Electrical conductivity and vibrational studies induced phase transition in [N(C<sub>3</sub>H7)4]<sub>2</sub>ZnBr<sub>4</sub> compound
Souad Chkoundali, Abdelhedi Aydi
Abstract
Bis-Tetrapropylammonium tetrabromozincate was synthesized and characterized by X-ray powder diffraction, as well as vibrational and impedance spectroscopy. Rietveld’s refinement of X-ray diffractogram confirmed the crystallization of the compound through the monoclinic system (space group [Formula: see text]. A temperature study of Raman scattering revealed two phase transitions at approximately [Formula: see text] = 340 K and [Formula: see text] = 393 K. The wavenumber and the line width’s evolution as a function of temperature showed some peculiarities associated with these transitions, which suggests that they are governed by the reorientation of the organic part [N(C 3 [Formula: see text]][Formula: see text]. The complex impedance plotted as a double semicircular arc in the studied temperature range and the centers of these semicircles lie below the real axis, which indicates that the material is an on-Debye type. These semicircular arcs are related to the bulk and the grain boundary effects. Furthermore, the alternating current conductivity of [N(C 3 [Formula: see text]] 2 ZnBr 4 obeyed Jonscher’s law: [Formula: see text] = [Formula: see text] and the conduction could be attributed to the correlated barrier hopping (CBH) model in both region(I) and (II) and the Non-overlapping Small Polaron Tunneling (NSPT) in region (III).