RESUMO
We study the self-assembly of branching-chain networks and crystals in a binary colloidal system with tunable interactions. The particle positions are extracted from microscopy images and order parameters are extracted by image processing and statistical analysis. With these, we construct phase diagrams with respect to particle density, ratio and interaction. In order to draw a more complete picture, we complement the experiments with computer simulations. We establish a region in the phase diagram, where bead ratios and interactions are symmetric, promoting percolated structures.
RESUMO
Colloidal systems offer unique opportunities for the study of phase formation and structure since their characteristic length scales are accessible to visible light. As a model system the two-dimensional assembly of colloidal magnetic and non-magnetic particles dispersed in a ferrofluid (FF) matrix is studied by transmission optical microscopy. We present a method to statistically evaluate images with thousands of particles and map phases by extraction of local variables. Different lattice structures and long-range connected branching chains are observed, when tuning the effective magnetic interaction and varying particle ratios.
RESUMO
Self-assembly is one of the most fascinating phenomena in nature and is one key component in the formation of hierarchical structures. The formation of structures depends critically on the interaction between the different constituents, and therefore the link between these interactions and the resulting structure is fundamental for the understanding of materials. We have realized a two-dimensional system of colloidal particles with tunable magnetic dipole forces. The phase formation is studied by transmission optical microscopy and a phase diagram is constructed. We report a phase transition from hexagonal to random and square arrangements when the magnetic interaction between the individual particles is tuned from antiferromagnetic to ferrimagnetic.
