Synthesis, crystal structure, thermal and physical properties of (C6H18N2)3[Sb4Cl18]
| Autor: | Slaheddine Kamoun, Houssem Eddine Ahmed |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Physics
Arrhenius equation Condensed matter physics Band gap Mechanical Engineering Relaxation (NMR) Metals and Alloys Analytical chemistry 02 engineering and technology Triclinic crystal system 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics Polaron 01 natural sciences 0104 chemical sciences Electronic Optical and Magnetic Materials Dielectric spectroscopy symbols.namesake Mechanics of Materials Phase (matter) Materials Chemistry symbols 0210 nano-technology Monoclinic crystal system |
| Zdroj: | Synthetic Metals. 221:299-308 |
| ISSN: | 0379-6779 |
| DOI: | 10.1016/j.synthmet.2016.09.019 |
| Popis: | The crystal structure of tris (N, N, N’, N’-tetramethylethylenediammonium) octadecachloridotetraantimonate (III) is built up of [(CH3)2NH(CH2)2NH(CH3)2]2+ cations connected to the one [Sb4Cl18]6n−n anionic chains by N—H⋯Cl hydrogen bonds. In this study, we found that this ionic compound exhibits a triclinic P 1 ¯ ↔ monoclinic P21/n structural phase transition at about (T1 = 356 ± 2 K) which has been characterized by X-rays powder analysis, DSC, AC conductivity and dielectric measurements. The optical band gap determined by diffuse reflection spectroscopy is 4.38 eV for a direct allowed transition. Impedance spectroscopy measurements of (C6H18N2)[Sb4Cl18] were conducted under various frequency settings (from 20 Hz to 2 MHz) and over the temperature range 309–398 K. The Cole-Cole (Z” versus Z’) plots are fitted to two equivalent circuits models. Combined impedance and modulus plots were used as tools to analyze the sample behaviour as a function of frequency at different temperatures. The frequency dependence of the AC conductivity is interpreted in terms of Jonscher’s law. The temperature dependence of the DC and the bulk σp conductivities are well explained by Arrhenius law. The conduction mechanisms are attributed to the quantum mechanical tunnelling (QMT) model in phase I and to the small polaron tunnelling (SPT) model in phase II. Our study has also revealed that the relaxation times are thermally activated and that the dipole process has a non-Debye behaviour. |
| Databáze: | OpenAIRE |
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