Structure-property relationships in critically connected (GeTe4)100−x(As2Se3)x glasses

Chahal, S and Prabhudessai, AG and Shekhawat, R and Vinoth, S and Ramesh, K (2022) Structure-property relationships in critically connected (GeTe4)100−x(As2Se3)x glasses. In: Dalton Transactions, 51 . pp. 12100-12113.

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Abstract

Thermal, optical, mechanical and structural studies were carried out on glasses in the pseudo-binary joint GeTe4-As2Se3 prepared by a melt quenching method. (GeTe4)100−x(As2Se3)x glasses in the entire composition range of 0 ≤ x ≤ 100 have an average coordination number (Zav) = 2.4, where the glass forming ability is found to be maximum. In general, for Zav ≤ 2.4, the glass transition is found to be dominated by the network connectivity and the chemical composition effects are minimal. Although Zav of Ge20Te80 (GeTe4) and As2Se3 (As40Se60) is 2.4, GeTe4 is a poor glass former and As2Se3 is an excellent glass former. The glass-forming ability is expected to increase with the addition of As2Se3. Surprisingly, the glass forming ability is found to decrease with the initial addition of As2Se3 and then shows an increasing trend. Glass transition (Tg) shows a large variation from 175 °C for x = 0 to 108 °C for x = 30. Based on the variation in the properties, the tie-line can be divided into three regions: region I (0 ≤ x ≤ 20) where Tg shows a decreasing trend, region II (25 ≤ x ≤ 55) where Tg remains almost constant and region III (60 ≤ x ≤ 100) where Tg shows an increasing trend. Hardness measurement also shows a similar trend in the three regions. Thermal stability shows a continuous increase with the increase of As2Se3. The fragility index varies between 15 and 30 for all these glasses except for x = 0 (GeTe4) indicating the strong nature of the melts containing As2Se3. Raman studies indicate that the glassy network is dominated mainly by GeTe(4/2) in region I and in region III the network is dominated by AsSe(3/2) based structures. Glasses in region II are found to be dominated by AsTe3/2 based structures. This study brings out the dominance of chemical composition effects over the network connectivity in a critically coordinated network. These glasses are also found to transmit IR light up to 18 μm and offer a wide composition range to prepare bulk glasses to be useful for infrared applications.

Item Type:	Journal Article
Publication:	Dalton Transactions
Publisher:	Royal Society of Chemistry
Additional Information:	The copyright for this article belongs to the Royal Society of Chemistry.
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	23 Aug 2022 05:24
Last Modified:	23 Aug 2022 05:24
URI:	https://eprints.iisc.ac.in/id/eprint/76162

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