Oxygen speciation in nanophase MgO from solid-state O-17 NMR

Nanocrystalline MgO has been sol-gel manufactured to give a range of crystallite sizes from 1.8 to 35 nm as determined by powder X-ray diffraction. A multinuclear magnetic resonance approach using C-13, O-17, and Mg-25 provides information on the atonic scale structure. It is found that despite extensive hydrolysis that -CH3 fragments persist until extensive calcination has been performed. In O-17 magic angle spinning NMR spectra three signals are detected that are assigned to MgO-like, a surface species, and a unit also like MgO but with carbon as the third nearest neighbor, demonstrating the high sensitivity of the O-17 chemical shift to local structure and its ability to detect medium-range order.