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

Thesis/Dissertation · Wed Jan 01 00:00:00 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
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

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