Regensburg 2004 – wissenschaftliches Programm
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DF: Dielektrische Festkörper
DF 2: Elektrische und optische Eigenschaften II
DF 2.3: Vortrag
Montag, 8. März 2004, 15:30–15:50, H11
Dynamic simulation of the pressure transformations in crystalline Al2O3 — •Sandro Jahn1, Mark Wilson2, and Paul A. Madden1 — 1PTCL, Oxford University, South Parks Road, Oxford OX1 3QZ, UK — 2Department of Chemistry, UCL, 20 Gordon Street, London WC1H 0AJ, UK
The high pressure phase behavior of crystalline Al2O3 is studied using molecular dynamics. For the atomic interactions we use an ashperical ion model (AIM), which incorporates both many-body polarization and short-range ion distortion. The model parameters are obtained by fitting to system properties extracted from well directed electronic structure calculations. The application and removal of pressure results in two phase transformations to and from the Rh2O3-II and an orthorhombic perovskite structure, respectively. The high pressure phases are understood in terms of changes in the ion coordination environments and corundum grain boundaries. The observed structures may have significant implications for the frequencies of the fluorescence lines of Cr+-doped Ruby pressure markers at extreme pressures.