%0 Book Section %1 statphys23_0855 %A Velasco, E. %A Martinez-raton, Y. %B Abstract Book of the XXIII IUPAP International Conference on Statistical Physics %C Genova, Italy %D 2007 %E Pietronero, Luciano %E Loreto, Vittorio %E Zapperi, Stefano %K crystals lamellar liquid matter phase soft statphys23 topic-7 %T Microsegregated lamellar-phase formation in liquid mixtures of hard rods and spheres %U http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=855 %X Many soft-matter systems exhibit partially-ordered phases known as lamellar phases, where molecular units are arranged in quasi two-dimensional layers that pile up to form extended phases. Therefore it is important to be able to formulate simple models that can help understand the mechanism involved in the formation of these structures. Models based on hard particles are ideal in this respect since only entropic effects are involved. The addition of small hard spheres to a fluid of hard rods which, when in pure form, can get stabilised into a smectic phase (such as a fluid of hard cylinders), is known to enhance the stability of the lamellar phase (where layers of hard rods and hard spheres alternate); these findings have been demonstrated by computer simulations and theoretical approaches on simple models that consider rods to be perfectly oriented. Here we show that even models which do not possess smectic order, such as hard ellipsoids of revolution, have a strong tendency to form lamellae when hard spheres are added in varying amounts. By defining particle models that smoothly interpolate between ellipsoidal and cylindrical shapes, the entropic mechanism governing these phenomena can be identified. These results are supported by Monte Carlo simulations together with density-functional theory, which also shed light on the possible occurrence of columnar ordering. Our analysis has allowed us to map out the phase behaviour of perfectly oriented mixtures of hard rods and spheres in terms of particle concentration, density and geometric shape.

@incollection{statphys23_0855, abstract = {Many soft-matter systems exhibit partially-ordered phases known as lamellar phases, where molecular units are arranged in quasi two-dimensional layers that pile up to form extended phases. Therefore it is important to be able to formulate simple models that can help understand the mechanism involved in the formation of these structures. Models based on hard particles are ideal in this respect since only entropic effects are involved. The addition of small hard spheres to a fluid of hard rods which, when in pure form, can get stabilised into a smectic phase (such as a fluid of hard cylinders), is known to enhance the stability of the lamellar phase (where layers of hard rods and hard spheres alternate); these findings have been demonstrated by computer simulations and theoretical approaches on simple models that consider rods to be perfectly oriented. Here we show that even models which do not possess smectic order, such as hard ellipsoids of revolution, have a strong tendency to form lamellae when hard spheres are added in varying amounts. By defining particle models that smoothly interpolate between ellipsoidal and cylindrical shapes, the entropic mechanism governing these phenomena can be identified. These results are supported by Monte Carlo simulations together with density-functional theory, which also shed light on the possible occurrence of columnar ordering. Our analysis has allowed us to map out the phase behaviour of perfectly oriented mixtures of hard rods and spheres in terms of particle concentration, density and geometric shape.}, added-at = {2007-06-20T10:16:09.000+0200}, address = {Genova, Italy}, author = {Velasco, E. and Martinez-raton, Y.}, biburl = {https://www.bibsonomy.org/bibtex/2d3f2a073cf1e5c09300cb1b4573a068b/statphys23}, booktitle = {Abstract Book of the XXIII IUPAP International Conference on Statistical Physics}, editor = {Pietronero, Luciano and Loreto, Vittorio and Zapperi, Stefano}, interhash = {1fe3e775dff6ff9eff28f1e5f5561848}, intrahash = {d3f2a073cf1e5c09300cb1b4573a068b}, keywords = {crystals lamellar liquid matter phase soft statphys23 topic-7}, month = {9-13 July}, timestamp = {2007-06-20T10:16:31.000+0200}, title = {Microsegregated lamellar-phase formation in liquid mixtures of hard rods and spheres}, url = {http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=855}, year = 2007 }