Nandini Garg and Surinder M Sharma 2007 J. Phys.: Condens. Matter 19 456201 doi:10.1088/0953-8984/19/45/456201
Nandini Garg1 and Surinder M Sharma
Show affiliationsStatic and dynamic high pressure experiments reveal that the behavior of α-cristobalite (SiO2) depends on the rate and the nature of stress loading. To understand this behavior we have carried out extensive molecular dynamics simulations. The response to rapid and simultaneous increase of the pressures and temperatures to the expected Hugoniot values was calculated. These simulations along the simulated Hugoniot path revealed that alpha cristobalite transforms to a new six coordinated phase beyond 16 GPa, 1410.3 K. We find that between 16 and 18 GPa, even after equilibrating for a very long time, the disorder in the stishovite-like phase persists. On release of pressure, this disordered state is retained, in agreement with the experimental observations. Simulations under slow pressure increase show that the observation of Cmcm is sensitive to pressure steps and that stishovite phase arises through the Cmcm phase.
62.50.-p High-pressure effects in solids and liquids
64.70.K- Solid–solid transitions
61.50.Ks Crystallographic aspects of phase transformations; pressure effects
Issue 45 (14 November 2007)
Received 1 June 2007, in final form 15 August 2007
Published 11 October 2007
Nandini Garg and Surinder M Sharma 2007 J. Phys.: Condens. Matter 19 456201
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