Abstract
Atomic disorder in irradiated materials is investigated by means of x-ray diffraction, using cubic SiC single crystals as a model material. It is shown that, besides the determination of depth-resolved strain and damage profiles, x-ray diffraction can be efficiently used to determine the probability density function (PDF) of the atomic displacements within the crystal. This task is achieved by analyzing the diffraction-order dependence of the damage profiles. We thereby demonstrate that atomic displacements undergo Lévy flights, with a displacement PDF exhibiting heavy tails [with a tail index in the range, i.e., far from the commonly assumed Gaussian case ()]. It is further demonstrated that these heavy tails are crucial to account for the amorphization kinetics in SiC. From the retrieved displacement PDFs we introduce a dimensionless parameter to quantify the disordering. is found to be consistent with both independent measurements using ion channeling and with molecular dynamics calculations.
- Received 14 January 2016
DOI:https://doi.org/10.1103/PhysRevLett.116.245501
© 2016 American Physical Society