Scaling properties of thermally stimulated currents in disordered systems

We investigate the non-isothermal manifestation of Jonscher's universal dynamic response in terms of thermally stimulated depolarization (TSD) currents. We show that relaxation processes which display power-law behavior and which obey in addition the time-temperature superposition principle are adequately described by a new TSD scheme which consists of a fractional power of the reduced time. The initial current of TSD peaks in disordered materials such as ionically conducting glasses, polymers, and amorphous semiconductors, is. found to exhibit two major aspects of remarkable generality: a dependence on heating rate (which is unpaired in the classical model), and an effective activation energy with a value of aE, where E is the activation energy for the scaling time and a is a fractional exponent. The underlying link between these results and the self-scaling property of the relaxation function is pointed out. (C) 1999 Elsevier Science B.V. All rights reserved.