Voies de nucléation classiques et non-classiques du sulfate de strontium : étude en milieux confinés et non-confinés
Auteur / Autrice : | Andrew Robert Lauer |
Direction : | Roland Hellmann, Alejandro Fernandez-martinez, Alexander Van driessche |
Type : | Projet de thèse |
Discipline(s) : | Sciences de la Terre et de lEnvironnement |
Date : | Inscription en doctorat le Soutenance le 19/03/2024 |
Etablissement(s) : | Université Grenoble Alpes |
Ecole(s) doctorale(s) : | École doctorale Sciences de la Terre de lEnvironnement et des Planètes |
Partenaire(s) de recherche : | Laboratoire : Institut des Sciences de la Terre |
Jury : | Président / Présidente : Laurent Truche |
Examinateurs / Examinatrices : Roland Hellmann, Diane Rebiscoul, Tomasz Stawski, Stephane Veesler | |
Rapporteurs / Rapporteuses : Diane Rebiscoul, Stephane Veesler |
Mots clés
Mots clés libres
Résumé
Classically, solid nucleation is considered to be a stochastic process in which clusters of monomers randomly come together into solid a solid nucleus due to agitation or Brownian motion within a supercritical fluid. However, modern observations shed new light on alternative pathways via which nucleation reactions can occur, specifically via multi-step mechanisms with nano-scale intermediate species. Here, we explore the nucleation of strontium sulfate from aqueous solution within the framework of various nucleation theories. First, we propose the presence of an intermediate participating in the nucleation of celestine, and the concentration-dependent appearance of this non-classical nucleation pathway is discussed in terms of mesoscale nucleation theory. We also examine strontium sulfate hemihydrate, a relatively little-known transient phase that precedes the thermodynamically stable celestine under certain conditions. In situ Raman and XRD reveal that this phase is an independent mineral phase that, when present, dissolves before the nucleation of the stable celestine. The differences in the observed nucleation pathway of this hydrated phase and that of celestine reveals a possible mechanism for phase and polymorph selection during nucleation reactions. Finally, the influence of nanoconfinement on nucleation reactions in the Sr-SO4-H2O system is explored, providing further evidence for the existence of a nucleation intermediate and demonstrating the potential of counterdiffusion in porous media as a method to explore the fundamental nature of nucleation itself.