Proton Conductivity of Simple Ionic Hydroxides Part II: In Situ Formation of Water Molecules Prior to Dehydration

Abstract

Abstract The formation of transitory HOH species in hydroxide lattices prior to dehydration was studied by thermally stimulated depolarisation, TSDp, and by high temperature infrared spectroscopy. Adsorbed H 2 O give regular TSDp maxima. Protonic space charge clouds, assigned to excess protons H* and defect protons H 1 , give inverted TSDp effects. At the temperature of the maximum of the proton conductivity the charge carrier concentration is of the order of 10 13 mol −1 which corresponds to the expected Boltzmann occupancy in the conduction band. Excess protons H* temporarily trapped from the space charge clouds on lattice OH − sites form H 2 O molecules, visible in the IR spectrum, which redissociate at room temperature.