8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Fri 911:10-14:00P1.45Lindemann criterion for nano-clusters and the glasstransitionAlexander Voronel 11 Tel-Aviv University, School of Physics, Tel-Aviv Univers., H. Levanon St., Ramat-Aviv,69978 69978, Tel-Aviv, IsraelMean square displacement (MSD) of atoms as a function of temperature undergoes a break nearglass-liquid transformation for all liquids which allow such measurements in this area [1, 2]. Thevalue of MSD at the point of this break roghly corresponds to a Lindemann criterion of melting[3, 4] for close packed structure. The glass state consists of nano-clusters of symmetries noncompatiblewith crystallization which ”melt” [5, 6] in accordance with this criterion at the temperaturemuch deeper than the corresponding melting point of the bulk. It gives to the glass-transition offragile liquids a second order transition pattern with its more symmetric phase situated at the lowertemperature. Such a pattern means that an upper phase (supercooled liquid) has a higher numberdegrees of freedom than a glass. It fits also to our heat capacity Cp, viscosity and inner frictionmeasurements of Se and Se-containing glasses [3, 4, 7, 8]. [1] C. A. Angell, Science, 267, 1924,(1995) [2] U. Buchenau, R. Zorn, Europhys. Letters, 18 (6), 523, (1992) [3] A. Voronel, V. Lusternik,POLIMAT, Grenoble, Jul. 7-9, (2004) [4] A. Voronel, V. Lusternik, 18-th Eur. Conf. Term.Prop. 31Aug. -4Sept. 2008, Pau, France. [5] Berry, R. S., Phases and Phase Changes of SmallSystems, in ”Theory of Atomic Molecular Clusters”, Springer Verlag, 1999. [6] YaokiZhou, M.Karplus, K. D. Ball, R. S. Berry, J. Chem. Phys. , 116, 2323, (2002). [7] E. Bormashenko, R.Pogreb, S. Sutovsky, V. Lusternik, A. Voronel, Infrared Physics and Technology, 43, 397, (2002).[8] Bormashenko E., Pogreb R., Sutovsky S., Sheshnev A., Lusternik V., Voronel A., Proceedingsof Spie - the International Society for Optical Engineering, 4970, 110, (2003).45