Recrystallization as the governing mechanism of ion track formation

Abstract

Response of dielectric crystals: MgO, Al2O3 and Y3Al5O12 (YAG) to irradiation with 167MeV Xe ions decelerating in the electronic stopping regime is studied. Comprehensive simulations demonstrated that despite similar ion energy losses and the initial excitation kinetics of the electronic systems and lattices, signifcant diferences occur among fnal structures of ion tracks in these materials, supported by experiments. No ion tracks appeared in MgO, whereas discontinuous distorted crystalline tracks of ~2nm in diameter were observed in Al2O3 and continuous amorphous tracks were detected in YAG. These track structures in Al2O3 and YAG were confrmed by high resolution TEM data. The simulations enabled us to identify recrystallization as the dominant mechanism governing formation of detected tracks in these oxides. We analyzed efects of the viscosity in molten state, lattice structure and diference in the kinetics of metallic and oxygen sublattices at the crystallization surface on damage recovery in tracks.