A room temperature 17O nuclear magnetic resonance study was made of La2Mo2O9; a fast oxide ionic conductor which exhibited a phase transition, at 580C, between a low-temperature α-phase and a high-temperature β-phase. Four partially overlapping quasi-continuous distributions of O sites were revealed by 1D magic-angle spinning (MAS) and 2D triple quantum MAS NMR experiments. These could be correlated with the 3 oxygen sites O1, O2 and O3 of the high-temperature crystal structure. The low-temperature phase

was characterized by 2 distributed sites of type O1, which proved that the symmetry was lower than that of the cubic high-temperature phase. Two-dimensional experiments showed that there was no dynamic exchange process, on the nuclear magnetic resonance time-scale, between the various O sites at room temperature. This agreed well with conductivity results.

17O NMR in Room Temperature Phase of La2Mo2O9 Fast Oxide Ionic Conductor. J.Emery, D.Massiot, P.Lacorre, Y.Laligant, K.Conder: Magnetic Resonance in Chemistry, 2005, 43[5], 366-71