Vibrational Analysis and Electrical Conduction Mechanism Investigations ofOrder Disorder Phase Transitions in [N(C3H7)4]2ZnBr4Compound

Abstract

Bis-Tetrapropylammoniumtetrabromozincate has been synthesized and characterized by X-ray, vibrational spectroscopy and impedance spectroscopy. The Rietveldrefinement of the XRD diffractogram confirms the crystallization of the compound through the monoclinic system (space group C 2/c ).A temperature study of the Raman scattering revealed two phase transitions at about T 1 =340 and T 2 =393K. The evolution of the wavenumber and the line width versus the temperature showed some singularities associated with the transitions, suggesting that they are governed by the re-orientation of the [N(C 3 H 7 ) 4 ]+organic part. The complex impedance plotted as semicircle arcs in the temperature range and the centers of the semicircles lie below the real axis, which indicates that the material is non-Debye type. Double semicircles were related to bulk and grain boundary effects. Furthermore, the alternating current conductivity of the [N(C 3 H 7 ) 4 ] 2 ZnBr 4 obeyed the Jonscher's law: σ AC (ω)=σ dc +Aω s and the conduction could be attributed to thecorrelated barrier hopping (CBH) model in region (I) and (II)and the Non-overlapping SmallPolaron Tunneling (NSPT) in region (III).