P-31 MAGIC-ANGLE-SPINNING NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY OF CALCIUM-PHOSPHATE GLASSES

P-31 Magic-angle spinning nuclear magnetic resonance (MAS NMR) spectro scopy of a series of Ca phosphate glasses yields the following results and conclusions: (1) The relative concentrations of Q1, Q2, and Q3 P- tetrahedra are consistent with theoretical expectation and previous ex perimental work, except that near the metaphosphate composition tetrah edra with all three polymerizations are present. This increased range of polymerizations is consistent with previous work on silicate compos itions. (2) The chemical shift of P-31 pin Q2 polymerization becomes l ess shielded (less negative) with increasing Ca content, parallelling the previously published results for Na phosphate glasses. (3) The che mical shifts are systematically more negative than for the Na phosphat e glasses, consistent with theoretical expectation and experimental wo rk.