Structure–property relationships in critically connected (GeTe4)100−x(As2Se3)x glasses. Issue 32 (29th July 2022)

• Record Type: Journal Article
• Authors: Chahal, Shweta; Prabhudessai, Akila G.; Shekhawat, Roopali; Vinoth, S.; Ramesh, K.
• Is Part Of: Dalton transactions. Volume 51:Issue 32(2022)
• Page Start: 12100
• Page End: 12113
• Publication Date: 2022-07-29
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d2dt01969h
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : (GeTe4 )100− x (As2 Se3 ) x glasses having an average coordination number ( Z av ) = 2.4 show minimum fragility, indicating strong nature of the melts. This study also brings out the dominance of chemical composition effects over the network connectivity. Abstract : Thermal, optical, mechanical and structural studies were carried out on glasses in the pseudo-binary joint GeTe4 –As2 Se3 prepared by a melt quenching method. (GeTe4 )100− x (As2 Se3 ) x glasses in the entire composition range of 0 ≤ x ≤ 100 have an average coordination number ( Z av ) = 2.4, where the glass forming ability is found to be maximum. In general, for Z av ≤ 2.4, the glass transition is found to be dominated by the network connectivity and the chemical composition effects are minimal. Although Z av of Ge20 Te80 (GeTe4 ) and As2 Se3 (As40 Se60 ) is 2.4, GeTe4 is a poor glass former and As2 Se3 is an excellent glass former. The glass-forming ability is expected to increase with the addition of As2 Se3 . Surprisingly, the glass forming ability is found to decrease with the initial addition of As2 Se3 and then shows an increasing trend. Glass transition ( T g ) 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 T g shows a decreasing trend, region II (25 ≤ x ≤ 55) where T g remains almost constant and region III (60 ≤ x ≤ 100) where T g 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 As2 Se3 . 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 As2 Se3 . 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.