We develop a phenomenological model for size-dependent anisotropic plastic deformation of colloidal nanoparticles under ion irradiation. We show that, at the nanoscale, nonhydrostatic capillary stresses drive radiation-induced Newtonian viscous flow, counteracting the stress state that initiates the anisotropic viscous strains in the high-temperature thermal spike region around the ion track. We present experimental data using colloidal silica nanoparticles in the 10-100 nm size range that show that the deformation is indeed strongly size dependent, in excellent agreement with the model. This work allows for the prediction of the ion-beam-induced shape modification of a whole range of nanostructures.

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Persistent URL dx.doi.org/10.1103/physrevb.74.132103
Journal Phys. Rev. B
van Dillen, T, van der Giessen, E, Onck, P.R, & Polman, A. (2006). Size-dependent ion-beam-induced anisotropic plastic deformation at the nanoscale by nonhydrostatic capillary stresses. Phys. Rev. B, 74(Article number: 132103), 1–4. doi:10.1103/physrevb.74.132103