Low pressure glass-ceramics for the immobilization of long-lived iodine radioisotopes

There have been substantial scientific works in the past years for finding adequate immobilization matrices for iodine radioisotopes. Lately, iodosodalite glass-ceramics or glasscomposites represent a promising material. Under pressure, glass-ceramics represent an even better material. In the present work, we have synthesised I-bearing glass-ceramics under low pressure conditions (0.5 GPa) and using a thermal step from melting (1250°C) to crystallization temperature (813°C). The produced materials show the coexistence between Irich iodosodalite (>10 mol.% I) and I-poor glass matrix (<1 mol.% I) and without the presence of detrimental crystalline phase such as nepheline. The iodosodalite proportion remains low though (~10%). Raman spectroscopy on the iodosodalite crystals seems to indicate that the β cage could be filled either with I$^-$ or IO₃$^-$ species. The analyses of the glass structure using ¹¹B NMR show an increase in the BO₄ proportion that could suggest an increase in the chemical durability. In the end, the produced materials have most of the prerequisite for a relevant matrix for immobilization of iodine radioisotopes.