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The [(C 2 H 5 )NH 3 ] 2 ZnCl 4 hybrid material was prepared and their calorimetric study and electric properties were investigated at low temperature. Indeed, the X-ray powder diffraction confirms the purity of the synthesized compound and the differential scanning calorimetric show several phase transitions at 231 K, 234 K, 237 K, 247 K and 312 K, which are proven by the variation of σ p and σ dc as a function of temperature. The equivalent circuit based on the Z-View-software was proposed and the conduction mechanisms were determined. The alternative current (ac) electrical conduction in [(C 2 H 5 )NH 3 ] 2 ZnCl 4 is studied by two processes that can be attributed to a hopping transport mechanism. These processes are the correlated barrier hopping (CBH) model in regions I and IV and the overlapping large-polaron tunneling (OLPT) model in region III. The optical study was also investigated by UV–vis absorption. In fact, the insulating behaviour of the material is established by Tauc plot obtaining a large value of indirect optical band gap energy.

The present paper accounted for the synthesis, electric properties and vibrational spectroscopy of [N(CH 3)4]2CoCl2Br2 . The dielectric spectra were measured in the frequency range 10 −1-105 Hz and temperature interval from 223 to 393 K. The dielectical properties confirm the ferroelectric–paraelectric phase transition at 290 K, which is reported by Abdallah Ben Rhaiem et al. (2013). The equivalent circuit based on the Z-View-software was proposed and the conduction mechanisms were determined. The obtained results have been discussed in terms of the correlated barrier hopping model (CBH) in phase I and non-overlapping small polaron tunneling model (NSPT) in phases II and III. Raman spectra as function temperature have been used to characterize the phase transitions and their nature, which indicates a change of the some peak near the transitions phase.

The [(C2H5)NH3]2CuCl4 compound was prepared and characterized by several technique: the X-ray powder diffraction confirms the purity of the synthetized compound, the differential scanning calorimetric show several phase transitions at 236 K, 330 K, 357 K and 371 K, the dialectical properties confirms the ferroelectric–paraelectric phase transition at 238 K, which is reported by V. Kapustianyk et al. (2007) [1]. The two semi-circles observed in the complex impedance identify the presence of the grain interior and grain boundary contributions to the electrical response in this material. The equivalent circuit is modeled by a combination series of two parallel RP–CPE circuits. The temperature dependence of the alternative current conductivity (σg) and direct current conductivity (σdc) confirm the observed transitions in the calorimetric study. The (AC) electrical conduction in [(C2H5)NH3]2CuCl4 was studied by two processes that can be attributed to a hopping transport mechanism: the non-overlapping small polaron tunneling (NSPT) model in phase III and the correlated barrier hopping (CBH) model in phases I, II, IV, V and VI.

The present paper accounted for the synthesis, differential scanning calorimetric and vibrational spectroscopy of [C2H5NH3]2ZnCl4grown at room temperature. Differential scanning calorimetric (DSC) disclosed five phase transitions at T1=231 K, T2=234 K, T3=237 K, T4=247 K and T5=312 K. The temperature dependence of the dielectric constant at different temperatures proved that this compound is ferroelectric below 238 K. Raman spectra as function temperature have been used to characterize these transitions and their nature, which indicates a change of the some peak near the transitions phase. The analysis of the wavenumber and the line width based on the order–disorder model allowed to obtain information relative to the thermal coefficient and the activation energy near the transitions phase.

The [(C 2 H 5 )NH 3 ] 2 CdCl 4 hybrid material was prepared and its calorimetric study and electric properties were investigated at low temperature. The X-ray powder diffractogram has shown that the compound is crystallized in the orthorhombic system with Abma space group, and the refined unit cell parameters are a =7.546 A, b =7.443 A, and c =21.831 A. The calorimetric study has revealed two endothermic peaks at 216 K and 357 K, which are confirmed by the variation of f p and σ dc as a function of temperature. The equivalent circuit based on the Z-View-software was proposed and the conduction mechanisms were determined. The obtained results have been discussed in terms of the correlated barrier hopping model (CBH) in phase I (low temperature (OLT)), non-overlapping small polaron tunneling model (NSPT) in phase II (room temperature (ORT)) and the overlapping large polaron tunneling model in phase III (high temperature (OHT)). The density of localized states N F ( E ) at the Fermi level and the binding energy W m were calculated. The variation of the dielectric loss log( e ʺ) with log( ω ) was found to follow the empirical law, e ″= B ω m ( T ) .