Development of explosive compositions using RAM acoustic technology
The objective is to develop, at the laboratory scale, formulations consisting of one or more energetic molecules and a binder. These materials must match the specifications in terms of performance and insensitivity.
This new process using acoustic waves is an innovative and very promising method for rapidly obtaining new explosive compositions with optimized properties. The work will therefore consist of:
- Conducting a bibliographic review to obtain formulations in granular form using the RAM (resonant acoustic mixing) process.
- Identifying the various process parameters and understanding their influence on the final properties of the mixture.
- Formulating energetic compositions on a laboratory scale that match the specifications.
- Characterizing the materials produced through physicochemical analyses.
- Proposing improvements to optimize the final properties.
- Proposing new applications for RAM in connection with the unit's activities.
Synthesis of high-nitrogen heterocyclic molecules
One of the CEA DAM's objectives is the design of new explosive compositions with optimized properties. As such, the search for new molecules of interest, likely to be integrated into innovative formulations, is a fundamental activity.
The objective of the post-doctorate is to synthesize, on a laboratory scale, energetic molecules with structures capable of meeting the specifications in terms of performance and insensitivity. These are mainly highly nitrogenous heterocyclic molecules (pyrazoles, triazoles, oxadiazoles, etc.). The work will include both the synthesis of intermediates, whether they are considered energetic or not, and that of the final products.
This approach is supported by modeling work carried out upstream, intended to set up tools to propose new structures and evaluate their properties by calculation. This subject will require, in interaction with the modeling team, using these tools and putting them to good use to guide the choice of targets that will be studied experimentally in the laboratory.
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.
Development of new Potassium-ion cells with high performances and low environmental impact
Lithium ion batteries are considered as the reference system in terms of energy density and cycle life and will play a key role in the energetic transition, especially concerning electric vehicles. However, such a technology involves the use of a large amount of critical elements and active materials are synthesised using energy intensive processes.
In this way, our team is developing a new Potassium-ion batteries technology with high performances but with a low environmental impact.
For this innovative and ambitious project, CEA-LITEN (one of the most important research institute in Europe) is looking for a talented post-doctoral researcher in material chemistry. The post-doctoral position is opened for a young researcher with a high scientific level, interested by valorising her/his results through different patents and/or scientific publications.
Experimental and technological developments of a process for the mineralization of organic liquid waste by plasma
The ELIPSE process developed at the CEA allows the destruction of organic liquids by injection into a high-power plasma.
If the feasibility of destroying different organic components at flow rates of a few liters per hour has now been demonstrated, tests must now be further developed for reference organic liquids appropriately chosen according to existing deposits.
These studies, based on the characterization data of the chosen LORs, will aim to provide detailed process results obtained with the most representative operating conditions, to allow a complete and quantitative evaluation of the process. This will make it possible to establish operating, robustness and endurance data for the process.
This work will include the study of the behavior of radioelements in the process, which will be essential for the nuclearization study: this will involve studying the physico-chemical behavior of actinides during their processing via the use of inactive simulants.
Thermodynamic investigation of Metal-Insulator-Transition materials – The case of doped VO2 for smart windows applications
The present post-doc proposal aims to develop a specific thermodynamic database on the V-O-TM (TM=Fe,Cr) system by using the CALPHAD approach. The candidate will conduct experimental campaigns to obtain relevant data to feed the thermodynamic models. The candidate will mostly use the experimental equipment available at the lab (DTA, annealing furnaces, high temperature mass spectrometry, laser heating, SEM-EDS). In addition, the post-doc may participate to combinatorial high-throughput activities led by other laboratory of the Hiway-2-Mat consortium (e.g., ICMCB in Bordeaux), allowing a better connection between the CALPHAD simulation output and the accelerated characterization platform. The thermodynamic database will be then included in the autonomous research routine implemented in the material exploration path.
Modelling of uranium precipitation kinetics as a function of pH. Application to fluidized bed reactor
The Orano plant in Niger (Somaïr) precipitates its uranium concentrate in a fluidized bed reactor by adding sodium hydroxide. The concentrate obtained contains around 6% sodium which leads to converter penalties. Orano carried out tests at the end of 2019 on a fluidized bed in the laboratory to change the operating point of precipitation and preferentially form UO3 via a change in pH. To refine the management of the industrial unit, it is necessary to model the precipitation reactions of uranium. The candidate will have to propose and calibrate a competitive precipitation model for Na2U2O7 and UO3 based on the equilibrium constants and reaction kinetics, as a function of the pH within the reactor. In particular, the model should make it possible to understand the impact of pH on the distribution of the two main species identified in the concentrate: Na2U2O7 and UO3. This chemical model should serve as input to an existing physical model of the fluidized bed reactor. An extension of the model to other precipitation reagents, in particular magnesia, could also be studied.
Synthesis and structural analysis of reference uranium minerals for the identification of uranium-bearing phases in mining environment by TRLFS.
In the frame of the collaborative project between the ICSM , CEA and Orano, a study is conducted in order to detect and identify minerals containing uranium (VI) by Time-Resolved Laser Fluorescence Spectroscopy (TRLFS). This technique showed its efficiency in order to identify the presence of uranyl in natural assemblies through the probing of the local environment of uranium. However, it requires the establishment of a database from synthetic and natural samples fully characterized. Therefore, in order to achieve this goal, we intend to synthesis, and thoroughly characterize a variety of compounds containing uranyl groups within the crystal structure. We can cite the families of oxi-hydroxide, sulfate, and silicates based compounds. Then, TRLFS spectra will be collected in order to complete the database and to evidence the impact of the local structure of uranyl cation on the intensity and the position of the emission bands. The obtained data will be also compared to a collection of natural samples.
Leaching foams to extract metals from electronic waste
The subject is part of the ANR "Foamex" project covering TRL from 1 to 5 and focussing on the development of recycling of some metals from a shred of electronic cards, this recycling being carried out in a fluid foam (minimization of the volume of solvents) that can be considered at the first level as a dynamic chromatography column. The principle is to use the foam as a reservoir containing an acid solution and specific oxidizing agents to dissolve and extract metals in the form of ionic species, a phenomenon enhanced by friction between bubbles and simultaneously to concentrate them via the fluid and mobile liquid/air interfaces by flow.