XRD and solid-state NMR study of magnesium oxide magnesium orthophosphate systems

Various magnesium oxide-magnesium orthophosphate systems in different Mg/P ratios were synthesized and examined by XRD and H-1 and P-31 MAS NMR. The results thus obtained are compared with those for commercially available pure MgO and Mg-3(PO4)(2). The crystallization temperature of magnesium orthophosphate was found to increase with increasing MgO content in the sample, The NMR technique revealed the absence of interactions between the two species, P-31 MAS NMR allowed the amorphous-to-crystalline ratio for magnesium orthophosphate in solids calcined at different temperatures to be determined. Also, H-1 MAS NMR revealed the qualitative nature of hydroxyl sites in the solids. (C) 1998 Academic Press.