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Diffusion processes in confined materials.

Authors
  • Aksnes, D W
  • Gjerdåker, L
  • Allen, S G
  • Booth, H F
  • Strange, J H
Type
Published Article
Journal
Magnetic Resonance Imaging
Publisher
Elsevier
Publication Date
Jan 01, 1998
Volume
16
Issue
5-6
Pages
579–581
Identifiers
PMID: 9803913
Source
Medline
License
Unknown

Abstract

The diffusion coefficient for cyclohexane confined within pores of diameter 40 to 500 A has been measured as a function of temperature between 296 and 180 K, and is compared to values obtained for the bulk material. A substantial liquid-like signal is observed in the region of the depressed freezing points and a diffusion coefficient is measurable in all samples to well below these temperatures. The diffusion data appear to be continuous over the freezing region. These observations suggest persisting molten layers at interfaces which exchange with crystals forming within the silica pores. The diffusion coefficient of the molecules in the surface layer is three orders of magnitude larger than in the plastic phase of bulk cyclohexane.

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