Structural phase transition, optical and electrical properties of the hybrid material [(C2H5)4N]2ZnI4 - Le Mans Université Accéder directement au contenu
Article Dans Une Revue Journal of Solid State Chemistry Année : 2022

Structural phase transition, optical and electrical properties of the hybrid material [(C2H5)4N]2ZnI4

Résumé

The bis (tetra-ethylammonium) tetraiodo-zincate (II) was prepared by slow evaporation an aqueous stoichiometric mixture of tetra-ethylammonium iodide and zinc iodide at room temperature. This compound has been characterized by X-ray diffraction (XRD), thermal analysis, UV–vis spectroscopy and complex impedance spectroscopy. Single crystal X-ray diffraction analysis shows that the title compound crystallizes in the tetragonal system with space group P -4 21m.The differential thermal analysis (DTA) and temperature-controlled X-ray diffraction study reveal a reversible first order phase transition at about 444 K between low temperature-tetragonal and high temperature-orthorhombic forms of [(C2H5)4N]2ZnI4. Below 444 K, the low temperature form exhibits two linear regimes of thermal expansion with a change in the slope around 373 K which is ascribed to a second-order phase transition. The diffuse reflectance indicates the existence of an optical direct transition with the band gap energy is equal to 3.9 eV. The spectra of complex impedances obtained in the temperature range from 403 to 468 K were modelled by a combination of R//CPE elements. A change of conduction regime around 444 K is noted in the variation of the Ln (σDC.T) versus reciprocal temperature. In both regimes, the conductivity obeys the Arrhenius law with activation energies of 1.37 eV in regime I and 2.37 eV in regime II. Frequency dependence of the AC conductivity followed the universal Jonscher's power law.
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Dates et versions

hal-03767318 , version 1 (15-11-2022)

Identifiants

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H. Elgahami, J. Lhoste, S. Auguste, Gwenaël Corbel, A. Oueslati. Structural phase transition, optical and electrical properties of the hybrid material [(C2H5)4N]2ZnI4. Journal of Solid State Chemistry, 2022, 314, pp.123357. ⟨10.1016/j.jssc.2022.123357⟩. ⟨hal-03767318⟩
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