Impedance spectroscopic investigation on phase transition and electrical conduction mechanism of the new inorganic-organic complex: (C6H9N2)2HgCl4 (I), (C6H9N2)2(Hg0.75Cd0.25)Cl4 (II) and (C6H9N2)2(Hg0.12Zn0.88)Cl4 (III)

Abstract

The new organic-inorganic compounds, (C6H9N2)2HgCl4 (I), (C6H9N2)2(Hg0.75Cd0.25)Cl4 (II) and (C6H9N2)2(Hg0.12Zn0.88)Cl4 (III), was successful prepared using a hydrothermally synthesized and characterized by differential scanning calorimetry (DSC) and ac conductivity. The calorimetric study show that only the (I) compound has a phase transition at 349 K.Ac conductivity is been studied by means of impedance spectroscopy measurements, for the three compounds, in the 209 Hz–5 MHz frequency range from 298 to 398 K.Both Z′ and Z″ of complex impedance are well fitted to different equivalent circuit models. Besides, the alternating current (AC) conductivity of those investigated compounds obeys the Jonscher law: σ(ω) = σdc + Aωn. The temperature dependence of the Jonscher’s exponent shows that the conduction is analyzed by different processes, which can be attributed to several models. Thus, it’s is insured by the non-overlapping small Polaron tunneling (NSPT) and the correlated barrier hopping mode (CBH) in the first compound (I), whereas it was reasonably well interpreted by the overlapping-large polaron tunneling (OLPT) in the second and the third compounds.