title: Immobilization of radioactive iodine in silver aluminophosphate glasses.
abstract: Silver aluminophosphate glasses have been investigated as matrices for the immobilization of radioactive iodine. In this study, up to 28mol% AgI have been incorporated without volatilization thanks to a low temperature synthesis protocol. Alumina was added in the composition in order to increase the glass transition temperature for a better thermal stability in a repository conditions. Two series of glasses have been investigated, based on AgPO3 and Ag5P3O10 compositions, and with 0-5mol% Al2O3. We report (31)P, (27)Al and (109)Ag NMR study of these glasses, including advanced measurement of the connectivities through {(27)Al}-(31)P cross-polarization and (31)P-(31)P double-quantum correlation. We confirm that AgI is inserted in the aluminophosphate glasses and does not form clusters. AgI does not induce any modification of the glass polymerization but only an expansion of the network. Despite no evidence for crystallization could be obtained from XRD, NMR revealed that the introduction of AgI induces an exclusion of alumina from the network, leading to the crystallization of aluminophosphate phases such as Al(PO3)3 or AlPO4. As a consequence, despite NMR gives evidence for the presence of aluminophosphate bonds, only a limited effect of alumina addition on thermal properties is observed.
authors.affiliation: CEA, DEN, DTCD/SECM/LDMC - Marcoule, F-30207 Bagnols-sur-Cèze, France; Université Lille Nord de France, UCCS, UMR - CNRS 8181, F-59652 Villeneuve d'Ascq, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lemesle
authors.affiliation: Université Lille Nord de France, UCCS, UMR - CNRS 8181, F-59652 Villeneuve d'Ascq, France. Electronic address: francois.mear@univ-lille1.fr.
authors.forename: François O
authors.initials: FO
authors.lastname: Méar
authors.affiliation: CEA, DEN, DTCD/SECM/LDMC - Marcoule, F-30207 Bagnols-sur-Cèze, France.
authors.forename: Lionel
authors.initials: L
authors.lastname: Campayo
authors.affiliation: CEA, DEN, DTCD/SECM/LDMC - Marcoule, F-30207 Bagnols-sur-Cèze, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Pinet
authors.affiliation: NMR Center of the University Lille 1, F-59652 Villeneuve d'Ascq, France.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Revel
authors.affiliation: Université Lille Nord de France, UCCS, UMR - CNRS 8181, F-59652 Villeneuve d'Ascq, France.
authors.forename: Lionel
authors.initials: L
authors.lastname: Montagne
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D007454:Iodides / Q000737:chemistry; D007457:Iodine Radioisotopes / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry; D011850:Radioactive Waste; D018030:Silver Compounds / Q000737:chemistry; D018505:Waste Management
chemical_list: D007454:Iodides; D007457:Iodine Radioisotopes; D010710:Phosphates; D011850:Radioactive Waste; D018030:Silver Compounds; C030584:silver iodide; D000537:Aluminum Oxide; C039072:silver phosphate
keywords: Aluminophosphate glass; Iodine immobilization; NMR; Silver iodine; Thermal properties