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Article – Journal of Advanced Chemical Sciences

Journal of Advanced Chemical Sciences, Volume 2,Issue 2,2016 Pages 271-275

Solid Synthesis and Improved Structural Study of [0.7(Cu2HgI4):0.3(AgIx:CuI(1-x))] of Fast-Ion Conductor (x = 0.2, 0.4, 0.6 and 0.8 Mol. Wt. %)
Noorussaba, Afaq Ahmad*

An new series of fast ionic solids in the mixed system [0.7(Cu2HgI4):0.3(AgIx:CuI(1-x))] where x = 0.2, 0.4, 0.6 and 0.8 mol. wt. % respectively by solid state reaction of the appropriate solid mixtures and quenching them at particular temperature. Powdered samples of different compositions containing x mol. wt. % of (AgIx:CuI(1-x)) were synthesized by solid state reactions, using [Cu2HgI4] ternary halides as host. Powder specimens of these compositions were analysed using Differential Thermal Analysis (DTA), Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), Far-Infrared Transmission Spectra (FTIR) and x-ray Powder Diffraction (XRD) techniques. These studies have confirmed the formation of new products as revealed by the absence of diffraction peaks of parent materials in the XRD patterns. Among the various compositions, a significant number of peaks found to contain Ag+ and Cu+ in Cu2HgI4 respectively and DSC traces have indicated the characteristic β-α phase transition temperature of [0.7(Cu2HgI4):0.3(AgIx:CuI(1-x))] (where x = 0.2, 0.4, 0.6 and 0.8 mol. wt. %) at around 340-545 K. These changes due to crystalline defects or on increased Cu+-free volume in the tetragonal lattice. In addition, Ag and Cu substitution appears to stabilize the high-temperature, hexagonal structure to temperature well in excess of 340-545 K, associated correspondingly with the melting of the (Ag+:Cu+) sublattice and with the storage of iodide/or cadmium and iodide/or mercury sublattices. Fourier transmission infrared spectra of all the fast ionic conductors [0.7(Cu2HgI4):0.3(AgIx:CuI(1-x))] (where x = 0.2, 0.4, 0.6 and 0.8 mol. wt. % respectively) in the wavenumber range extending from 400 to 4000 cm-1 are also reported. From these studies the TO and LO models are assigned. FTIR measurements can provide information on the motion and environment of the ions.

Keywords: Ionic Solids; Fast-Ion Conductor; DTA; DSC; TGA;