Structural model of homogeneous As-S glasses derived from Raman spectroscopy and high-resolution XPS

R. Golovchak, O. Shpotyuk, J. Mccloy, B. Riley, C. Windisch, S. Sundaram, A. Kovalskiy, H. Jain.

Philosophical Magazine, vol. 90, No. 34, 2010, p. 4489–4501.

Abstract

The structure of homogeneous bulk AsxS100-x (25 ≤ x ≤ 42) glasses, prepared by the conventional rocking–melting–quenching method, was investigated using high-resolution X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. It is shown that the main building blocks of their glass networks are regular AsS3/2 pyramids and sulfur chains. In the S-rich domain, the existence of quasi-tetrahedral (QT) S=As(S1/2)3 units is deduced from XPS data, but with a concentration not exceeding 3–5% of total atomic sites. Therefore, QT units do not appear as primary building blocks of the glass backbone in these materials, and an optimally-constrained network may not be an appropriate description for glasses when x < 40. It is shown that, in contrast to Se-based glasses, the ‘chaincrossing’ model is only partially applicable to sulfide glasses.

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