The aim of this proposal is to study the structure of alkaline-earth aluminates MO-Al2O3 (M= Sr and Ba) in both the glassy and liquid states. This study will extend the previous work performed at the ILL on the CaO-Al2O3 system. In particular, it will be possible to study the structural evolution as a function of the size of the alkaline-earth cation.Structural information derived from the pair-distribution functions (distances, coordination numbers) will be useful for understanding the mechanism of glass formation in these systems.For this experiment, we will use the levitation setup developed by the CEMHTI (Orleans) and integrated into the D4c diffractometer.These experiments will be complemented by X-ray diffraction and absorption (EXAFS) measurements, and Molecular Dynamics simulations will also be performed in collaboration with the ILL's computing group (C-lab).