Effect of iron chloride on the polaronic conduction in potassium phosphate glasses containing iron oxide

DC electrical conductivity measurements of Fe2O3-K2O-P2O5 glasses containing iron chloride have been carried out in the temperature range from room temperature to 360"C. The DC conductivity was analyzed in terms of small polaron hopping theory. The hopping regime between Fe ions was confirmed to be nonadiabatic. The increase in the conductivity was of the same order of magnitude as the change in the pre-exponential factor upon increasing the FeCl3 content. The decrease in the activation energy with increasing FeCI3 content was interpreted in terms of a decrease in the distance between the iron sites. The increase in electrical conductivity was ascribed to lhe difference in the activation energy. The variation Ain the conductivity parameters was interpreted in terms of the structural changes that take Aplace upon increasing the FeCl3 content of the glasses.