Atomic level mechanism of proton transport in alkali metal hydrogen sulfate and selenate superionic conductors

The mechanism of proton diffusion in alkali metal hydrogen sulfates and sel enates is analysed. The latest X-ray diffraction investigations of these co mpounds show that a highly correlated dynamic disorder of the hydrogen bond s occurs in the superionic phases. The observed diffraction patterns result from dynamically twinned crystals, which consist of a symmetry-related num ber of domains. We discuss the 'anomalous display of the dynamically disord ered hydrogen atoms on the electron density maps', which is observed in the superionic phases. New X-ray diffraction data allow the atomic level mecha nism of proton transport in the alkali metal hydrogen sulfates and selenate s to be elucidated in detail. (C) 2000 Elsevier Science B.V. All rights res erved.