Hard X-ray nanotomography of jammed sphere packings

Packing structures of spheres in three dimensions is important in understanding arrangement and geometry of pours media, metallic glasses, colloidal particles, and granular matter. Most theory and analysis are focused on random packing structures at large scale, while X-ray tomographic observations of colloidal particles on micro- and nanoscales are rare. Here we demonstrate jammed packings of colloidal microparticles with X-ray nanotomography. Projected images of jammed microparticles prepared by centrifuging colloidal suspensions are recorded and reconstructed to three-dimensional structures. Analysis of individual particle positions and pare correlation functions would help the nature of packing structures of colloidal particles. We believe that hard X-ray nanotomography would be a powerful tool to visualize and identify the packing systems that consist of colloidal particles.