PROTON-PHONON INTERACTION AND POLARON MASS IN ABO₃ PEROVSKITES

Abstract

The motivation of the present paper lies in some recent experimental and first-principles studies of the phonon-aided long-range proton transfer in solid oxides. We extend the results of our previous papers in order to provide theoretical underpinnings for these evidences. A model for the underlying mechanism of the phonon-assisted proton hopping is considered. A new concept of the Euclidean time relevant to proton conductors is introduced.  The model is able to explain how the hopping rate depends on the resonant infrared light that selectively excites the O-H stretch mode and would affect both the activation energy barrier and effective mass for proton polarons. Those Holstein type polarons, which are fundamental objects of condensed matter physics, are also found interesting from the perspective of new designs of energy devices like fuel cells, called here phonon-assisted fuel cells.