Article abstract
Nature Materials 2, 622 - 629 (2003)
Published online: 24 August 2003 | doi:10.1038/nmat963
Subject Categories: Glasses | Porous materials
The rheology of collapsing zeolites amorphized by temperature and pressure
G. N. Greaves1, F. Meneau1,2, A. Sapelkin3, L. M. Colyer4, I. ap Gwynn5, S. Wade5 & G. Sankar2
Abstract
Low-density zeolites collapse to the rigid amorphous state at temperatures that are well below the melting points of crystals of the same composition but of conventional density. Here we show, by using a range of experimental techniques, how the phenomenon of amorphization is time dependent, and how the dynamics of order–disorder transitions in zeolites under temperature and pressure are equivalent. As a result, thermobaric regions of instability can be charted, which are indicative of polyamorphism. Moreover, the boundaries of these zones depend on the rate at which temperature or pressure is ramped. By directly comparing the rheology of collapse with structural relaxation in equivalent melts, we conclude that zeolites amorphize like very strong liquids and, if compression occurs slowly, this is likely to lead to the synthesis of perfect glasses.
- Institute of Mathematical and Physical Sciences, University of Wales, Aberystwyth SY23 3BZ, UK
- Royal Institution of Great Britain, 21 Albemarle Street, London W1X 4BS, UK
- Department of Chemistry, De Montfort University, Leicester LE1 9BH, UK
- Department of Chemistry, University of Keele, Staffordshire ST5 5BG, UK
- Institute of Biological Studies, University of Wales, Aberystwyth SY23 3DA, UK
Correspondence to: G. N. Greaves1 e-mail: gng@aber.ac.uk
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