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Article – Journal of Nanoscience and Technology

Journal of Nanoscience and Technology, Volume 2,Issue 3,2016 Pages 140-143

Preparation, Crystal Structure, Thermal Properties and Vibrational Modes of Tl2CdI4 Nanocomposite Material
Noorus Saba*, Afaq Ahmad

The new compound Tl2CdI4 has been prepared and characterized by IR spectroscopy, powder X-ray diffraction, thermal analysis, far IR spectroscopy. The compounds Tl2CdI4 for which phase diagrams are available in the literature were characterized by IR spectroscopy and their identities were confirmed by far-IR spectroscopy, X-ray powder diffraction and thermal analysis. Tl2CdI4, undergoes a sharp order-disorder phase transition at elevated temperatures that can be detected by the measurement of IR spectra as a function of temperature. This work suggests that thallium (I) ionic conductors may exist, analogous to some well-known double salt conductors based on simple silver (I) and copper (I) halides. In addition, the present study demonstrates the usefulness of IR spectroscopy in the characterization of heavy metal ionic conductors. The mobility of Tl+ in halide compounds has been investigated to develop an understanding of the factors which are important in fast ion conduction. These compounds are characterized by transitions at elevated temperatures to disordered phases in which the M ion is highly mobile. Trends in the transition temperatures, conductivities, and activation energies for ion transport demonstrate that Tl+ are less mobile than Cu+ and Ag+. The crystal structure of the low-temperature phase of Tl2CdI4 has been determined at 160 °C. The material crystallizes with two formula units in space group C22-P21 of the monoclinic system in a cell of dimensions a = 7.661 Å, b = 7.971 Å, c = 10.074 Å, β = 118.39°. The Cd+ ions are tetrahedrally coordinated by I- ions. The TI+ ions are found to reside in seven-coordinate sites approximating C2v, capped trigonal prisms. There is no clear-cut migration path for the Tl+ ions, but some plausible conduction mechanisms are discussed.

Keywords: Fast Ion Conductor; X-Ray Powder Diffraction; Thermal Analysis;