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.
Robust path-following solvers for the finite element simulation of cracking in complex heterogeneous media: application to reinforced concrete structures
Path-following (or continuation) procedures are used to describe the unstable responses of structures exhibiting snap-back or snap-through phenomena. These methods consist in adapting the external load during the deformation process in order to satisfy a control constraint, by introducing an additional unknown, the load multiplier. Several variants exist depending on the controlled quantity: degrees of freedom, strain measures, or variables related to energy dissipation.
In addition to enabling the tracing of unstable responses, a major advantage of these approaches lies in improving the convergence of incremental Newton-type solvers by reducing the number of iterations required. This gain often compensates for the additional computational cost associated with the continuation algorithm. Some formulations have proven both efficient and simple to implement.
However, no objective criterion yet allows one to determine which formulation is best suited for the simulation of reinforced concrete structures, where multiple dissipation mechanisms coexist along with a strong spatial variability of the material properties.
The proposed postdoctoral work aims to develop robust path-following algorithms for such structures, building upon previous research carried out at CEA. It will include a critical analysis of existing formulations, an evaluation of their performance (monolithic or partitioned solvers), followed by their implementation. Finally, representative test cases of industrial structures will be simulated to assess the gain in robustness and computational cost compared to standard solvers.
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.
TOMOGLASS: Gamma Emission Tomography Applied to the Radiological Characterization of Glass Residues from the Cold Crucible Vitrification Process
The TOMOGLASS project aims to develop an innovative gamma tomography system capable of operating in high-activity environments to characterize in three dimensions the glass residues resulting from the vitrification process of nuclear waste. The objective is to precisely locate platinum-group inclusions, which are poorly soluble in glass, in order to improve the understanding and control of the process. The system is based on a compact gamma imager integrating high-resolution pixelated CZT detectors, pinhole-type collimation, and mounting on a robotic arm. It will enable multi-isotopic reconstruction using advanced tomographic algorithms. This project is part of the modernization of the La Hague facilities and the integration of digital technologies within the framework of the factory of the future.
The first phase of the project will consist in demonstrating the feasibility of implementing a spectro-imager prototype in a constrained environment, building on existing technological components: detection modules and acquisition electronics based on the HiSPECT technology, and image reconstruction algorithms developed at CEA-Leti. The work will focus on conducting a multi-parameter study through numerical simulations (Monte Carlo calculation code) to design an optimized measurement system, and to generate simulated datasets for various representative measurement configurations. Once the concept has been validated, the work will continue in year N+1 with the assembly of the prototype components and their integration on a robotic arm. Experimental tests may then be carried out to demonstrate the system in a representative environment.
Lithium ion Domestic Batteries recycling : Development and understanding of a new deactivation concept
Domestic lithium-ion batteries gather all batteries used in electronic devices, mobile phone, and tooling applications. By 2030, the domestic lithium-ion battery market will increase up to 30%. These lithium-ion batteries contain critical raw materials such as Nickel, Cobalt, lithium. With the new European recycling regulation (need to recover high % of Ni, Co, Cu, Li in 2031) and the emergency to find greener and safer recycling process (avoid thermal treatments currently used), it is today necessary to develop new deactivation process of domestic lithium-ion batteries.
The deactivation process is the 1st step of the recycling process and the aim is to remove all cell energy. It has to address several lithium-ion chemistries, be continuous, safe, controllable and low cost.
We propose a new electrochemical based concept (on going patent). The objective is to develop and understand the electrochemical mechanisms of this new deactivation concept of lithium ion domestic batteries
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.