Workplace: Institut de Matériaux, Microélectronique et Nanosciences de Provence (IM2NP), Campus Saint Jérôme, Case 142, 13397 Marseille Cedex 20, France
Type of contract: PhD contract
Contract duration: 36 months
Expected date of employment: January 2022
Working hours: full time
Remuneration : 1768.55 € gross/month (or 1421.39€ net)
Education level: master or engineer degree, in materials Science or applied physics.
Experience: internships in the field of materials science or applied physics.
Keywords: solidification ; faceted systems ; interface structure ; in situ observation.
Work context : The PhD student will work under the supervision of Drs. Fatima L. Mota, Nathalie Bergeon and Nathalie Mangelinck-Noël, within the "Microstructures de Croissance Auto-organisées" (MCA) team of IM2NP.
The proposed thesis project is part of the MATHIFA (Mechanism Analysis during THIck samples solidification of FAceted systems) project funded by the National Agency for Research (ANR, fr: Agence Nationale de la Recherche) whose coordinator is Dr. Mota.
Solidification proceeds by the propagation of the interface between the liquid phase and the growing crystal. The formation of growth microstructures at this solid-liquid interface during the elaboration of materials is a dynamic process in which a pattern develops, organizes and orders itself progressively. The in-depth knowledge of this dynamic constitutes a major challenge for the solidification mechanism modelling and for the optimization of predictive simulation tools capable of controlling elaboration processes and the final properties of strategic materials. The use of transparent organic alloys, whose solidification behavior is similar to that of materials in use, but which allow in situ and in real time observation by optical microscopy, is a major experimental approach for this type of study.
The interface dynamics differs depending on the attachment kinetics of atoms at the interface. In most metallic compounds, the kinetics is rapid and the solidification is basically governed by the heat and solute redistribution by diffusion. However, there are lots of materials (semi-conductors such as silicon, minerals, proteins, etc.) for which the interface presents faceted growth. This type of growth is associated to a finite undercooling via step-flow mechanisms, and is tributary to crystallographic defects that can act as sources of elementary steps. The solidification of materials with a faceted morphology during growth, the control of which is a major practical issue, remains little known and poorly understood.
The main objective of the thesis is to make major breakthrough on the analysis of solidification mechanisms of faceted materials. The main part of the studies will be carried out in the ECODIS device (Experimental setup for COnfined DIrectional Solidification) recently developed by the MCA team. This device allows in situ and real time observation of the solidification interface of transparent systems in thin sample geometry (quasi-2D growth). The studies could eventually be continued in a device dedicated to directional solidification of massive samples (3D growth), also available in the laboratory. The transfer from 2D to 3D imposes additional constraints in the selection of suitable transparent faceted alloys. Different alloys will be tested and evaluated, from the point of view of solidification but also of implementation criteria. The main tasks of the PhD student will include:
- The selection and characterization of transparent faceted alloys. A pre-selection of systems has been made beforehand but it will be refined and completed by the characterization of elements of the phase diagram.
- The preparation and realization of faceted systems solidification experiments with in situ and real time observation of the interface.
- The analysis of the experiments: interface formation, evolution and organization; grain competition; defect formation and evolution; effect of confinement. For this last point, studies with various sample thicknesses are foreseen.
- The comparison to silicon growth experiments studied by X-ray imaging and phase-field model simulations.
The PhD candidate must have a strong background in materials science and physico-chemistry of solids, and very good experimental skills. A knowledge of numerical programming would be appreciated. He/she should be motivated by research, be autonomous but able to work in a team, have a critical mind, be able to communicate in French and English (meetings, conferences) within the national and international collaborations of the project.
IM2NP is a joint research unit (UMR 7334) under the triple supervision of the Centre National de la Recherche Scientifique (CNRS), Aix-Marseille University (AMU) and the University of Toulon (UTLN). This large multidisciplinary institute, with about 300 people, is structured in 17 research teams gathered in 5 scientific departments which cover the whole chain of knowledge, from basic sciences (solid state physics, materials science) to devices, circuits and systems. The MCA team is specialized in the analysis of fundamental mechanisms and dynamic processes involved in the formation, selection and stability of solidification microstructures, segregation, grain structure and defects, in relation to the issues raised by industrial processes.
Applicants are invited to send a CV, a cover letter with the names of 2 referees, and university transcripts (master or engineering degree) to: Fatima L. Mota, email@example.com, Nathalie Bergeon, firstname.lastname@example.org and Nathalie Mangelinck-Noël, email@example.com.Meer informatie
|Titel||3-year-PhD contract offer: subject “In situ study of the directional solidification of transparent organic alloys with a faceted interface”|
|Job location||Jardin du Pharo 58, bd Charles Livon, 13284 Marseille|
|Gepubliceerd||juli 21, 2021|
|Vakgebieden||Experimentele fysica,   Materiaalchemie,   Fysische chemie,   Solid-state chemie,   Materiaalfysica,   Solid-state Physics,   Toegepaste fysica  |