Conductivity, its anisotropy and changes as a manifestation of the features of the atomic and real structures of superprotonic [K 1-x (NH 4 ) x ] 3 H(SO 4 ) 2 crystals.

Single crystals of [K 1-x (NH 4 ) x ] 3 H(SO 4 ) 2 (x ≥ 0.57) grown in the K 3 H(SO 4 ) 2 -(NH 4 ) 3 H(SO 4 ) 2 -H 2 O water-salt system are studied. The atomic structure including H atoms was determined at room temperature using X-ray structural analysis. [K 1-x (NH 4 ) x ] 3 H(SO 4 ) 2 (x ≥ 0.57) crystals have trigonal symmetry and disordered hydrogen-bond networks at ambient conditions similar to the high-temperature phases of K 3 H(SO 4 ) 2 , (NH 4 ) 3 H(SO 4 ) 2 and other superprotonic compounds M 3 H(AO 4 ) 2 . Impedance measurements performed on single crystals show high values of conductivity characteristic for superprotonic phases. Using the methods of impedance spectroscopy and atomic force microscopy, a significant anisotropy of the conductivity of crystals has been detected. It was also shown that there is a qualitative correlation of bulk and local conductivity measured for samples of the same composition and orientation at room temperature, which is due to the peculiarities of their crystal structure.