MmHn(XO4)(m + n)/2 crystals: structure, phase transitions, hydrogen bonds, conductivity. II. Structure and properties of Cs3(HSO4)2(H2PO4) and Cs4(HSO4)3(H2PO4) single crystals.

Cs3(HSO4)2(H2PO4) and Cs4(HSO4)3(H2PO4) single crystals were obtained for the first time based on a systematic study of the phase diagram of the CsHSO4-CsH2PO4-H2O ternary system. To reveal the structural conditionality for anomalies in physical properties, including dielectric and optical properties, diffraction studies of the crystal structure of Cs3(HSO4)2(H2PO4) and Cs4(HSO4)3(H2PO4) were performed, and their common structural features and differences were analyzed.

M(m)H(n)(XO4)((m+n)/2) crystals: structure, phase transitions, hydrogen bonds, conductivity. I. K9H7(SO4)8·H2O crystals--a new representative of the family of solid acid conductors.

To reveal the structural conditionality for anomalies in physical properties, including dielectric and optical properties, diffraction studies of K9H7(SO4)8·H2O crystals were performed using synchrotron radiation in the temperature range 293-450 K and determined at 405 K, taking H atoms into account. The results indicate that the occurrence of high conductivity in K9H7(SO4)8·H2O crystals with a temperature increase is associated with the outward diffusion of water molecules, hydrogen-bond network rearrangement and the formation of channels for the possible motion of K(+) ions. A rearranged system of hydrogen bonds consists of permanent bonds and partly of dynamically disordered bonds.