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Length scale dependence of high-pressure amorphization: the static amorphization of anorthite

Published online by Cambridge University Press:  05 July 2018

Simon A. T. Redfern
Simon A. T. Redfern*
Affiliation:
Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, UK
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Abstract

High-pressure amorphization of anorthite has been observed by energy-dispersive X-ray diffraction of powdered samples held under static pressure in a diamond anvil cell. The onset of amorphization is accompanied by a significant reduction in the intensity of Bragg reflections at pressures between 10 and 14 GPa, and anorthite becomes completely X-ray amorphous between 14 and 20 GPa. These pressures are significantly lower than those suggested by earlier birefringence studies. The discrepancy can be reconciled in terms of a model of high-pressure amorphization in which partially amorphized anorthite can be regarded as a spatially heterogeneous anti-glass, with long-range order maintained but translational disorder dominating at shorter correlation lengths.

Keywords

high-pressure amorphizationanorthiteanti-glassmetamictisation
Type
Mineralogy
Information
Mineralogical Magazine , Volume 60 , Issue 400 , June 1996 , pp. 493 - 498
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1996

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