Abstract

Bis-Tetrapropylammoniumtetrabromozincate has been synthesized and characterized by X-ray, vibrational spectroscopy and impedance spectroscopy. The Rietveld refinement 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 T₁=340 and T₂=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(C₃H₇)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(C₃H₇)₄]₂ZnBr₄obeyed the Jonscher’s law: σ_AC(ω)=σ_dc+Aω^s and the conduction could be attributed to the correlated barrier hopping (CBH) model in region (I) and (II)and the Non-overlapping Small Polaron Tunneling (NSPT) in region (III).