Atomic structure of the two intermediate phase glasses SiSe4 and GeSe4

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

Research output: Contribution to journalArticlepeer-review


The microscopic origin of the intermediate phase in two prototypical covalently bonded AxB1-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 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 GexSe1-x and SixSe1-x glasses, a quantity that is linked to the finite width of the intermediate phase window.
Original languageEnglish
Article number174201
JournalPhysical Review B
Issue number17
Publication statusPublished - 4 May 2009


  • intermediate phase
  • prototypical covalently bonded AxB1−x network glass forming systems
  • A=Ge
  • Si
  • B=Se
  • 0≤x≤1
  • neutron diffraction
  • molecular-dynamics methods
  • glassy
  • GeSe4
  • SiSe4
  • structure factor
  • pair-correlation function


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