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Floppy modes and the Boson peak in crystalline and amorphous silicates: an inelastic neutron scattering study

Published online by Cambridge University Press:  05 July 2018

M. J. Harris ,
M. T. Dove  and
J. M. Parker
M. J. Harris
Affiliation:
ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, UK
M. T. Dove*
Affiliation:
Mineral Physics Group, Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK
J. M. Parker
Affiliation:
Department of Engineering Materials, Sheffield University, Mappin Street, Sheffield S1 3JD, UK
*
* E-mail: martin@esc.cam.ac.uk
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Abstract

We present the results of an inelastic neutron scattering study of a crystalline polymorph of SiO2 (α-quartz), and a number of silicate glasses (pure silica, SiO2, and three glasses in the alkali series (K,Li)2Si2O5). We demonstrate the presence of the Boson peak in the inelastic spectra of the crystalline and amorphous materials and argue that it arises simply from the dispersion characteristics of transverse acoustic modes. Furthermore, we investigate the role of the lower-energy floppy modes in the inelastic spectra, and show that they are controlled by chemical effects.

Keywords

floppy modesBoson peaksilicatesneutron scatteringinelastic spectra
Type
Research Article
Information
Mineralogical Magazine , Volume 64 , Issue 3 , June 2000 , pp. 435 - 440
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2000

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