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 selenates is analysed. The latest X-ray diffraction investigations of these compounds show that a highly correlated dynamic disorder of the hydrogen bonds occurs in the superionic phases. The observed diffraction patterns result from dynamically twinned crystals, which consist of a symmetry-related number of domains. We discuss the ‘anomalous display of the dynamically disordered hydrogen atoms on the electron density maps’, which is observed in the superionic phases. New X-ray diffraction data allow the atomic level mechanism of proton transport in the alkali metal hydrogen sulfates and selenates to be elucidated in detail.