Observation of a shape-dependent density maximum in random packings and glasses of colloidal silica ellipsoids Export

@article{Sacanna2007, abstract = {We have measured the random packing density of monodisperse colloidal silica ellipsoids with a well-defined shape, gradually deviating from a sphere shape up to prolates with aspect ratios of about 5, to find for a colloidal system the first experimental observation for the density maximum (at an aspect ratio near 1.6) previously found only in computer simulations of granular packings. Confocal microscopy of ellipsoid packings, prepared by rapidly quenching ellipsoid fluids via ultra-centrifugation, demonstrates the absence of orientational order and yields pair correlation functions very much like those for random sphere packings. The density maximum, about 12\% above the Bernal random sphere packing density, also manifests itself as a maximum in the hydrodynamic friction that resists the swelling osmotic pressure of the ellipsoid packings. The existence of the density maximum is also predicted to strongly effect the dynamics of colloidal non-sphere glasses: slightly perturbing the sphere shape in a sphere glass will cause it to melt.}, author = {Sacanna, S. and Rossi, L. and Wouterse, A. and Philipse, A. P.}, citeulike-article-id = {5433514}, citeulike-linkout-0 = {http://dx.doi.org/10.1088/0953-8984/19/37/376108}, doi = {10.1088/0953-8984/19/37/376108}, journal = {Journal of Physics: Condensed Matter}, keywords = {packing, rod\_synthesis}, number = {37}, pages = {376108+}, posted-at = {2009-08-13 23:10:29}, priority = {2}, title = {Observation of a shape-dependent density maximum in random packings and glasses of colloidal silica ellipsoids}, url = {http://dx.doi.org/10.1088/0953-8984/19/37/376108}, volume = {19}, year = {2007} }

TY - JOUR ID - Sacanna2007 L3 - citeulike-article-id:5433514 N2 - We have measured the random packing density of monodisperse colloidal silica ellipsoids with a well-defined shape, gradually deviating from a sphere shape up to prolates with aspect ratios of about 5, to find for a colloidal system the first experimental observation for the density maximum (at an aspect ratio near 1.6) previously found only in computer simulations of granular packings. Confocal microscopy of ellipsoid packings, prepared by rapidly quenching ellipsoid fluids via ultra-centrifugation, demonstrates the absence of orientational order and yields pair correlation functions very much like those for random sphere packings. The density maximum, about 12% above the Bernal random sphere packing density, also manifests itself as a maximum in the hydrodynamic friction that resists the swelling osmotic pressure of the ellipsoid packings. The existence of the density maximum is also predicted to strongly effect the dynamics of colloidal non-sphere glasses: slightly perturbing the sphere shape in a sphere glass will cause it to melt. IS - 37 JF - Journal of Physics: Condensed Matter TI - Observation of a shape-dependent density maximum in random packings and glasses of colloidal silica ellipsoids VL - 19 SP - 376108 KW - packing KW - rod_synthesis AU - Sacanna, S AU - Rossi, L AU - Wouterse, A AU - Philipse, AP PY - 2007/// UR - http://dx.doi.org/10.1088/0953-8984/19/37/376108 ER -