Statistical Nature of Atomic Disorder in Irradiated Crystals

A. Boulle and A. Debelle
Phys. Rev. Lett. 116, 245501 – Published 16 June 2016
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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 γ=0.730.37 range, i.e., far from the commonly assumed Gaussian case (γ=2)]. 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 fDXRD to quantify the disordering. fDXRD is found to be consistent with both independent measurements using ion channeling and with molecular dynamics calculations.

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  • Received 14 January 2016

DOI:https://doi.org/10.1103/PhysRevLett.116.245501

© 2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

A. Boulle1 and A. Debelle2

  • 1Science des Procédés Céramiques et Traitements de Surface, CNRS UMR 7315, Centre Européen de la Céramique, 12 rue Atlantis, 87068 Limoges, France
  • 2Centre de Sciences Nucléaires et de Sciences de la Matière, Université Paris-Sud, CNRS/IN2P3, Université Paris Saclay 91405 Orsay, France

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Issue

Vol. 116, Iss. 24 — 17 June 2016

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