Structure and topology of silica aerogels

Schaefer, D. W.; Olivier, B. J.; Ashley, C. S.; Richter, D.; Farago, B.; Frick, B.; Hrubesh, L.; van Bommel, M. J.; Long, G.; Krueger, S.

doi:10.1016/s0022-3093(05)80438-7

Structure and topology of silica aerogels

Conference · Mon Sep 30 04:00:00 EDT 1991 · Journal of Non-Crystalline Solids

DOI:https://doi.org/10.1016/s0022-3093(05)80438-7· OSTI ID:10105735

Schaefer, D. W. ^[1]; Olivier, B. J. ^[1]; Ashley, C. S. ^[1]; Richter, D. ^[2]; Farago, B. ^[3]; Frick, B. ^[3]; Hrubesh, L. ^[4]; van Bommel, M. J. ^[5]; Long, G. ^[6]; Krueger, S. ^[6]

Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Institut für Festkörperforschung KFA Jülich GmbH (Germany)
Inst. Laue-Langevin (ILL), Grenoble (France)
Lawrence Livermore Laboratory (LLL), Livermore, CA (United States)
Philips Research Laboratories, Eindhoven, (NL)
National Institute of Standards and Technology (NIST), Gaithersburg, MD (United States)

Neutron spin-echo spectroscopy is used to study the topology of aerogels. Topology or connectivity is varied through precursor chemistry and thermal annealing. Topology is characterized using the concept of fractons (the vibrational excitations of a fractal network). A qualitative difference is observed in the spectrum of polymeric vs colloidal aerogels, the latter showing a peak in the density of vibrational states. For colloidal aerogels whose structure appears to arise from phase separation in the solution precursor, low-energy excitations were only observed in the lowest density material studied. Finally, a transition from fractal to colloidal microstructure was observed during the sintering of polymeric aerogels. This transformation revealed itself as a transition from a fracton-like to a peaked density of states function.

Research Organization:: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

Sponsoring Organization:: USDOE

DOE Contract Number:: AC04-76DP00789; W-7405-ENG-48

OSTI ID:: 10105735

Report Number(s):: SAND--91-2509C; CONF-910960--3; ON: DE92004728

Conference Information:: Journal Name: Journal of Non-Crystalline Solids Journal Volume: 145

Country of Publication:: United States

Language:: English

References (13)

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Related Subjects

36 MATERIALS SCIENCE
360602
663610
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANNEALING
COLLOIDS
MORPHOLOGY
NEUTRON PHYSICS
NEUTRON SPECTROSCOPY
POLYMERS
SILICA
SINTERING
SPIN ECHO
STRUCTURE AND PHASE STUDIES
TOPOLOGY
VIBRATIONAL STATES

Structure and topology of silica aerogels

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References (13)

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