Regensburg 2002 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 3: Gl
äser I (gemeinsam FV DF/DY)

DF 3.3: Vortrag

Dienstag, 12. März 2002, 10:25–10:40, 23

Glass Transition in charged colloidal model system: A different route into the amorphous state? — •Hans Joachim Schöpe and Thomas Palberg — Institut für Physik, Universität Mainz, Staudinger Weg 7, D - 55099 Mainz, Germany

Colloidal suspensions have acquired a model system status in experimental research on the fundamentals of the glass transition and the glassy state. Most work so far was performed on hard sphere suspensions. Here we review experiments on charged spheres to observe a quite different scenario and route into the amorphous state. We find an approximately exponential increase of the nucleation rate density J: a competition between crystallisation and vitrification results. At low particle density crystals are generated through nucleation and growth. At large densities the nucleation rates become large enough leading to interactions between nuclei and an abortion of solidification before large crystals are formed. Above some critical density the resulting ordered regions consist of only very few particles and are comparable in size to density fluctuations in the melt. Here we identify an amorphous state of short range order, frozen large scale motion and finite shear modulus. Thus an amorphous state is kinetically stabilised via a different route as compared to hard spheres.