SOLID-STATE NMR INVESTIGATION OF PHOSPHORUS IN ALUMINOBOROSILICATE GLASSES

Simulants of vitrified low-level radioactive waste forms, with the app roximate composition yP(2)O(5)-(0.034)SO3- 098)B2O3-((8.030))SiO2-AL(2 )O(3)-(2.741)Na2O(where 0.071 less than or equal to y less than or equ al to 0.581), have been studied by P-31 magic angle spinning (MAS) nuc lear magnetic resonance (NMR) to determine the dominant modes of phosp horus incorporation in these materials, both inside and outside the gl ass network. Several distinct environments have been identified, with some of the nearest neighbor cations of phosphorus sites inferred by m anipulating the B-11, Al-27, or Na-23 resonances together with the P-3 1 resonance in double resonance NMR experiments. Combined with numeric al deconvolution of the P-31 MAS NMR spectra, the concentrations of th e various phosphorus-containing species have been estimated from these results, and the partitioning of phosphorus in the glass is deduced. These experiments and others also reveal the existence and identities of separate ortho- and pyrophosphate phases in the glass. (C) 1998 Pub lished by Elsevier Science B.V.