Energy dependent saturation width of swift heavy ion shaped embedded Au nanoparticles

The transformation of Aunanoparticles (NPs) embedded in SiO₂ from spherical to rod-like shapes induced by swift heavy ion irradiation has been studied. Irradiation was performed with ¹⁹⁷Au ions at energies between 54 and 185 MeV. Transmission electron microscopy and small angle x-ray scatteringmeasurements reveal an energy dependent saturation width of the NP rods as well as a minimum size required for the NPs to elongate. The NP saturation width is correlated with the ion track diameter in the SiO₂. NP melting and in-plane strain in the irradiatedSiO₂ are discussed as potential mechanisms for the observed deformation.P.K. and M.C.R. thank the Australian Research Council for support. P.K., R.G., D.J.S., and M.C.R. were supported by the Australian Synchrotron Research Program, funded by the Commonwealth of Australia via the Major National Research Facilities Program