Regensburg 2000 – scientific programme
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DF: Dielektrische Festkörper
DF 7: Poster
DF 7.9: Poster
Thursday, March 30, 2000, 09:30–13:00, C
MELTING-FREEZING PHASE TRANSITION OF METALS IN POROUS GLASSES — •Thomas Loeser1, Dieter Michel1, and Elena Vladimirova Charnaya2 — 1Universität Leipzig, Fakultät für Physik und Geowissenschaften, Linne-Straße 5, 04103 — 2St. Petersburg Universität, Institut für Physik, 198904 St. Petersburg, Russia
Melting-freezing phase transitions of gallium within porous glasses and opals were studied by NMR. Various forms of confined metal may be differentiated due to the differences in the Knight shifts and the NMR intensity changes. A strong depression of the phase transition temperature and a pronounced hysteresis in the melting-freezing processes can be observed. The results can be explained on the basis of the Gibbs-Thompson equation, the geometric freezing model, and the formation of a liquid skin during the melting process in the pores. XRD, ultrasonic and resitance measurements are discussed for comparison.