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Reference : UMR8609-REJBOD-011
Workplace : ORSAY
Date of publication : Friday, January 10, 2020
Scientific Responsible name : Aurélien DEBELLE
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 February 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Ion beams are nowadays currently used in numerous fields of material science: to tailor material physical properties (e.g. by doping semiconductors), to shape the materials (e.g. creation of porous structures) or to submit materials to harsh conditions aiming at reproducing those encountered in real situation (e.g. in space or in nuclear reactors). If the technical aspects of the use of ion beams are mastered, the understanding of the basic mechanisms of the ion/solid interactions is far from being optimal.
Conducting fundamental studies on model systems, using powerful characterization techniques, constitutes one approach to tackle this issue. But it requires, to get significant insights into the studies phenomena, to finely and accurately use and analyze the experimental data. Two techniques are available and mastered at the CSNSM: Rutherford backscattering spectrometry in channeling configuration (RBS/C) and X ray diffraction in high-resolution mode (HR-XRD). Both techniques allow quantifying the irradiation-induced disorder. However, the exact definition of this parameter varies from one material to the other and for the different techniques. Moreover, ascribing the disorder parameters to an actual microstructure usually depends on phenomenological models.
A recent work has shown that this disorder can be described with a statistical approach . This description could very likely be applied to other materials and to other techniques such as the RBS/C. For this purpose, a systematic study of a few selected materials is required. Besides, the description of irradiation defects at the atomic scale is now possible using dedicated computational methods (such as molecular dynamics techniques), and defect evolution at higher time and length scales can be captured using e.g. cluster dynamics simulations. Coupling these methods with experimental tools allows a better understanding of the defect generation mechanisms and of the subsequent evolution of the defects [2,3]. One step further in this approach is to develop dedicated modelling tools to generate (XRD and RBS/C) spectra from using computational data as input parameters.
The aim of the PhD will be to increase the body of knowledge in the understanding of the irradiation-induced (micro ) structural changes by conducting a combined experimental / computational study on the basis of the abovementioned framework. The candidate will have the opportunity to tackle both sides of this work, or to give his/her preference to one part. He/she will be in contact with researchers from other groups in France and in different countries (Finland, Poland, USA).
The PhD student will integrate the Materials and Irradiation Research group, which aims at studying, at different scales and with various experimental and numerical tools, ion/solid interactions. It benefits from the irradiation platform SCALP.
Constraints and risks
Required skills and knowledge: the candidate must be comfortable with the English language; he/she should have a significant background in materials science; experience in XRD or RBS, and/or in programming, and basic knowledge in ion/solid interactions would be appreciated.
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