High-throughput PVD deposition of semiconducting materials
Lead halide perovskites are a class of emerging semiconductors that have demonstrated considerable potential for utilization in solar cells.Nevertheless, the release of toxic lead into the environment during the lifespan of the cells is still a concern for their further commercialization.
This 24-months project aims at optimizing the deposition of lead-free double perovskite thin films for photovoltaic applications using PVD (Physical Vapor Deposition). The optimization of the material will be carried out by implementing high-throughput approaches in both the process and characterisation workflows.
Novel concentrated alloys (HEA/CCA) for nuclear applications: Corrosion and irradiation resistance in molten salts
This postdoctoral position is part of the national PEPR DIADEM program, within the DIAMS project, which aims to accelerate the discovery of new materials by combining computer design and experimental testing. The research focuses on materials for Molten Salt Reactors (MSRs), which require alloys that are resistant to both molten salt corrosion and irradiation. Certain optimized high-entropy alloys and complex concentrated alloys (HEA-CCA), offer superior performance compared to conventional materials such as austenitic stainless steels (ASS).
The postdoctoral research follows on an IA-based alloy design project carried out at IMN (Nantes), which identified promising compositions produced by conventional metallurgy and characterized after corrosion and irradiation on the JANNuS Saclay platform. The tests were carried out sequentially.
Starting in early 2026, the unique JANNuSel device will enable simultaneous corrosion and irradiation testing on both conventionally processed alloys and new compositions produced by AM (additive manufacturing) on the SAMANTA platform.
The samples will be analysed by SEM, TEM/EDX, EBSD, Raman spectroscopy, Atom Probe Tomography (APT), and synchrotron X-ray diffraction (MARS, SOLEIL) to understand the underlying mechanisms and optimize alloy properties.
The position is based at CEA Saclay, in close collaboration with IMN and Mines Saint-Étienne, and benefits from a rich interdisciplinary research environment.
Experimental and Thermodynamic Modeling of Corium Phases Formed During Severe Nuclear Accidents (24 months)
During severe accidents in pressurized water reactors, uranium dioxide (UO2) fuel reacts with zirconium alloy cladding and the steel vessel, forming a mixture of liquid and solid phases known as "in-vessel corium". If the vessel ruptures, this corium interacts with the concrete raft, forming "ex-vessel corium". This phenomenon occurred in the Chernobyl and Fukushima severe accidents. To simulate these stages, multi-physics codes require accurate thermodynamic and thermophysical data for the various phases of corium. This project aims to fill the data gap through experimental measurements and modeling. The work will involve synthesizing samples, measuring liquidus/solidus temperatures and liquid phase densities, and characterizing samples using advanced techniques. Moreover, the laser heating setup combined with aerodynamic levitation (ATTILHA) used to acquire data will be improved. Experimental results will be compared with thermodynamic models (TAF-ID database), and discrepancies will be resolved using the CALPHAD method. Thermophysical data will also be validated using atomistic simulations and other measurement techniques.
Impact of Storage Environment on the Aqueous Alteration of Iodate and/or Carbonate-Substituted Apatites for the Confinement of Long-Lived Radionuclides
Today, during the reprocessing of spent nuclear fuel, iodine-129 and carbon-14, two long-lived radionuclides, are managed through regulated discharge. The D-CLIC project, funded as part of the France 2030 actions, is an innovative project that aims to propose a method for conditioning iodine-129 and carbon-14 in the crystalline structure of phosphocalcic apatites. The qualification of this conditioning method is a scientific and environmental challenge. One of the objectives is to validate the long-term behavior of such matrices on inactive materials in environments that may be encountered at a future deep geological disposal site. The mission entrusted to the candidate will be to specify the alteration of these crystalline phases under saturated aqueous conditions for two types of environments, the first representative of the storage area for long-lived intermediate-level waste (ILW) and the second, representative of the storage area for high-level waste (HLW), as a function of different intrinsic and extrinsic parameters.
Accelerated development of materials resistant to molten chloride salts
The accelerated development of materials is a major challenge for all industries, and corrosion resistance is all the more important for resource conservation issues. This project therefore aims to estimate the corrosion resistance of FeNiMnCr alloys in chloride salt for use in molten salt nuclear reactors, in collaboration with the University of Wisconsin, which has demonstrated extensive expertise in the accelerated development of materials for molten fluoride and chloride salt reactors. As part of this post-doc, dozens of samples of quaternary FeNiMnCr model alloys will be synthesised by additive manufacturing at the University of Wisconsin, varying the composition in order to map the entire composition tetrahedron as accurately as possible. These samples, with a NiCr model alloy corroded in a wide range of molten chlorides salt chemistries, will then be corroded at the CEA. The aim of these experiments is, on the one hand, to obtain a large database on the corrosion of FeNiMnCr alloys in a very short time (1.5 years) and, on the other hand, to screen the effect of a wide range of salt compositions on a model NiCr alloy. Finally, these experiments will make it possible to target the best materials for studying their corrosion mechanisms.
Development of a capillary electrophoresis microsystem hyphenated to ICP-MS for isotopic and elemental analysis
The precise and accurate determination of isotopic and elemental compositions of samples by mass spectrometry is paramount in several research fields such as geoscience, environmental science, biology or the nuclear field. In order to avoid spectral or non-spectral interferences, it is necessary to perform chemical separations steps prior to analysis by mass spectrometry. In most cases, those separations are performed by liquid chromatography. Electrokinetic separation methods are particularly suitable to perform those separations due to the small volume of sample required and the small volume of waste produced, in the nL and µL range, respectively.
The main objective of this post-doctoral work is to integrate electrokinetic separations, presently performed in a glass capillary, in an analytical microsystem. This analytical microsystem, based on the microfluidic technology, will be used for the separation of elements and has to be hyphenated to an MC-ICP-MS without degrading the separation. The output of this work is an automated device capable of increasing throughput while keeping the same analytical performance as the original method. For nuclear samples, the device will reduce the dose received and the production of waste associated with the analytical protocol.
Understanding and modeling the thermodynamic and kinetic properties of MOX fuel in future reactors
This study is part of the Sodium-Cooled Fast Reactor projects. Uranium and plutonium dioxide (U,Pu)O2, known as MOX, is the reference fuel. During operation, fuel pellets are subjected to a high thermal gradient that induces mass transport, thermodiffusion, and vaporization phenomena, coupled with irradiation effects. Fuel performance codes are developed to simulate the behavior of fuel rods under nominal and incidental conditions, up to and including meltdown.
The objective of this study is to improve the thermokinetic model of MOX used in these codes. This model is based on the description of the U-Pu-O system using the CALPHAD method, coupled with a database of element mobilities developed using DICTRA software. The description of defects will be extended with the introduction of metal vacancies and oxygen clusters. The description of thermodynamic data (oxygen potential and heat capacity) and the phase diagram will also be improved by taking into account the most recent data. Finally, the mobility database, coupled with the Calphad model, will be improved to better describe diffusion in MOX. New experimental data as well as data calculated using atomic-scale calculation methods (molecular dynamics, ab initio) will be used.
Diamond-based electrochemical sensors for monitoring water pollution in urban environments
This postdoctoral position is offered by CEA List as part of the European UrbaQuantum project ("A novel, Integrated Approach to Urban Water Quality Monitoring, Management and Valorisation"), part of the HORIZON-CL6-2024-ZEROPOLLUTION-02 call for projects. The main objective of this project is to develop, in response to climate change, sensors, models, and protocols for better management of the water cycle in urban environments.
At the Sensors and Instrumentation for Measurement Laboratory (LCIM)of CEA List the postdoctoral fellow will contribute to the development of electrochemical sensors based on synthetic diamond and associated measurement protocols for the detection of pollutants such as pharmaceuticals, heavy metals, PFAS, and pesticides. These sensors will be miniaturized and integrated into a microfluidic cell, in partnership with CEA-Leti, then tested under real-world field conditions.
Solvothermal synthesis of carbon dots for optoelectronic applications
Carbon dots (C-dots) are nano-sized particles of carbon that exhibit unique electronic, optical and chemical properties due to their exceptional physico-chemical properties. These small, high surface-to-volume ratio materials are semiconductors that glow under irradiation, making them ideal for detecting ionizing radiation. Conventional plastic scintillators rely on energy transfer from the ultraviolet to visible light via organic fluorophores. The ability of CDs to absorb photons in the ultraviolet range and emit them in the visible range means that they could potentially replace organic fluorophores in their role as a bridge between ultraviolet and visible light. With low production costs, they can be synthesized either by conventional stepwise organic synthesis or, more rapidly, by top-down or bottom-up single-step approaches using a variety of chemicals. In this context, we have recently developed an interesting synthesis route enabling the preparation of C-dots emitting at different wavelengths, thus covering the entire visible range.