NMR study of hydrogen diffusion in metal hydrides containing paramagnetic impurities

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6215874

Phua, T T

The pulsed NMR of hydrogen nuclei in LaH/sub x/ and YH/sub x/ with and without paramagnetic impurities (Ce, Nd, Gd, Dy, Er) was studied. Measurements of proton T/sub 1/ were carried out in the temperature range from 77K to 800K at a resonance frequency of 400MHz. The data for both pure LaH/sub x/ show unambiguously that the hydrogen diffusion rate increases with increasing hydrogen content. It is concluded that increased occupancy of the octahedral sublattice causes the potential wells at octahedral and tetrahedral sites to become shallower and lowers the energy barrier to motion between the two sublattices. For systems with controlled dilute paramagnetic impurities, an additional spin-lattice relaxation process was found and appears to be essentially due to the dipolar coupling between impurity and proton moments. The study showed that the impurity induced relaxation rate is very sensitive to the magnetic moment and relaxation rate of the impurity ion, as well as depending on the host hydride composition. Serious errors in deduced diffusion and electronic structure parameters may be made unless effects of impurities are recognized and allowed for.

• OSTI ID: 6215874
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
CERIUM
DIFFUSION
DYSPROSIUM
ELEMENTS
ERBIUM
GADOLINIUM
HYDRIDES
HYDROGEN
HYDROGEN COMPOUNDS
IMPURITIES
LANTHANUM COMPOUNDS
LANTHANUM HYDRIDES
MAGNETIC RESONANCE
METALS
NEODYMIUM
NONMETALS
NUCLEAR MAGNETIC RESONANCE
PERMEABILITY
RARE EARTH COMPOUNDS
RARE EARTHS
RESONANCE
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM HYDRIDES