Vitrification of Molten Chloride Salts

Abstract Vitrification of molten chloride salts offers a novel approach for preserving their liquid-phase structure as amorphous solids, enabling analysis of liquid structure at room temperature. However, vitrifying molten salts composed of simple salts (e.g., NaCl, KCl) has remained a significant technical challenge due to their strong tendency to crystallize. In this study, a nebulizer was used to successfully vitrify a KCl–MgCl2 mixture for the first time. Powder X-ray diffraction (pXRD) analysis confirmed a substantial reduction in crystallinity, indicating enhanced amorphization of the quenched salts. Four-dimensional scanning transmission electron microscopy (4D-STEM) revealed retention of the amorphous state. Raman spectroscopy confirmed the persistence of tetrahedral [MgCl4]2– motifs in the room-temperature solids, demonstrating preservation of molten-state structural features in the vitrified phase. This work represents a critical advancement in molten salt vitrification, providing a new pathway for structural studies and informing future applications in molten salt reactors and high-temperature chemical processes.