Structural and vibrational study of the negative thermal expansion in liquid As2Te3

Céline Otjacques, Jean-Yves Raty, Françoise Hippert, Helmut Schober, Mark Johnson, René Céolin, and Jean-Pierre Gaspard
Phys. Rev. B 82, 054202 – Published 10 August 2010

Abstract

We present an experimental and theoretical study of liquid As2Te3. This alloy exhibits a negative thermal expansion (NTE) in a 250 K range above the melting temperature Tm=654K. We evidence the changes in As2Te3 structure by measuring neutron-diffraction spectra at five temperatures in the NTE range and perform first principles molecular dynamics simulations at the same temperatures and densities to study the local order evolution in the liquid. Our calculated structures show an increase in the coordination numbers and a symmetrization of the first neighbors shell around atoms when the temperature rises. To confirm these results, we performed inelastic neutron scattering to obtain the vibrational density of state (VDOS) along the NTE. We see a clear change in the VDOS, consisting in a redshift of the highest frequencies with temperature. Finally, electrical conductivity evolution was obtained from the simulated structures, to compare with the semiconductor to metal transition measured experimentally.

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  • Received 3 March 2010

DOI:https://doi.org/10.1103/PhysRevB.82.054202

©2010 American Physical Society

Authors & Affiliations

Céline Otjacques1,*, Jean-Yves Raty1, Françoise Hippert2, Helmut Schober3, Mark Johnson3, René Céolin4, and Jean-Pierre Gaspard1

  • 1Condensed Matter Physics Laboratory, University of Liège, B5, B-4000 Sart-Tilman, Belgium
  • 2LMGP-CNRS-Grenoble INP, 3 Parvis L. Néel, 38016 Grenoble-Cedex 1, France
  • 3Institut Laue Langevin, BP 38042, BP 220, Grenoble Cedex, France
  • 4Faculté des Sciences Pharmaceutiques et Biologiques, Université Paris Descartes, 4 av. de l’Observatoire EA4066, 75006 Paris, France

  • *celine.otjacques@ulg.ac.be

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Vol. 82, Iss. 5 — 1 August 2010

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