Ion-beam-induced plastic deformation in vitreous silica

Irradiation of metallic glasses with swift heavy ions induces anisotropic plastic deformation. Above an incubation fluence, the sample dimensions perpendicular to the ion beam grow whereas the sample dimension parallel to it shrinks in such a way that the mass density remains unchanged. Similar effects in the case of an insulating glass, namely vitreous silica, are reported here. The irradiating particles were 20Ne, 36Ar, 58Ni and 129Xe of kinetic energy 70, 151, 230 and 360 MeV, respectively. A large sample growth with anisotropy related to the ion beam direction was observed. An effective electronic stopping power threshold of ∼ 2.5 KeV/nm was found for this growth phenomenon. This is just below the threshold (∼4 KeV/nm) needed for creating etchable latent nuclear tracks. (author)