Analysis of thermally stimulated currents

While thermally stimulated depolarization currents, sometimes in conjunction with the thermal slicing technique, are often used to determine the activation energies and relaxation times of the processes occurring in a material, little attention has been paid to the question of whether the results do represent the true properties of the system. In this paper, a theoretical analysis and the results of calculations are presented for systems whose isothermal behaviour can be described in terms of a distribution of relaxation times (DRT). It is found that for a DRT with a common activation energy E₀, the activation energy E_BO derived from the Bucci or BFG relaxation time is often less than E₀, white if the DRT is associated with a distribution of activation energies the prefactor of the BFG relaxation time often differs from its true value. Simple criteria are proposed for establishing whether the parameters derived from any given set of measurements do in fact correspond to those of the system, and for distinguishing between a DRT with a distribution of activation energies and one with a single activation energy.