Joint diffraction and modeling approach to the structure of liquid alumina

Lawrie B. Skinner*, Adrian C. Barnes, Philip S. Salmon, Louis Hennet, Henry E. Fischer, Chris J. Benmore, Shinji Kohara, J. K. Richard Weber, Aleksei Bytchkov, Martin C. Wilding, John B. Parise, Thomas O. Farmer, Irina Pozdnyakova, Sonia K. Tumber, Koji Ohara

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

60 Citations (Scopus)

Abstract

The structure of liquid alumina at a temperature similar to 2400 K near its melting point was measured using neutron and high-energy x-ray diffraction by employing containerless aerodynamic-levitation and laser-heating techniques. The measured diffraction patterns were compared to those calculated from molecular dynamics simulations using a variety of pair potentials, and the model found to be in best agreement with experiments was refined using the reverse Monte Carlo method. The resultant model shows that the melt is composed predominantly of AlO4 and AlO5 units, in the approximate ratio of 2:1, with only minor fractions of AlO3 and AlO6 units. The majority of Al-O-Al connections involve corner-sharing polyhedra (83%), although a significant minority involve edge-sharing polyhedra (16%), predominantly between AlO5 and either AlO5 or AlO4 units. Most of the oxygen atoms (81%) are shared among three or more polyhedra, and the majority of these oxygen atoms are triply shared among one or two AlO4 units and two or one AlO5 units, consistent with the abundance of these polyhedra in the melt and their fairly uniform spatial distribution.

Original languageEnglish
Article number024201
Number of pages16
JournalPhysical Review B: Condensed Matter and Materials Physics
Volume87
Issue number2
DOIs
Publication statusPublished - 3 Jan 2013

Keywords

  • MOLECULAR-DYNAMICS SIMULATION
  • X-RAY-DIFFRACTION
  • CONTROLLED PROFILE CRYSTALS
  • MONTE-CARLO-SIMULATION
  • HIGH-PRESSURE
  • COMPUTER-SIMULATION
  • NEUTRON-DIFFRACTION
  • SURFACE-TENSION
  • COORDINATION CHANGES
  • UNDERCOOLED ALUMINA

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