23Na NMR studies of doped nasicon systems

The positions of sodium ions in two doped nasicon systems were investigated by using 23Na solid state NMR techniques. The 23Na NMR spectra with a characteristic powder pattern of quadrupole interaction in the Na1−XZr2−XNbXP3O12 system indicated that sodium ions occupy Na(1) sites in the crystal structure. For the Na1 + 2XZr2−XMgXP3O12 system, excepting the compound with X = 0.1, Gaussian lineshapes were observed due to the distribution of quadrupole parameters and the occupation of both Na(1) and Na(2) sites in the crystal structure. Two sodium sites can be distinguished by applying an inversion-recovery experiment.