Proton conduction study of a new selenate-based hybrid compound

Ongoing studies aimed at developing a novel proton conducting solids, resulted in the new organic-inorganic compound [(C2H5)(4)N] HSeO4 (H2SeO4)(2). The crystals were prepared by slow evaporation technique at room temperature. Crystal structure, thermal and electrical measurements were provided to characterize this compound. Single-crystal X-ray study showed that the new phase crystallizes belongs to the Cc space group of the monoclinic system with lattice parameters: a = 19.705 (1) angstrom; b = 7.5420 (3) angstrom; c = 19.199 (1) angstrom, beta = 115 degrees. The structure consists of infinite two-dimensional inter-linkers via strong hydrogen bonds (O-H center dot center dot center dot O) giving birth to trimers. Two phase transition were disclosed by differential thermal analysis and confirmed by electrical measurements and dielectric measurements. The complex impedance of the compound was investigated in the temperature range 290-373 K and in the frequency range 1-13.10(3) KHz. Besides, an electrical equivalent circuit was proposed to explain the impedance results. Electric and dielectric analyses reveal the presence of a relaxation phenomenon and highlight the good protonic conduction of this material. Protons migration can be ascribed to the reorientation of protons carriers through hydrogen bonds, and then it occurs by the Grotthuss mechanism. (C) 2020 Elsevier B.V. All rights reserved.