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Raman signatures of intermediate phase in quaternary Ge15Te80 (-) xIn5Agx glasses

Varma, Sreevidya G and Muthu, DVS and Sood, AK and Asokan, S (2014) Raman signatures of intermediate phase in quaternary Ge15Te80 (-) xIn5Agx glasses. In: JOURNAL OF NON-CRYSTALLINE SOLIDS, 387 . pp. 143-147.

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Official URL: http://dx.doi.org/10.1016/j.jnoncrysol.2014.01.006

Abstract

Micro-Raman studies are conducted on as-quenched and annealed Ge15Te80 -_xIn5Agx glasses to probe the structural network and its evolution with composition. These studies reveal the presence of tetrahedral GeTe4 structural units in as-quenched samples. Specific signatures of the intermediate phase (IP) are observed in the composition dependence of Raman frequencies and corresponding intensities of different modes in the composition range, 8 <= x <= 16. In addition, the Raman peak positions are found to shift with silver doping. Apart from the Raman results, the compositional dependence of density, molar volume and thermal diffusivity, observed in the present study, confirms the presence of the intermediate phase. In thermally annealed samples, a unique variation of Raman wave-numbers in the intermediate region is observed due to the retention of some of the local structure even after the sample is crystallized. The observed Raman peaks are attributed to crystalline tellurium and silver lattice vibrational modes. Based on our present and earlier studies, we propose the occurrence of three thresholds in Ge15Te80 - xIn5Agx glasses, namely percolation of rigidity, percolation of stress and the onset of chemical phase separation on a nanoscale at 8%, 16% and 20% of silver concentration respectively. (C) 2014 Elsevier B.V. All rights reserved.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to the ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
Keywords: Chalcogenide glasses; Intermediate phase; Reversibility window; Chemical threshold
Department/Centre: Division of Physical & Mathematical Sciences > Instrumentation Appiled Physics
Depositing User: Id for Latest eprints
Date Deposited: 12 Jun 2014 08:54
Last Modified: 12 Jun 2014 08:54
URI: http://eprints.iisc.ac.in/id/eprint/49049

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