Double-rotation NMR, magic angle spinning NMR, and x-ray diffraction study of the structure of aluminum molybdate

An 27 Al NMR study of aluminum molybdate (Al 2 (MoO 4 ) 3 ) has been carried out. Using the double-rotation technique (DOR), the residual line broadening observed in magic angle spinning (MAS) that is caused by second-order quadrupolar interactions is completely removed. The four inequivalent aluminum resonances, as predicted from the space group symmetry obtained from X-ray and neutron powder diffraction data, are clearly revealed by NMR. Moreover, additional structure in the DOR spectrum may be indicative of further inequivalency in the unit cell that is not discernible by powder diffraction methods