Article abstract
Nature Materials 5, 977 - 981 (2006)
Published online: 5 November 2006 | doi:10.1038/nmat1760
Subject Categories: Geomaterials | Computation, modelling and theory
Transformation pathways of silica under high pressure
Liping Huang1,2, Murat Durandurdu1,3 & John Kieffer1
Abstract
Network-forming oxides with rigid polyhedral building blocks often possess significant capacity for densification under pressure owing to their open structures. The high-pressure behaviour of these oxides is key to the mechanical properties of engineering materials and geological processes in the Earth's interior. Concurrent molecular-dynamics simulations and first-principles calculations reveal that this densification follows a ubiquitous two-stage mechanism. First, a compact high-symmetry anion sublattice forms, as controlled by strong repulsion between the large oxygen anions, and second, cations redistribute onto the newly created interstices. The same mechanism is observed for two different polymorphs of silica, and in the particular case of cristobalite, is corroborated by the experimental finding of a previously unidentified metastable phase. Our simulations not only clarify the nature of this phase, but also identify its occurrence as key evidence in support of this densification mechanism.
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136, USA
- Present address: Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA
- Present address: Department of Physics, University of Texas at El Paso, El Paso, Texas 79968, USA
Correspondence to: John Kieffer1 e-mail: kieffer@umich.edu
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