Atomic structure of the two intermediate phase glasses SiSe4 and GeSe4

Carlo Massobrio, Massimo Celino, Philip S. Salmon, Richard A. Martin, Matthieu Micoulaut, Alfredo Pasquarello

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Abstract

The microscopic origin of the intermediate phase in two prototypical covalently bonded Ax B1-x network glass forming systems, where A=Ge or Si, B=Se, and 0≤x≤1, 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 A B4 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 Gex Se1-x and Six Se1-x glasses, a quantity that is linked to the finite width of the intermediate phase window. © 2009 The American Physical Society.
Original languageEnglish
Article number174201
Pages (from-to)-
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume79
Issue number17
DOIs
Publication statusPublished - 1 May 2009

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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