Ageing exploration of the energy landscape of a glass by the TSDC technique

Abstract

Different thermal treatments were used in order to follow the structural relaxation of m-toluidine by thermally stimulated depolarization currents (TSDC) in the sub-T g temperature region. In some of these thermal treatments, the ageing time, t a, and the probing (or polarization) time, t P, are varied independently in order to allow a clear understanding of the exploration of the energy landscape which occurs as a consequence of the structural relaxation. The TSDC results show that ageing induces a shift to higher temperatures of the TSDC peaks, in a way similar to that observed in the calorimetric heat capacity overshoot. More importantly, TSDC results show that ageing induces a decrease of the activation energies with regard to the window defined by the probing time and a sharpening of the energy distribution of the modes of motion that are present in the glass, in the studied sub-T g temperature region.