Incorporation of P2O5 in a Na2O-rich aluminoborosilicate glass

• Published in: Materials letters 2024-12, Vol.377, p.137283, Article 137283
• Main Authors: Achigar, Sophie, Caurant, Daniel, Régnier, Elise, Majérus, Odile, Charpentier, Thibault
• Format: Article
• Language: English
• Subjects: 29Si MAS NMR; Borosilicate glass; P2O5 solubility; Phosphate crystallization
• ISSN: 0167-577X
• DOI: 10.1016/j.matlet.2024.137283

•A Na-rich borosilicate glass is considered to immobilize dismantling nuclear waste rich in phosphorus.•The incorporation of P2O5 (0–10 mol%) present in waste is studied by XRD and SEM.•P2O5 addition can lead to the crystallization of Na3PO4, NaCaPO4 (from 2 mol%) and Na4P2O7 (from 10 mol%)•Crystallization leads to the depletion of Na2O and CaO in the residual glass increasing its polymerization. This work focuses on the effect of adding increasing amounts of P2O5 (0–10 mol%) on the microstructure and crystallization tendency of a Na2O-rich aluminoborosilicate simplified nuclear glassy matrix obtained after melt quenching or controlled cooling from 1100 °C. Above 2 mol% P2O5, phase separation followed by crystallization of Na3PO4 occurred, then followed by NaCaPO4 and even Na4P2O7 when P2O5 content reached 10 mol%. The Na2O and CaO depletion induced in the residual glass by phosphate phases crystallization is responsible for an important increase of its glass transition temperature due to a significant increase of the silicate network polymerization as confirmed by 29Si MAS NMR.