Dielectric Property Conduction Mechanism and Thermal Analysis of Cu1.09Ni0.91(HSeO3)2Cl2⋅4H2O Compound

The Cu1.09Ni0.91(HSeO3)2Cl2⋅4H2O (noted CuNiSe) compound was prepared from an aqueous solution reaction and crystallizes in the orthorhombic Pnma space group. It was analyzed by single-crystal X-ray diffraction and the X-ray powder diffraction to confirm the purity of the synthesized compound. The structure of this compound consists by a three-dimensional framework structure, constructed by layers parallel to the (010) plane formed by copper/nickel octahedral and (HSeO3−)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$_{3}^{\mathrm {-}})$\end{document} trigonal pyramids. The thermal analysis of the CuNiSe compound shows three endothermic peaks at 410, 433, and 473 K. The Raman spectra of CuNiSe have been recorded from 299 to 479 K. In addition, the dielectric evolution constant as a function of frequency and temperature revealed a ferroelectric–paraelectric phase transition about 433 K and superprotonic phase transition about 473 K. However, the conductivity evolution versus temperature confirmed the presence of these two types of phase transitions.