PhD Position in Materials Science (M/F)

Job Description

Thesis Subject

Rheology and Hydration of Low-Carbon Silica-Magnesium Cements from Ultramafic Rocks.
Funding: European project Horizon Europe EIC-Pathfinder CONCERTO (https://concerto-eic.eu/)
1. Scientific context and objectives
Given the considerable carbon footprint of the cement industry, the development of alternative hydraulic binders is a major challenge for the ecological transition of construction materials. This PhD thesis is part of the European project CONCERTO (Horizon Europe EIC-Pathfinder), dedicated to the development of next-generation low-carbon hydraulic binders derived from ultramafic resources. The objective is to study the hydration mechanisms of silico-magnesian binders, from the very first dissolution reactions through to hardening and long-term mechanical performance. Particular attention will be paid to surface dissolution, nucleation and growth of hydrates, evolution of rheological properties, and to setting kinetics.
Two complementary strategies will be explored to control and accelerate hydration:
a) Effect of a mineral co-binder. The rapid dissolution of magnesium tends to generate silica-rich surface layers, passivating the reactive surface. The combination with a source of reactive alumina or silica (activated clays, aluminous residues such as aluminium-rich industrial by-products) will be studied in order to promote the formation of nucleating phases — magnesium silicates hydrates (M-S-H) or hydrotalcite-type phases acting as heterogeneous nucleation sites.
b) Control of iron reactivity by ligands. Iron, naturally present in silico-magnesian minerals, precipitates rapidly in the form of passivating oxyhydroxides in alkaline media. The use of chelating ligands, notably amines or of biological origin (extracts from bacterial cultures), will be explored to stabilise iron in solution and delay this passivation — an original approach at the chemistry–biology interface.
2. Methodology and experimental techniques
The multi-scale characterisation will combine:
Optical spectroscopies (FTIR, Raman) for the kinetic monitoring of structural transformations;
X-ray diffraction for the identification and monitoring of crystalline phases;
Solid-state NMR (²⁹Si, ²⁷Al) to probe the local coordination and polymerisation of silicon and aluminium, and to determine whether mechanical activation leads to separate Mg/Si phases or to a homogeneous solid solution;
X-ray absorption spectroscopy (XANES/EXAFS) like on the LUCIA beamline of the SOLEIL synchrotron, to follow in situ the evolution of the chemical environments of magnesium and iron.
Electron microscopy (SEM, TEM) for the morphology and spatial distribution of the phases;
3. Desired profile
Master's degree (or equivalent) in materials science, solid-state chemistry, chemical engineering or a related discipline. A strong interest in experimental research and complex multiphase systems with and an aptitude for interdisciplinary work. Experience in cement chemistry, solid-state characterisation, spectroscopy or synchrotron methods will be appreciated.

Your Work Environment

The PhD thesis will take place within the Paris-Saclay research cluster, between the LPS and LMPS laboratories, in an international and interdisciplinary environment underpinned by the European project CONCERTO. The doctoral student will benefit from access to advanced analytical platforms.
The Laboratoire de Physique des Solides is a joint research unit (UMR 8502) of Université Paris-Saclay and the CNRS. It is affiliated with the CNRS Institute of Physics and with the 28th section of the National Council of Universities. The LPS is a member of the Friedel-Jacquinot Federation, a structure coordinating physics research on the Moulon plateau in Orsay (Île-de-France).
It brings together around one hundred researchers and lecturer-researchers, both experimentalists and theoreticians, and research activities are supported by approximately sixty engineers, technicians and administrative staff.
The laboratory welcomes each year a large number of undergraduate and graduate students, including many doctoral students, as well as postdoctoral researchers and visiting scientists. The laboratory covers a broader range of topics than its name might suggest, and aims to address the full diversity of condensed matter physics. Research activities are organised around three main areas, each involving roughly the same number of scientists:
New electronic states of matter
Physical phenomena at reduced dimensions
Soft matter and the physics-biology interface
The first area brings together both experimental and theoretical studies relating to the properties of systems in which electronic correlations are generally strong, and which give rise to remarkable properties and unconventional electronic states such as superconductivity, magnetism, metal-insulator transitions, and so on.
The second area encompasses activities falling under "nanosciences" in the broad sense. These are addressed here from the perspective of fundamental properties, when the dimensions of an object become as small as certain characteristic length scales (coherence length, mean free path, etc.).
The third area extends the concept of "soft matter" to biological systems. Topics range from complex systems to living tissues, from liquid crystals to foams, and from polymers to granular systems. These physical studies sit at the interface with physical chemistry and biology.
The research underlying the proposed thesis will be conductedIt within this third area.
It should be noted that part of the work will be carried out at the LMPS (Laboratoire de Mécanique Paris-Saclay) of ENS Paris-Saclay.

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.

CNRS

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