Electronic and ionic conductivity of glasses inside the Li2O-MoO3-P2O5 system

A wide range of coloured electronic or mixed electronic-ionic glasses has been shown in the alkali oxide poor-region of the Li2O-MoO3-P2O5 system, next to the colourless ionic glasses located in the alkali oxide rich-region. These coloured glasses have been studied by electron paramagnetic resonance (EPR) spectroscopy. The Mo5+ and Mo6+ cation percentages have been evaluated for several series of glasses corresponding to either a fixed Li2O rate or a constant Mo/P ratio. The electronic and the ionic contributions to the total conductivity of these glasses have been determined. The existence of a polaronic hopping conduction mechanism between Mo5+ and Mo6+ cations is suggested in the purely electronic conductor glasses. An ion-polaron soft coupling is proposed in the ionic-electronic conductor glasses. (C) 2000 Elsevier Science B.V. All rights reserved.