The heterogeneous distribution of the liquid phase in partially filled porous glasses and its effect on self-diffusion.
The spatial distribution of the liquid phase in a typical, partially filled, porous glass (VitraPor #5) has been examined with the aid of magnetic resonance microscopy and field gradient nuclear magnetic resonance diffusometry techniques. The correlation length of the material turned out to be long enough to permit the visualization of the microscopic heterogeneity of the material by magnetic resonance imaging. Contrasts are dominated by transverse relaxation depending on local filling degree, which in turn depends on local microstructure. The bimodal heterogeneity of the latter was also visualized by scanning electron microscopy. The effect of heterogeneity on an effective diffusion coefficient has been examined for polar (water) and nonpolar (cyclohexane) molecules.
Farrher
German
G
Sektion Kernresonanzspektroskopie, Universität Ulm, 89069 Ulm, Germany.
Ardelean
Ioan
I
Kimmich
Rainer
R
D003510:Cyclohexanes; D004058:Diffusion; D005583:Fourier Analysis; D005898:Glass / Q000737:chemistry*; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008855:Microscopy, Electron, Scanning / Q000379:methods; D016062:Porosity; D014867:Water / Q000737:chemistry
D003510:Cyclohexanes; D014867:Water; C506365:Cyclohexane