NMR Study of Fluoride Ion Diffusion in Potassium-Doped β-PbF₂

Author: Cannon, David Maxwell

Year: 1978

Degree: Master's thesis

Advisor: Vaughan, Robert W.

Committee Member: Unknown, Unknown

Option: Chemistry

DOI: 10.7907/8dgg-dx50

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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