Nuclear magnetic resonance studies of metal-hydrogen systems

Technical Report · Wed Feb 01 04:00:00 EST 1989

OSTI ID:6493801

Han, J

Pulsed nuclear magnetic resonance methods have been used to investigate the properties of various metal-hydrogen systems including ZrH/sub x/, ScH/sub x/, NbH/sub x/, VH/sub x/ etc. For pure dihydride-phase samples of ZrH/sub x/, the spin-lattice relaxation time T/sub 1/ has been measured as a function of temperature in the temperature range from 10 K to 1300 K at 12.2 MHz and 40 MHz. These measurements show that the activation energy E/sub a/ for hydrogen diffusion first increases smoothly from 0.57 eV/atom at x = 1.58 to 0.63 eV/atom at x = 1.93 and then increases quite rapidly near the stoichiometric limit, reaching 1.06 eV/atom at x = 1.98. T/sub 1/ measurements at temperatures below 300 K reveal that the d-band electronic states are split due to the Jahn-Teller effect. For ZrH/sub x/ samples doped with paramagnetic impurity ions (Mn, Cr, Fe), an additional spin-lattice relaxation rate R/sub 1p/ was observed. The rate R/sub 1p/ increases in the sequence Fe-Cr-Mn and also increases sharply with increasing hydrogen concentration in each case. The former result is consistent with the observation that the tendency towards localized-moment formation in Zr increases in the same sequence, whereas the latter may be accounted for by the anti-trapping behavior of these impurities. For dilute solid ..cap alpha..-phase ScH/sub x/, we measured T/sub 1/ of both /sup 1/H and /sup 45/Sc as a function of temperature to investigate hydrogen diffusion. The activation energy E/sub a/ = 0.54 eV/atom and attempt frequency ..nu../sub 0/= 1 /times/ 10/sup 14/ Hz were obtained. The absence of a prefactor anomaly in this dilute system is consistent with the hypothesis that such anomalies in other systems may result from repulsive particle-particle interactions at the saddle point. 95 figs.

• Research Organization: Ames Lab., IA (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6493801
• Report Number(s): IS-T-1359; ON: DE89007631
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
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Cermets
& Refractories-- Physical Properties
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Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ELECTRONIC STRUCTURE
HYDRIDES
HYDROGEN COMPOUNDS
MAGNETIC RESONANCE
NIOBIUM COMPOUNDS
NIOBIUM HYDRIDES
NUCLEAR MAGNETIC RESONANCE
PHYSICAL PROPERTIES
REFRACTORY METAL COMPOUNDS
RELAXATION
RELAXATION TIME
RESONANCE
SCANDIUM COMPOUNDS
SCANDIUM HYDRIDES
SPIN-LATTICE RELAXATION
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS
VANADIUM HYDRIDES
ZIRCONIUM COMPOUNDS
ZIRCONIUM HYDRIDES