Non-Arrhenius temperature dependence of conductivities in amorphous systems

Abstract

A scheme using the concepts of serial and parallel resistors has been introduced to describe the bent-Arrhenius temperature dependence of electrical conductivities for amorphous systems such as polymer electrolytes and granular metal conduc-tors. It was found that the ionic transport in the former may be characterized by holes jumping in the direction opposite to ionic motion and the electronic current in the latter is featured by the multiple hopping passages. If each jumping step is considered as a micro resistor obeying Arrhenius temperature dependence exp (–E/T), the overall resistance of jumping holes is evaluated by adding the micro resistors in series to generate convex-bent Arrhenius curves such as given by exp [–Q/(T- T_o)], while the conductance of hopping electrons may be calculated by the micro resistors in parallel to produce concave-bent Arrhenius curves such as exp(-Q/T^1/2).