Thermal diffusivity measurements on As-Te-Ga glasses by photo-thermal deflection technique: Composition dependence and topological thresholds

Manikandan, N and Paulraj, M and Asokan, S (2009) Thermal diffusivity measurements on As-Te-Ga glasses by photo-thermal deflection technique: Composition dependence and topological thresholds. In: Journal of Non-Crystalline Solids, 355 (1). pp. 58-60.

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Abstract

The thermal diffusivity (alpha) of As20Te80-xGax glasses (7.5 <= x <=18.5) has been measured using photo-thermal deflection (PTD) technique. It is found that the thermal diffusivity is comparatively lower for As-20 Te80-xGax glasses, which is consistent with the memory type of electrical switching exhibited by these samples. Further, the thermal diffusivity of As20Te80-xGax, glasses is found to increase with the incorporation of gallium initially (for x <= 9), which is consistent with the metallicity of the additive, This increase in alpha results in a maximum at the composition x = 9; beyond x = 9, a decrease is seen in alpha leading to a minimum at the composition x = 15. The observed composition dependence of thermal diffusivity Of As-20 Te80-xGax glasses has been found to be similar to that of As20AsxTe100-x glasses, based on which it is proposed that As20Te80-xGax, glasses exhibit an extended stiffness transition with compositions x = 9 and x = 15 being its onset and completion, respectively. Also, the composition x = 17.5 at which a second maximum is seen in the thermal diffusivity has been identified to be the chemical threshold (CT) of the As-20 Te80-xGax glassy system, as at CT, the glass is configurationally closest to the crystalline state and the scattering of the diffusing thermal waves is minimal for the chemically ordered phase.

Item Type:	Journal Article
Publication:	Journal of Non-Crystalline Solids
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Chalcogenides;Calorimetry.
Department/Centre:	Division of Physical & Mathematical Sciences > Instrumentation Appiled Physics
Date Deposited:	30 Oct 2009 10:45
Last Modified:	19 Sep 2010 05:27
URI:	http://eprints.iisc.ac.in/id/eprint/19181

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