Low-temperature anomalies of the dielectric permeability of Sn₂P₂S₆ crystals

Low-temperature anomalies of dielectric permittivity of $S n 2 P 2 S 6$ crystals were investigated. It is shown that these phenomena have a relaxation character and the observed anomalies could be related to the small hole polarons dynamics with donor-acceptor compensation processes in lattice with tin and sulfur vacancies. To confirm it, we measured the dielectric properties of tin-enriched and sulfur-enriched crystals. It is shown that deviation from stoichiometry leads to a significant change in the low-temperature anomalies of dielectric losses.