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What is the mechanism of hydrogen absorption in rare-earth intermetallics

Journal Article · · J. Appl. Phys.; (United States)
DOI:https://doi.org/10.1063/1.323551· OSTI ID:5365250
We have studied the intermetallic compounds EuPd and EuRh/sub 2/, and the corresponding saturated hydrides, via Eu Moessbauer spectroscopy, magnetic measurements, and x-ray diffraction. In both intermetallics, the Moessbauer parameters, indicative of the environment about the Eu ion, change substantially in the hydriding process and approach those of EuH/sub 2/. We interpret those changes as evidence that the hydrogen absorption occurs via the formation of EuH/sub 2/ ''complexes''. For the EuRh/sub 2/, a simple thermodynamic argument supports this approach. The EuRh/sub 2/ maintains the same crystal structure under H/sub 2/ absorption, but the Eu/sup 3 +/ becomes Eu/sup 2 +/, and the lattice volume increases by 40%. EuPd changes structure under H/sub 2/ absorption, but the Eu remains divalent. Results of magnetic and crystallographic measurements are presented. With partial hydriding, only the pure intermetallic and saturated hydride phases are observed to occur.
Research Organization:
Bell Laboratories, Murray Hill, New Jersey 07974
OSTI ID:
5365250
Journal Information:
J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 48:12; ISSN JAPIA
Country of Publication:
United States
Language:
English