Hydrogen diffusion and electronic structure parameters in tantalum hydrides determined by pulsed NMR measurements. [77/sup 0/K-470/sup 0/K]

Conference · Mon Jan 01 04:00:00 EST 1979

OSTI ID:6489294

Hornung, P A; Khan, A D; Torgeson, D R; Barnes, R G

Measurements are reported of the proton spin-lattice relaxation time T/sub 1/ in the tantalun--hydrogen system over the temperature and composition ranges, 77/sup 0/K less than or equal to T less than or equal to 470/sup 0/K and 0.155 less than or equal to H/Ta less than or equal to 0.677, respectively. In the high temperature, solid-solution (..cap alpha..) phase, the activation energy for hydrogen diffusion determined from the dipolar contribution to T/sub 1/, shows a weakly increasing trend from 0.134 eV/atom at H/Ta = 0.155 to 0.140 eV/atom at H/Ta = 0.677. Boundaries between ordered hydride phases and the ..cap alpha.. phase, located by the occurrence of abrupt changes in T/sub 1/, agree very well with other recent determinations. The quantity (T/sub 1e/T)/sup -1/2/, based on the conduction electron contribution, (T/sub le/)/sup -1/, to the relaxation rate (T/sub 1/)/sup -1/, is proportional to the density of states at the Fermi level N(E/sub F/). (T/sub 1e/T)/sup -1/2/ decreases linearly with increasing hydrogen concentration, similarly to its behavior in the V--H and Nb--H systems.

• Research Organization: Iowa State Univ. of Science and Technology, Ames (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6489294
• Report Number(s): IS-M-178; CONF-790301-2
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ACTIVATION ENERGY
CRYOGENIC FLUIDS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
DENSITY
DIFFUSION
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY
FLUIDS
HIGH TEMPERATURE
HYDRIDES
HYDROGEN
HYDROGEN COMPOUNDS
LOW TEMPERATURE
MEDIUM TEMPERATURE
METALS
MOESSBAUER EFFECT
NONMETALS
PERMEABILITY
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
REFRACTORY METALS
RELAXATION
TANTALUM
TANTALUM COMPOUNDS
TANTALUM HYDRIDES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS