“…9,10 During high-temperature treatment, the viscosity of these systems plays a fundamental role in controlling several phenomena, such as melting, bath-to-glass conversion, particle aggregation, mass transfer, bubble removal, and the quality of the final product. [11][12][13][14][15][16][17][18][19] Glass-ceramic matrices are an alternative way to immobilize nuclear waste because higher amounts of HLWs can be vitrified and these matrices could offer a higher flexibility in the management of various waste streams. In such processes, different physicochemical transformations, such as bubble formation, liquid-liquid phase separation, and/or crystallization may take place.…”