Doctorat (M/F) _ Synthesis of nanostructured iron nitrides, sustainable materials for applications in the energy sector.

Job Description

Thesis Subject

The iron nitrides are low cost and non-toxic materials, which can find many applications, especially at the nanoscale depending on their composition. For example, the nanostructured ε-FexN phase (x=2-3) can be used as electrocatalyst (in fuel cells or for hydrogen production), as electrode in high performance batteries, or for its magnetic properties in biomedical applications. Nanoparticles of the magnetically soft γ'-Fe4N phase are of huge interest for their microwave absorption properties. The hard α''-Fe16N2 phase could be used to build sustainable permanent magnets. The main route to these phases starts from the synthesis of iron oxide nanoparticles which are then reduced at high temperature and nitridated by exposure to ammonia. To avoid the first step, which is very energy consuming, we have developed a process based on the direct nitridation of zerovalent iron nanoparticles by ammonia. By this method, the ε-Fe2N phase has been obtained and fully characterized. Preliminary experiments also lead to mixed materials consisting in α-Fe and α”-Fe16N2 phases, or ε-Fe3N and γ'-Fe4N phases. However, controlling the composition of the final material remains challenging, in particular when targeting the synthesis of phases with low nitrogen content.
The objective of this three-year PhD project is to identify the key parameters governing the incorporation of nitrogen in the iron structure with the objective to tune the nitrogen content in the final material and produce phase-pure nanostructured iron nitrides in a rational way.
To do so, the reactivity of the zerovalent iron nanoparticles towards ammonia and the incorporation of nitrogen in the iron structure during the nitridation process will be studied down the atomic scale and in real time using in situ gas transmission electron microscopy (TEM). Based on the knowledge gained, phase-pure iron nitride nanomaterials of low nitrogen content will be prepared, characterized and assessed in the relevant applications. The project will therefore consist of four parts:
- In situ study of the reactivity of iron nanoparticles with ammonia to control the rate of nitrogen incorporation, which implies first the implementation of environmental TEM under ammonia atmosphere.
- Laboratory-scale synthesis of iron nitride nanomaterials
- Characterization of the nanomaterials obtained by the adapted analysis techniques such as: electronic microscopy, ICP analysis, XRD, magnetic measurements…
- Property evaluation with regards to the targeted applications

Your Work Environment

This thesis is part of the ANR INSITU project and will receive support from three laboratories: the Centre for Materials Development and Structural Studies (CEMES) and the Coordination Chemistry Laboratory (LCC) in Toulouse, and the Quantum Materials and Phenomena Laboratory (MPQ) in Paris. It will be co-supervised by Catherine AMIENS, from the LCC's 'Engineering of Metallic Nanoparticles' team (https://www.lcc-toulouse.fr/ en/engineering-of-metal-nanoparticles-team-l/ ) and Christian RICOLLEAU, from the 'Advanced Electron Microscopy and Nano-Structures' team at the MPQ laboratory (https://mpq.u-paris.fr/means/), in close collaboration with Marc RESPAUD, from the "Surfaces, Interfaces and Nano-Objects" group at CEMES (https://www.cemes.fr/sinano/). A collaboration with the Physical and Chemical Modelling team at the Laboratory of Physics and Chemistry of Nano-Objects will provide the modelling/theoretical calculations necessary for the project.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

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