (CBH) model is the most appropriate one for the present semiconducting glasses. This model predicts quantitatively the temperature dependences of both the ac conductivity and its frequency exponent. However, the other existing theoretical models, such as quantum mechanical tunneling (QMT) and the overlapping large polaron tunneling (OLPT) model, are not consistent with the experimental data.