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Comparison of Neutron Elastic and Inelastic Scattering from Fused Quartz, Cab-O-Sil and Aerogel

Published online by Cambridge University Press:  21 February 2011

John H. Root ,
William J. L. Buyers ,
John H. Page ,
Dale W. Schaefer  and
C. J. Brinker
John H. Root
Affiliation:
Atomic Energy of Canada Ltd., Chalk River, Ontario, Canada, KOJ 1JO
William J. L. Buyers
Affiliation:
Atomic Energy of Canada Ltd., Chalk River, Ontario, Canada, KOJ 1JO
John H. Page
Affiliation:
University of Manitoba, Winnipeg, Manitoba, Canada, R3T 2N2
Dale W. Schaefer
Affiliation:
University of Manitoba, Winnipeg, Manitoba, Canada, R3T 2N2
C. J. Brinker
Affiliation:
Sandia National Laboratories, Albuquerque, NM 87185
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Abstract

Neutron scattering experiments have been performed to study the structure and dynamics of three preparations of silica: a dense glass (fused quartz), a flame-hydrolyzed aggregate (Cab-O-Sil, grade M5) and a polymeric aerogel. The experiments were performed on the three materials at temperatures selected from 300, 77 and 4.2 K. Neutron inelastic scattering was measured at Q = 2.5, 2.9 and 4.0 Å−1.

The elastic scattering indicates a systematic decrease in positional correlations on progressing from fused quartz through Cab-O-Sil to aerogel. The inelastic scattering was analyzed with the Buchenau model [1] to obtain the sample, Q and temperature dependences of the density of states, g(v). In the aerogel g(v) increases with temperature at frequencies greater than 1.5 THz and is enhanced at Q = 2.5 Å−1. Thus a complete explanation of the inelastic scattering from aerogels must account for multiphonon processes, local antiphase motions and anharmonic effects.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 166: Symposium J – Neutron Scattering for Materials Science , 1989 , 379
Copyright
Copyright © Materials Research Society 1990

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References

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