Investigating Failure Criteria in Disordered Nanoparticle Packings

Nanoparticle packings have potential uses in new nanoscale devices including in optics, electronics, and biomedicine. Of particular significance to the design of these new devices is a thorough characterization of the mechanical behavior of nanoparticle packings. Previous work demonstrates that disordered materials undergo a jamming transition, where particles become fixed in place due to compressive loading. This transition has been reported as a strong function of density, stress, and temperature. Atomic force microscopy-based nanoindentation experiments were performed on disordered nanoparticle packings to determine the mechanical behavior of these material systems. Specifically, the plastic deformation and failure of disordered nanoparticle thin films was investigated below the jamming transition. Current directions include investigating how the mechanical behavior of the nanoparticle packings change when a compressive strain is applied to the film, and the jamming transition is approached. Compressive stress will be applied to the thin films using a novel fixture which uses a vacuum to bend the wafer into a concave geometry.