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PhD subjects

5 sujets IRAMIS

Dernière mise à jour : 06-06-2020


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• Ultra-divided matter, Physical sciences for materials

 

Non-crystalline intermediate states during the setting of concrete: undesirable effect or opportunity to seize?

SL-DRF-20-1020

Research field : Ultra-divided matter, Physical sciences for materials
Location :

Service Nanosciences et Innovation pour les Materiaux, la Biomédecine et l’Energie

Laboratoire Interdisciplinaire sur l’Organisation Nanométrique et Supramoléculaire

Saclay

Contact :

Jean-Baptiste CHAMPENOIS

David CARRIÈRE

Starting date : 01-11-2020

Contact :

Jean-Baptiste CHAMPENOIS
CEA - DEN/DE2D/SEAD/LCBC

04 66 33 90 60

Thesis supervisor :

David CARRIÈRE
CEA - DRF/IRAMIS/NIMBE/LIONS

0169085489

Personal web page : http://iramis.cea.fr/Pisp/david.carriere/

Laboratory link : http://iramis.cea.fr/nimbe/lions

One of the great scientific and technical objectives of the century is the decommissioning of nuclear power plants. Today, in order to condition waste with low and intermediate activities, we use the common calcium-silicate cements. However, this approach faces two challenges: i) the fight against global warming imposes on cement industry to reduce its carbon footprint. We must therefore anticipate replacement with new generation cements, and ii) the effluents to be treated gain in complexity and variability. It is therefore necessary to improve the robustness of the cement formulations and their flexibility.

To meet these two challenges, this thesis will focus on a new generation of cements, and will aim to understand and master the mechanisms of crystallization even in the presence of external additives. The essential originality of this project is to take into account the non-crystalline transients states that form during the setting of cements. These non-crystalline transients states, unveiled very recently, seriously question the classical depiction of crystallization. In addition, they are suspected of favoring or disadvantaging the sequestration of effluents, depending on the case. This thesis will in particular make use of cutting-edge synchrotron experiments (ESRF, SOLEIL) to obtain structural characterizations at time and size scales relevant for crystal nucleation (<1s, <1nm).
Non-classical crystallization of materials for the environment: clarification of the amorphous-crystal relation by new generation synchrotron techniques.

SL-DRF-20-0572

Research field : Ultra-divided matter, Physical sciences for materials
Location :

Service Nanosciences et Innovation pour les Materiaux, la Biomédecine et l’Energie

Laboratoire Interdisciplinaire sur l’Organisation Nanométrique et Supramoléculaire

Saclay

Contact :

Corinne CHEVALLARD

David CARRIÈRE

Starting date : 01-11-2020

Contact :

Corinne CHEVALLARD
CEA - DRF/IRAMIS/NIMBE/LIONS

01-69-08-52-23

Thesis supervisor :

David CARRIÈRE
CEA - DRF/IRAMIS/NIMBE/LIONS

0169085489

Personal web page : http://iramis.cea.fr/Pisp/68/david.carriere.html

Laboratory link : http://iramis.cea.fr/nimbe/lions/

More : http://iramis.cea.fr/Pisp/78/corinne.chevallard.html

The formation of crystals by reactions in solution is involved in many natural and industrial processes, and in particular in the synthesis of materials of interest for the environment: nanostructured oxides for catalysis, oxalates for the recycling of rare earths, carbonates for the sequestration of atmospheric CO2.

In these applications, it is necessary to control the final crystals in terms of kinetics of formation, size (s), state of aggregation, and crystalline type in case of polymorphism. But the control of these processes is hampered because these crystallizations involve amorphous intermediates which are completely ignored by the usual theoretical guides (classical theories of nucleation / growth). The nature of the corrections to be brought to the conventional approaches is unclear since it is very difficult to measure the events during the reaction, from the initial ions, via the amorphous intermediates, to the final crystals, at sufficiently short time scales (<< ms) and sufficiently wide spatial scales (from Ångström to several tens of micrometers).

The objective of this thesis is to solve the knowingly difficult problem of measuring the non-classical crystallizations in water. The originality is to rely on the techniques now available thanks to the advent of fourth-generation synchrotrons: i) characterization of reaction times shorter by three orders of magnitude compared to the state of the art, achieving measurements in microfluidic fast mixers; and (ii) characterization at all spatial scales, with both resolutions and spatial expansions one to two orders of magnitude better than the state of the art, thanks to small angles X-ray scattering cartography.

SL-DRF-20-0570

Research field : Ultra-divided matter, Physical sciences for materials
Location :

Service Nanosciences et Innovation pour les Materiaux, la Biomédecine et l’Energie

Laboratoire Interdisciplinaire sur l’Organisation Nanométrique et Supramoléculaire

Saclay

Contact :

Valérie GEERTSEN

Patrick GUENOUN

Starting date : 01-09-2020

Contact :

Valérie GEERTSEN
CEA - DRF/IRAMIS/NIMBE/LIONS

0643360545

Thesis supervisor :

Patrick GUENOUN
CEA - DRF/IRAMIS/NIMBE/LIONS

01-69-08-74-33

Personal web page : http://iramis.cea.fr/Pisp/valerie.geertsen/

Laboratory link : http://iramis.cea.fr/nimbe/lions/

More : http://iramis.cea.fr/Pisp/daniel.bonamy/

The PhD proposal focuses on the design of a new class of metamaterials whose originality lies in both architecture and chemical formulation. These metamaterials take the shape of microarrays. They are therefore much lighter than solid materials. Their architecture is both random and hierarchical (bone structure inspired) to give them sufficient isotropic mechanical response and rupture resistance to consider their use as structural material. The architecture is defined and optimized by calculation within the framework of another thesis [SL-DRF-20-0591, proposed in the NUMERICS program] at the SPHYNX laboratory.

The innovative chemistry of this PhD study wants to give these new metamaterials typical nano-composites properties. This involves improving mechanical, thermal, neutron or fire resistance properties adding substantial quantities of boron-based nanoparticles. Foreseen applications are nuclear installation dismantling or waste transport. The study will focus on spherical B4C nanoparticles whose hardness and high boron content induces important neutrophage properties. The meta materials will be printed by stereolithography in the LIONS laboratory in close collaboration with the SPHYNX laboratory.

More precisely, the study will consist in grafting monomers on nanoparticle surface to optimize their dispersion in the polymer resin. It will also focus on the relationship between nanoparticle (composition, size, shape, content) and printed materials properties (mechanical, thermal, resistance to radiation). These new materials will be analyzed both in their massive and structured form. The PhD student will benefit from the LIONS laboratory expertise in nanoparticles synthesis and grafting, 3D printing and analytical techniques (SAXS, TEM access, ICPMS ...) and radiolysis study facilities. The (visco) elastic behavior, the crushing resistance and the rupture response will be characterized at the SPHYNX laboratory.

The student will also benefit from the interdisciplinary ecosystem created at LIONS and SPHYNX laboratories around the design of these new materials. He/she will learn from the presence of other doctoral students and trainees. This very interdisciplinary work (3D printing, photo-polymerization, nanoparticles, analysis, radiolysis, metallization ...) implies a taste for teamwork as well as an important scientific curiosity and an open mind. The highly instrumental aspect of the project requires also a taste for laboratory work and instrumentation. A polymer chemistry skill will be highly appreciated.

SL-DRF-20-0579

Research field : Ultra-divided matter, Physical sciences for materials
Location :

Service Nanosciences et Innovation pour les Materiaux, la Biomédecine et l’Energie

Laboratoire Interdisciplinaire sur l’Organisation Nanométrique et Supramoléculaire

Saclay

Contact :

Fabienne TESTARD

Antoine THILL

Starting date :

Contact :

Fabienne TESTARD
CEA - DRF/IRAMIS/NIMBE/LIONS

01 69 08 96 42

Thesis supervisor :

Antoine THILL
CEA - DRF/IRAMIS/NIMBE/LIONS

01 69 08 99 82

Personal web page : http://iramis.cea.fr/Pisp/antoine.thill/thill_fr.html

Laboratory link : http://iramis.cea.fr/nimbe/lions/

Development of a CVD plasma assisted process for the synthesis of spherical boron doped diamond core-shells and advanced characterizations toward photoelectrocatalysis

SL-DRF-20-1149

Research field : Ultra-divided matter, Physical sciences for materials
Location :

Service Nanosciences et Innovation pour les Materiaux, la Biomédecine et l’Energie

Laboratoire Edifices Nanométriques

Saclay

Contact :

Martine Mayne

Hugues GIRARD

Starting date : 01-10-2020

Contact :

Martine Mayne
CEA - DRF/IRAMIS/NIMBE/LEDNA

01 69 08 48 47

Thesis supervisor :

Hugues GIRARD
CEA - DRT/DM2I//LCD

0169084760

Personal web page : http://iramis.cea.fr/Pisp/martine.mayne/

Laboratory link : http://iramis.cea.fr/nimbe/ledna/

Boron Doped Diamond (BDD) emerges as an outstanding material for electrochemistry, electrocatalysis, photocatalysis and medicine. Among all these applications of BDD, one emerges as crucial in the current of climate change and concerns the recycling of CO2 through its re-use as useful chemicals and even fuels. Indeed, BDD has already been identified as an outstanding electrode for the electrochemical reduction of CO2. Furthermore, BDD has also been recently revealed as a solid source of solvated electrons in water, which opens the door to the selective CO2 into CO, not accessible with other materials. Both approaches, via pure electrochemistry or via photo-electro-chemical reduction, thus offer to BDD a great opportunity of development in the coming years. Individual nano or sub-micron objects made of BDD would be of great benefit for these applications. During this PhD, we propose a breakthrough approach, based on the synthesis of monodispersed spherical core/shell particles, starting from commercially available spherical cores of SiO2 and a shell of electrically conductive BDD of few tens of nm. We will develop an innovative CVD technology assisted by plasma dedicated to the individual coating of nanoµ particles with BDD, able to treat a large volume per batch (> 100 mg/h). Objectives of the thesis are (i) to design & develop a high production-yield synthesis reactor with a technology which could be upscaled afterwards ensuring uniformity and reproducibility of the diamond coating (ii) to qualify the structural quality of BDD shells and the overall microstructure by a panel of advanced analysis techniques (iii) to investigate and evidence the performances of BDD core-shells regarding electrochemical and photochemical properties before (iv) evaluate their performances toward CO2 reduction. This thesis will be held in the context of the ANR COCONUT project which gathers academic and industrial partners for strong collaborations.

 

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