Solid-state NMR study of inorganic fluorides and oxyfluorides

The research presented in this dissertation involves the uses of magnetization transfer, double resonance NMR and MQMAS techniques to investigate the fluorine/oxygen ordering and the motional dynamics in fluorides and oxyfluorides.; A series of oxyfluorides were synthesized and characterized using 19F high speed MAS NMR in order to probe the ordering/disordering in oxyfluorides. Two-dimensional magnetization transfer (such as CP, HETCOR and spin diffusion) and double resonance techniques (such as REDOR) were applied in order to explore site proximity. In most cases, the results of O/F ordering are consistent with the previous studies proposed by Bond-Length Bond-Strength calculation and/or Raman spectroscopy. In some cases however, fluorine is disordered in the anion sites and the degree of disorder is not related to the synthesis method.; The phase transition and mobility of Na3WO3F 3 were studied with variable temperature 19F and 23Na MAS NMR. The 19F → 23Na HETCOR and 23Na MQMAS techniques have been successfully applied to the cryolite oxyfluoride (Na3WO3F3) at different temperatures. Oscillatory rotation along the c axis in the alpha phase and free rotation of W octahedra in the beta phase were proposed in this study.; A high-order spin diffusion mechanism, where four spins undergo spin diffusion at the same time in order to compensate for the significant energy mismatch, was proposed to explain the unusual negative cross-peaks and unique polarization transfer dynamics in 19F 2-D magnetization-exchange experiment of Ba2MoO3F4.; A variety of NMR interactions were characterized in K2NbF 7, Cdpy4NbOF5 and [pyH]2[CdPY 4(NbOF5)2] (py = C5H5N), such as the chemical shielding anisotropy, direct dipolar coupling, J-coupling and the quadrupolar interaction. Isotropic J-coupling between 93Nb and 19F has been observed for the first time in solid-state 19F MAS spectra. A very large 93Nb Chemical shielding anisotropy (&OHgr; = 1000 ppm) in 93Nb spectra was also observed for the first time. The intramolecular dynamics of K2NbF7 was studied by variable temperature 93Nb static and 19F MAS NMR experiments. The disorder mechanism in Cdpy4NbOF5 adopts interchain cancellation of O/F ordering. A methodology of simulation for the system with large chemical shielding and quadrupolar interactions was proposed.