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Science 27 May 2005:
Vol. 308. no. 5726, pp. 1299 - 1302
DOI: 10.1126/science.1109411
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Reports

Identifying Vibrations That Destabilize Crystals and Characterize the Glassy State

G. N. Greaves,1 F. Meneau,1,2 O. Majérus,1,3 D. G. Jones,1 J. Taylor4

High-resolution inelastic neutron scattering was used to identify major sources of low-frequency vibrations in zeolite crystals. Dispersed and nondispersed modes were found, both of which are prominent in the early stages of compressive amorphization but decline dramatically in strength once a glass of conventional density is created. By identifying the dispersed modes with the characteristic vibrations of the various secondary building units of zeolitic structures, the Boson peak, a characteristic of the glassy state, can be attributed to vibrations within connected rings of many different sizes. The nondispersed phonon features in zeolites, retained in the amorphized glass, were also replicated in silica. These modes are librational in origin and are responsible for destabilizing the microporous crystalline structure, for converting the resulting glass from a low- to a high-density phase, and for the associated changes in network topology that affect the Boson peak.

1 Institute of Mathematical and Physical Sciences, University of Wales, Aberystwyth, SY23 3BZ, UK.
2 Netherlands Organisation for Scientific Research (NWO), DUBBLE CRG/ESRF, Post Office Box 220, F38043 Grenoble Cedex, France.
3 Ecole Nationale Supérieure de Chimie de Paris, 11 rue Pierre et Marie Curie, 75231, Paris, France.
4 ISIS Facility, Rutherford Appleton Laboratory, Chilton, OX11 0QX, UK.

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Detection of First-Order Liquid/Liquid Phase Transitions in Yttrium Oxide-Aluminum Oxide Melts.
G. N. Greaves, M. C. Wilding, S. Fearn, D. Langstaff, F. Kargl, S. Cox, Q. V. Van, O. Majerus, C. J. Benmore, R. Weber, et al. (2008)
Science 322, 566-570
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