NUCLEAR MAGNETIC RELAXATION IN LiF AT HIGH TEMPERATURES

Journal Article · Tue Oct 15 00:00:00 EDT 1963 · Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D

DOI:https://doi.org/10.1103/PhysRev.132.630· OSTI ID:4645111

Eisenstadt, M

Measurements of T/sub 1/ and T/sub 2/, the spin-lattice and spinspin relaxation times, are reported for Li/sup 7/ and Fi/sup 9/ nuclei in a single crystal of LiF. Ti(Li) was measured from room temperature to the melting point (1120 deg K) and the other quantities from 830 deg K to the melting point. Above 620 deg K, relaxation is caused exclusively by the diffusion of Li and F ions. T/ sub 1/(Li), T/sub 2/(Li), and T/sub 1/(F) are mainly determined by nu /sub Li/, the jump frequency of Li ions, and T/sub 2/(F) mainly by nu F. Using a theory of relaxation developed elsewhere, nu /sub Li/ and nu /sub F/ are obtained for the region of intrinsic diffusion as nu /sub Li/ = 1.7 x 10/sup 16/ exp (-1.81 eV/ kT) and nu /sub F/ = 4.5 x 10/sup 17/ exp (-2.2 ev/kT). For the extrinsic region, the motional activation energy of Li ions is obtained as 0.71 ev. The values of nu /sub Li/ are in good agreement with those obtained from conductivity measurements. Below 620 deg K quadrupolar relaxation due to lattice vibrations and relaxition by paramagnetic impurities become important, and rough values are obtained for these contributions to T/sub 1/(Li), Large angular variations of T/sub 1/ and T/sub 2/ are observed in the region of relaxation due to atomic diffusion. T/sub 2/(Li) and T/sub 1/(Li) vary by a factor of 2 and 1.5, respectively, as a function of crystal orientation, in good agreement with theoretical prediction. A crude measurement of T/sub 1/(Li) in molten LiF is discussed. (auth)

• Research Organization: Columbia Univ., New York
• NSA Number: NSA-17-039067
• OSTI ID: 4645111
• Journal Information: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D, Journal Name: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D Vol. Vol: 132; ISSN PHRVA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ACTIVATION ENERGY
ATOMS
CHEMISTRY
DEFORMATION
DIFFUSION
ELECTRIC CONDUCTIVITY
ELECTRIC FIELDS
ENERGY
EQUATIONS
EXCITATION
FLUORINE 19
FLUORINE COMPOUNDS
FREQUENCY
FUSED SALTS
HIGH TEMPERATURE
IMPURITIES
IONS
LATTICES
LITHIUM 7
LITHIUM COMPOUNDS
LITHIUM FLUORIDES
MAGNETIC MATERIALS
MAGNETISM
MEASURED VALUES
MELTING POINTS
MONOCRYSTALS
MOTION
NUCLEAR MAGNETIC RESONANCE
NUCLEAR MODELS
OSCILLATIONS
PARAMAGNETISM
QUADRUPOLES
QUANTITATIVE ANALYSIS
RELAXATION
SPIN
SPIN-LATTICE RELAXATION
TEMPERATURE
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