The structural evolution of a nano-powder by repeated dispersion and settling can lead to characteristic fractal substructures. This is shown by numerical simulations of a two-dimensional model agglomerate of adhesive rigid particles. The agglomerate is cut into fragments of a characteristic size l, which then are settling under gravity. Repeating this procedure converges to a loosely packed structure, the properties of which are investigated: a) The final packing density is independent of the initialization, b) the short-range correlation function is independent of the fragment size, c) the structure is fractal up to the fragmentation scale l with a fractal dimension close to 1.7, and d) the relaxation time increases linearly with l.
@article{arxiv.0802.3416,
title = {Fractal Substructure of a Nanopowder},
author = {Thomas Schwager and Dietrich E. Wolf and Thorsten Poeschel},
journal= {arXiv preprint arXiv:0802.3416},
year = {2009}
}