Solid-state NMR investigation of phosphorus in aluminoborosilicate glasses

Simulants of vitrified low-level radioactive waste forms, with the approximate composition yP(2)O(5)-(0.034)SO3- (1.098)B2O3-((8.030))SiO2-AL(2)O(3)-(2.741)Na2O(where 0.071 less than or equal to y less than or equal to 0.581), have been studied by P-31 magic angle spinning (MAS) nuclear magnetic resonance (NMR) to determine the dominant modes of phosphorus incorporation in these materials, both inside and outside the glass network. Several distinct environments have been identified, with some of the nearest neighbor cations of phosphorus sites inferred by manipulating the B-11, Al-27, or Na-23 resonances together with the P-31 resonance in double resonance NMR experiments. Combined with numerical deconvolution of the P-31 MAS NMR spectra, the concentrations of the 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 Published by Elsevier Science B.V.