Atomic force microscopy and cross-sectional transmission electron microscopy are used to characterize the evolution of nanoparticle/substrate interfaces during heavy-ion bombardment. Pt nanoparticles, prepared by annealing 3 Å Pt films on SiO 2, embed into the substrates following 800 keV Kr + irradiation. For Pt particles with diameters 5-20 nm, the depth of the embedding increases with an ion dose until the particles are fully submerged at a dose of ∼10 16cm -2. The results are explained by capillary driving forces and an ion-induced viscous flow of amorphous SiO 2. The irradiation-induced viscosity of SiO 2 needed to explain our results is ∼0.9×10 23Paioncm -2, consistent with previous measurements using stress relaxation. Similar results are obtained for 10 keV He + irradiation, suggesting that ion-induced viscosity arises from localized defects rather than from the creation of large melt zones. The embedding of Pt particles is inhibited, however, for energetically unfavorable substrates such as alumina.
ASJC Scopus subject areas
- Physics and Astronomy(all)