Low-temperature anomalies of the dielectric permeability of Sn2P2S6 crystals

What is it about?

Low-temperature anomalies of dielectric permittivity of Sn2P2S6 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.

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Photo by Fachrizal Maulana on Unsplash

Photo by Fachrizal Maulana on Unsplash

Why is it important?

In many crystals of the Me1Me2P2S(Se)6 family near temperatures 120-250 K, an anomaly on the temperature dependence of dielectric permittivity (a characteristic step on the temperature dependence of dielectric permittivity and a maximum on the dielectric loss curve) is observed, which shifts to higher temperatures with increasing frequency of the measuring field. This behavior indicates the presence of a relaxation process in the selected temperature range but does not answer the question about the mechanism of this relaxation. We observed a similar phenomenon in crystals CuInP2S6, CuGaP2S6, Cs2Ag2P2Se6, and in the mixed material Cu0.15Fe1.7PS3. Since this phenomenon is observed practically in all materials of the Me1Me2P2S(Se)6 family, most likely they have a common nature, the origin of which remains to be investigated.

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