Temperature-Induced Density Anomaly in Te-Rich Liquid Germanium Tellurides: p versus sp3 Bonding?

Christophe Bichara, Mark Johnson, and Jean Yves Raty
Phys. Rev. Lett. 95, 267801 – Published 23 December 2005

Abstract

The density anomaly of liquid Ge0.15Te0.85 measured between 633 and 733 K is investigated with ab initio molecular dynamics calculations at four temperatures and at the corresponding experimental densities. For box sizes ranging from 56 to 112 atoms, an 8 k-points sampling of the Brillouin zone is necessary to obtain reliable results. Contrary to other Ge chalcogenides, no sp3 hybridization of the Ge bonding is observed. As a consequence, the negative thermal expansion of the liquid is not related to a tetrahedral bonding as in the case of water or silica. We show that it results from the symmetry recovery of the local environment of Ge atoms that is distorted at low temperature by a Peierls-like mechanism acting in the liquid state in the same way as in the parent solid phases.

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  • Received 17 May 2005

DOI:https://doi.org/10.1103/PhysRevLett.95.267801

©2005 American Physical Society

Authors & Affiliations

Christophe Bichara

  • CRMCN–CNRS and Aix-Marseille Universities, Campus de Luminy, Case 913, F13288 Marseille, France

Mark Johnson

  • Institut Laue Langevin, 6 rue Jules Horowitz, BP 156, Grenoble, France

Jean Yves Raty

  • Physique de la Matière Condensée, B5, Université de Liège, B4000 Sart-Tilman, Belgium

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Vol. 95, Iss. 26 — 31 December 2005

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