Results 1 - 1 of 1
Results 1 - 1 of 1. Search took: 0.015 seconds
[en] The morphology of latent ion tracks induced by high energy heavy ions in Al_2O_3 was investigated using a combination of high resolution transmission electron microscopy (HRTEM), exit wave reconstruction, geometric phase analysis and numerical simulations. Single crystal α-Al_2O_3 crystals were irradiated with 167 MeV Xe ions along the c-axis to fluences between 1 × 10"1"0 and 1 × 10"1"3 cm"−"2. Planar TEM lamella were prepared by focused ion beam (FIB) and geometrical phase analysis was performed on the phase image of the reconstructed complex electron wave at the specimen exit surface in order to estimate the latent strain around individual track cores. In addition to the experimental data, the material excitation in a SHI track was numerically simulated by combining Monte-Carlo code, describing the excitation of the electronic subsystem, with classical molecular dynamics of the lattice atoms. Experimental and simulation data both showed that the relaxation of the excess lattice energy results in the formation of a cylinder-like disordered region of about 4 nm in diameter consisting of an underdense core surrounded by an overdense shell. Modeling of the passage of a second ion in the vicinity of this disordered region revealed that this damaged area can be restored to a near damage free state. The estimation of a maximal effective distance of recrystallization between the ion trajectories yields values of about 6–6.5 nm which are of the same order of magnitude as those estimated from the saturation density of latent ion tracks detected by TEM.