USAXS and XPCS studies of the structure and dynamics of aqueous high concentration nanocolloids of iron-based spinel oxides

High concentration, up to 50 vol.%, are commonly produced using massive addition of steric organic stabilizers, although “naked” nanoparticles are necessary in many applications. We synthesized novel electrolyte- and organics-free colloids of silver and metal oxide nanoparticles with concentrations on the order of 1 kg/L. Preliminary SAXS/USAXS experiments revealed that the Fe3O4 colloids form large clusters, having varying fractal dimensions affecting viscosity and other properties of the dispersions. Here, we propose to use time-resolved USAXS for studying the structure and dynamics of magnetite and ferrites nanocolloids as a function of nature and concentration of oxides, surface capping (citrates or phosphates of Li, Na, H) and temperature. The data will be compared with the rheology and electrochemistry of the colloids to understand particle interaction, clustering, (equilibrium) dynamics at various length scales, and prospects of their engineering and emerging applications.