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New superprotonic crystals with dynamically disordered hydrogen bonds: cation replacements as the alternative to temperature increase

ABSTRACT: The single-crystal structure of [K0.43(NH4)0.57]3H(SO4)2 has been determined using X-ray diffraction; its dielectric properties have been studied to define the structural influence on the abnormal physical properties. Investigations of new single crystals grown in the K3H(SO4)2–(NH4)3H(SO4)2–H2O system from solutions with different K:NH4 concentration ratios have been carried out. Based on the X-ray diffraction data, the atomic structure of the crystals was determined at room temperature taking H atoms into account. It has been determined that [K0.43(NH4)0.57]3H(SO4)2 crystals are trigonal at ambient conditions such as the superprotonic phase of (NH4)3H(SO4)2 at high temperature. A distribution of the K and N atoms in the crystal was modelled on the basis of the refined occupancies of K/N positions. Studies of dielectric properties over the temperature range 223–353?K revealed high values of conductivity of the crystals comparable with the conductivity of known superprotonic compounds at high temperatures, and an anomaly corresponding to a transition to the phase with low conductivity upon cooling.

SUBMITTER: Selezneva E

PROVIDER: S-EPMC5744412 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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