Re-entrant melting and freezing in a model system of charged colloids
Abstract
We studied the phase behavior of charged and sterically stabilized colloids using confocal microscopy in a less polar solvent (dielectric constant 5.4). Upon increasing the colloid volume fraction we found a transition from a fluid to a body centered cubic crystal at 0.0415+/-0.0005, followed by re-entrant melting at 0.1165+/-0.0015. A second crystal of different symmetry, random hexagonal close-packed, was formed at a volume fraction around 0.5, similar to that of hard spheres. We attribute the intriguing phase behavior to particle interactions that depend strongly on volume fraction, mainly due to changes in the colloid charge. In this low polarity system the colloids acquire charge through ion adsorption. The low ionic strength leads to fewer ions per colloid at elevated volume fractions and consequently a density-dependent colloid charge.
Keywords
Cite
@article{arxiv.cond-mat/0512666,
title = {Re-entrant melting and freezing in a model system of charged colloids},
author = {C. Patrick Royall and Mirjam E. Leunissen and Antti-Pekka Hynninen and Marjolein Dijkstra and Alfons van Blaaderen},
journal= {arXiv preprint arXiv:cond-mat/0512666},
year = {2017}
}
Comments
25 pages, 5 figures 1 table