Phase transitions in (C7H12N2)2[SnCl6]Cl2·1.5H2O crystal,studied by NMR and infrared spectroscopy |
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Authors: | Rachid Hajji Faouzi Hlel |
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Institution: | Laboratory of spectroscopic characterization and optics of materials, Faculty of Science of Sfax, University of Sfax, Sfax, Tunisia |
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Abstract: | The (C7H12N2)2SnCl6]Cl2·1.5H2O complex is a new member of the family of hybrid organic–inorganic perovskite compounds. It exhibits two order–disorder phase transitions with changes in the conformation of aromatic cations at the two transition temperatures 360 and 412 K. Differential scanning calorimetry, nuclear magnetic resonance (NMR), and Fourier-transform infrared (FT-IR) spectroscopy were used to investigate these phase transitions. These transition mechanisms were investigated in terms of the spin–lattice relaxation times T1 for 1H static NMR and the chemical shifts for 13C CP–MAS. The temperature dependence of T1(1H) and 13C chemical shifts are changed near TC1 and TC2. Furthermore, the splitting for 13C NMR signals in Phases (II) and (III) indicated a ferroelastic characteristic of the compound. In addition, FT-IR results indicate that the ordered conformational structure of aromatic cations undergoes a remarkable disorder with increasing temperature. The NMR and FT-IR studies suggest that the phase transition mechanisms are related to the reorientational motion of C7H12N2]2+ cations as a whole. Phase transition was examined in light of the interesting optical properties of this material. |
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Keywords: | chlorostannate (IV) crystal structure NMR spectroscopy phase transition relaxation time vibrational spectra |
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