Regensburg 2004 – scientific programme

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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.46: Poster

Thursday, March 11, 2004, 16:00–18:00, Poster D

PHASE BEHAVIOUR AND ELASTICITY OF COLLOIDAL MODEL SUSPENSIONS — •Larysa Shapran, Patrik Wette, Hans Joachim Schöpe, and Thomas Palberg — Johannes Gutenberg-University Mainz, Institute of Physics, Staudinger Weg 7, D-55099 Mainz

We have measured the phase behaviour and the elasticity of crystallizing systems of submicron polystyrene spheres in low salt aqueous suspension. Microscopy and static light scattering (SLS) yield the fluid-crystal transition lines including the coexistence region in the particle number density n salt concentration c plane. SLS shows further that the crystal phase is b.c.c. Torsional resonance spectroscopy [1] yields the static shear modulus G, which is observed to increase with n at constant c=0 and to decrease at n=const with increasing c. We compare our phase behaviour predictions from computer simulation [2,3] using the effective charge Z*(n,c) derived from the elasticity measurement. Use of the elasticity effective charge instead of previously often employed conductivity charge improves the consistency significantly.

[1] H.J.Schöpe, T.Palberg, J. Colloid Interface Sci. 234, 149-161 (2001)

[2] M.O.Robbins, K.Kremer and G.S.Grest, J. Chem. Phys. 88, 3286 (1988)

[3] E.J.Meijer and D.Frenkel, J. Chem. Phys. 94, 2269 (1991)