Exploration of MₓOy-Al₂O₃-SiO₂ systems through their dynamics and their structure, from the melted medium to the low temperature

Materials science is currently experiencing major advances linked in particular to the originality and increased diversity of synthesis methods, to the maturity of numerical simulation methods associated with the availability of increasingly efficient means of calculation, but also and especially thanks to improvements in characterization techniques, particularly in terms of speed and resolution. This convergence of numerical methods and experimental techniques opens the way to a more systematic study of phase diagrams and to the exploration of the behavior of systems outside of thermodynamic equilibrium. The possibility of controlling the environment of the molten media and the cooling rates are major assets for understanding these systems and the possibility of developing new structures by controlling their thermal history. In this thesis, we will focus on MₓOy-Al₂O₃-SiO₂ oxide diagrams (with MₓOy = ZrO₂, ZnO, SrO, etc.) with a high melting point, the analysis of which requires the production of very high temperatures which cannot be reached by conventional devices. The study of these systems is of great interest in various fields such as the production of alkali-resistant glasses, the design of chemically stable refractories or even the development of glass-ceramics.The development of a new test platform at the CEMHTI laboratory allowing the confinement of molten media by container-free techniques and characterizing both their thermophysical properties and microscopic quantities integrating information on dynamics and structure, provides a natural setting for this study. Exploration of the liquid phase and the supercooling zone should make it possible to identify the conditions conducive to the formation of original phases,whether they are amorphous or crystalline, as well as to better understand the microscopic mechanisms, which are the catalysts for their stabilization. The selected compositions constitute the systems of choice to shed light on this problem. Indeed, the aluminosilicate network is very versatile, it favors the emergence of often-remarkable properties and its interaction with modifier or intermediate elements must make it possible to understand the variability of behaviors and structures.