NMR study of fluoride ion diffusion in potassium-doped β-PbF_2

Citation

Cannon, David M. (1978) NMR study of fluoride ion diffusion in potassium-doped β-PbF_2. Master's thesis, California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:03292010-111321744

Abstract

Fluoride ion motion in a KF-doped β-PbF_2 crystal was studied by measuring the ^(19)F relaxation times T_1, T_2, and T_(1p). Measurements were made on a 56.4 MHz pulsed spectrometer over the temperature range -101°C to 22°C; the T_(1p) data were taken in a rotating magnetic field of 6.8 G. Two sets of T_2 data were taken, yielding activation energies of 0.17 ± 0.01 eV and 0.18 ± 0.01 eV. Activation energies obtained from T_1 and T_(1p) data were 0.17 ± 0.01 eV and 0.34 ± 0.02 eV, and a correlation time of 2.9 µsec was observed at -20°C, the temperature at which the T_(1p) minimum occurs. Comparison of these data with previously published results shows that potassium-doping is more effective than sodium-doping in activating fluorine motion. It is believed that T_1 relaxation is dominated by a mechanism other than anionic diffusion.

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