Nuclear magnetic resonance study of vacancy and interstitial motion in scandium hydrides and deuterides

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:6810545

Jerosch-Herold, M

Nuclear Magnetic Resonance (NMR) methods were used to study the nonstochiometric dihydrides and dideuterides of high purity scandium. For the first time, measurements were made of the spin relaxation time T/sub 1/ and T/sub 2/ of all three nuclear species present (/sup 45/Sc, /sup 2/D, /sup 1/H) in a metal hydride (deuteride) system, permitting a comparison of the main features of both atomic and vacancy motion on the hydrogen sublattice. In the regions of the conventional diffusion induced /sup 45/Sc- and /sup 2/D-T/sub 1/ minima (<800K), the relaxation rates are dominated by fluctuations of the quadrupolar interaction reflecting vacancy motion. The symmetric /sup 1/H-T/sub 1/ minimum can be well described by a Lorentzian (Debye) spectral density function. In contrast, the /sup 45/Sc-T/sub 1/ minimum shows for 1n(Sc-T/sub 1/) versus reciprocal temperature a substantially smaller slope on the high temperature side at high vacancy concentrations. (/sup 45/Sc-T/sub 1/)/sub min/ saturates rapidly for vacancy concentrations larger than c/sub v/ > 0.03 and shows a weaker frequency dependence than expected. The jump-attempt frequencies nu/sub 0/ obtained from the /sup 45/Sc-T/sub 1/ data agree well with the values obtained from neutron scattering measurements, whereas the /sup 1/H-T/sub 1/ data yield anomalously low jump frequency prefactors. Departure of the /sup 45/Sc results from the Lorentzian model are interpreted as indicating the formation of vacancy pairs and the importance of particle-particle interactions.

• Research Organization: Iowa State Univ. of Science and Technology, Ames (USA)
• OSTI ID: 6810545
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
&amp; Refractories-- Structure &amp; Phase Studies
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DEUTERIDES
DEUTERIUM COMPOUNDS
HIGH TEMPERATURE
HYDRIDES
HYDROGEN COMPOUNDS
INTERSTITIALS
MAGNETIC RESONANCE
MOTION
NUCLEAR MAGNETIC RESONANCE
POINT DEFECTS
RELAXATION
RELAXATION TIME
RESONANCE
SCANDIUM COMPOUNDS
SCANDIUM HYDRIDES
SPIN-LATTICE RELAXATION
TRANSITION ELEMENT COMPOUNDS
VACANCIES