Crystals with disordered hydrogen-bond networks and superprotonic conductivity. Review

The class of hydrogen-containing salts in which the phases with dynamically disordered hydrogen-bond nets are formed has been considered. Unlike other hydrogen-bonded crystals, the crystals of this class are characterized by delocalized hydrogen bonds producing considerable influence on their physical and physical-chemical properties. The structural transitions between the phases with ordered and disordered hydrogen-bond networks are described with the emphasis being made on the structural mechanisms of anomalously high (superprotonic) conductivity associated with delocalization of hydrogen bonds. The perspectives of the use of crystals with delocalized hydrogen bonds in fuel cells and other electrochemical devices are discussed.