Postdoc (M/F) in cristallochemistry of critical metalloids in mine wastes

Job Description

Missions

This project is part of the ANR REXEL program (Reconciling EXploitation of mineral resources and Environmental protection: natural attenuation and system resiLience), which aims to analyze the spatio-temporal evolution of waste from a former mining site that has been subject to weathering and erosion for 60 years. One of the main objectives is to acquire fundamental knowledge about the processes controlling environmental risks related to the dynamics of metal contaminants (speciation, geochemistry) dispersed by different vectors and their fate in the surrounding ecosystems to be preserved (water, soil, sediments).

Activity

The postdoctoral researcher will study the phases/mineraloids containing As, Bi, and W, from their primary form to their secondary or even tertiary form, in order to identify features of alteration and/or stability and the various stages leading to stable authigenic forms under supergene conditions. The study of such phases faces analytical challenges related to the size of the mineraloids, most of which measure approximately 3 to 1 µm or less, limiting the accuracy of analyses performed using conventional techniques. While mineralogical data already exist for the materials at the study site, little spectroscopic data (or none at all for certain elements) has been acquired concerning the local coordination environments and oxidation states of As, and even less for Bi & W. These objectives will be achieved using fine mineralogy and crystal chemistry techniques combining X-ray diffraction and pair distribution function analysis, infrared spectroscopy, and µ-Raman spectroscopy. Chemical mapping and phase speciation will be evaluated by fluorescence and X-ray absorption spectroscopy on a synchrotron with submicrometric spatial resolution. Spectroscopic data on As, Bi and W will be collected in order to determine their local coordination environment and oxidation state. In order to evaluate the probability/affinity and retention mechanisms of “metals” in carrier phases, an original approach of this project will consist in reproducing a series of synthetic alunite-type phases AB3(XO4)2(OH)6 by varying the composition of crystallographic sites A (K, Bi), B (Fe, Al), and X (As, S, P). These model phases will be synthesized hydrothermally. After characterization, the sorption/desorption of As, Bi, and W elements will be evaluated using static and/or dynamic leaching tests, with the solutions analyzed by ICP-MS. Selective extractions will be used to supplement the mineralogical data on the distribution of As, Bi, and W in different fractions that are more or less mobile depending on changes in the physicochemical parameters of the environment. All of these results will provide a better understanding of the mechanisms controlling the mobility and/or potential immobilization of metals in natural systems and a better understanding of in situ reaction kinetics.

Your Profil

Skills

The candidate must hold a PhD in physical chemistry or geosciences, with expertise in crystal-chemistry and/or geochemistry. Experience in inorganic mineral synthesis and analytical chemistry would be appreciated. He/she must be motivated by experimentation and possess organizational skills.

Your Work Environment

The Solid State Physics Laboratory is a joint research unit (UMR 8502) of Paris-Saclay University and the CNRS. It is affiliated with the CNRS Institute of Physics and the 28th section of the National Council of Universities. The LPS is a member of the Friedel-Jacquinot Federation, a physics coordination structure on the Moulon plateau in Orsay (IdF). It brings together around 100 researchers and teacher-researchers, experimentalists and theorists, and its research activity is supported by around 60 engineers, technicians, and administrative staff. Each year, the laboratory welcomes a large number of undergraduate and graduate students, including many doctoral students, as well as postdoctoral researchers and visiting scientists. The laboratory covers a wider range of topics than its name suggests, and aims to address the full diversity of condensed matter physics. Research activity is organized around three main areas, each involving roughly the same number of scientists:
• New electronic states of matter
• Physical phenomena in reduced dimensions
• Soft matter and the physics-biology interface
The first area covers both experimental and theoretical studies relating to the properties of systems in which electronic correlations are generally strong and which exhibit remarkable properties and unconventional electronic states such as superconductivity, magnetism, metal-insulator transitions, etc. The second area covers activities relating to “nanoscience” in the broadest sense. These are approached here from the perspective of fundamental properties, when the dimensions of an object become as small as certain characteristic distances (coherence length, mean free path, etc.). The third area extends the concept of “soft matter” to biological systems. The themes therefore range from complex systems to living tissues, from liquid crystals to foams, including polymers and granular systems. These physical studies are at the interface with physical chemistry and biology. The research will be carried out within the MATRIX team at the Laboratoire de Physique des Solides (CNRS-UMR 8502). This research project is funded by the ANR.

Compensation and benefits

Compensation

Starting at €3,131.32 gross monthly salary depending on experience

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

The research professions