Simulations of Cracks Supported by Experiments: The Influence of the Film Height and Isotropy on the Geometry of Crack Patterns

Abstract

Here, we show that cracks give valuable information on the height and the isotropy of nanocrystal films. Two-dimensional crack patterns are systematically studied by simulations and experiments varying the height and the anisotropy of the applied stress. The simulations are carried out using a bundle-spring network model, which allows studying the influence of height on crack patterns. For the experiments, a model system made of magnetic γ-Fe2O3 nanocrystals is used, which enables a change in the anisotropy of the stress by applying a magnetic field during the drying process. The crack pattern morphology is investigated by simulations using square, hexagonal, and isotropic spring arrangements and applying an isotropic or unilateral stress. The average crack distance as a function of the film height studied by simulations follows a universal scaling law, confirming the experimental data. We show that this implies that the morphology of the crack pattern does not change with the height. The frequency of cra...