Asynchronous melting of embedded metal nanoparticles and silica matrix for shape elongation induced by swift heavy ion irradiation

Although the mechanism of shape-elongation of nanoparticles (NPs) by swift-heavy-ion-irradiation is still under debate, melting and solidification of NPs for pico-second region by thermal spikes has been proposed as one of the processes involved. Elongation of high melting point (MP) NPs (vanadium, TMPbulk=1890 °C) and of low MP NPs (zinc, TMPbulk=420 °C) were compared under irradiation with 200 MeV Xe14+ ions. Irrespective of the large difference in their MPs, both the V and Zn NPs showed comparable elongation. The insensitivity of elongation to the MP can be explained by the asynchronicity of melting of the silica and the NPs.