Atomic structure of the two intermediate phase glasses SiSe4 and GeSe4

Carlo Massobrio, Massimo Celino, Philip S. Salmon, Richard A. Martin, Matthieu Micoulaut, and Alfredo Pasquarello
Phys. Rev. B 79, 174201 – Published 4 May 2009

Abstract

The microscopic origin of the intermediate phase in two prototypical covalently bonded AxB1x network glass forming systems, where A=Ge or Si, B=Se, and 0x1, was investigated by combining neutron diffraction with first-principles molecular-dynamics methods. Specifically, the structure of glassy GeSe4 and SiSe4 was examined, and the calculated total structure factor and total pair-correlation function for both materials are in good agreement with experiment. The structure of both glasses differs markedly from a simple model comprising undefective AB4 corner-sharing tetrahedra in which all A atoms are linked by B2 dimers. Instead, edge-sharing tetrahedra occur and the twofold coordinated Se atoms form three distinct structural motifs, namely, Se-Se2, Se-SeGe (or Se-SeSi), and Se-Ge2 (or Se-Si2). This identifies several of the conformations that are responsible for the structural variability in GexSe1x and SixSe1x glasses, a quantity that is linked to the finite width of the intermediate phase window.

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  • Received 8 September 2008

DOI:https://doi.org/10.1103/PhysRevB.79.174201

©2009 American Physical Society

Authors & Affiliations

Carlo Massobrio1, Massimo Celino2, Philip S. Salmon3, Richard A. Martin3, Matthieu Micoulaut4, and Alfredo Pasquarello5,6

  • 1Institut de Physique et de Chimie des Matériaux de Strasbourg, 23 rue du Loess, BP43, F-67034 Strasbourg Cedex 2, France
  • 2ENEA, Ente per le Nuove Tecnologie, l’Energia e l’Ambiente, Unità Materiali e Nuove Tecnologie, C.R. Casaccia, CP 2400, 00100 Roma, Italy
  • 3Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
  • 4Laboratoire de Physique Théorique des Liquids, Université Pierre et Marie Curie, 4 Place Jussieu, F-75252 Paris Cedex 05, France
  • 5Institute of Theoretical Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
  • 6Institut Romand de Recherche Numérique en Physique des Matériaux (IRRMA), CH-1015 Lausanne, Switzerland

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Issue

Vol. 79, Iss. 17 — 1 May 2009

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