Fractal Substructure of a Nanopowder

TL;DR

This paper uses numerical simulations to study how repeated fragmentation and settling of a nanopowder lead to a fractal structure with specific properties, revealing insights into its density, correlations, and relaxation behavior.

Contribution

It introduces a two-dimensional model simulating nanopowder evolution, demonstrating the emergence of fractal substructures with scale-invariant properties.

Findings

Final packing density is independent of initial conditions

Structure remains fractal up to the fragmentation scale with a fractal dimension of about 1.7

Relaxation time scales linearly with the fragmentation size l

Abstract

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.