We report small-angle x-ray scattering (SAXS) experiments on aqueous dispersions of colloidal silica with a broad monomodal size distribution (polydispersity 18%, size 8 nm). Over a range of volume fractions the silica particles segregate to build first one, then two distinct sets of colloidal crystals. These dispersions thus demonstrate fractional crystallization and multiple-phase (bcc, Laves AB2, liquid) coexistence. Their remarkable ability to build complex crystal structures from a polydisperse population originates from the intermediate-range nature of interparticle forces, and suggests routes for designing self-assembling colloidal crystals from the bottom-up.
@article{arxiv.1511.02493,
title = {Hiding in plain view: Colloidal self-assembly from polydisperse populations},
author = {Bernard Cabane and Joaquim Li and Franck Artzner and Robert Botet and Christophe Labbez and Guillaume Bareigts and Michael Sztucki and Lucas Goehring},
journal= {arXiv preprint arXiv:1511.02493},
year = {2016}
}