Moessbauer effect investigations of the electronic and magnetic properties of rare earth metal and intermetallic hydrides

Journal Article · Thu Nov 01 04:00:00 EST 1979 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.326837· OSTI ID:5740841

Dunlap, B D; Shenoy, G K; Friedt, J M; Viccaro, P J; Niarchos, D; Kierstead, H; Aldred, A T; Westlake, D G

Moessbauer spectroscopy has been used in a number of investigations of elemental rare earth (RE) metal and RE--transition metal intermetallic hydrides. Analysis of hyperfine parameters has established the crystalline electric field (CEF) ground state for Dy/sup 3 +/ in DyH/sub 2/ and for Er/sup 3 +/ in ErH/sub 2/ and YH/sub 2/. In all cases the results are compatible with the presence of negatively charged hydrogen atoms. Long range magnetic ordering is observed in the RE-H/sub 2/ compounds. In DyH/sub 2/, short-range magnetic ordering is seen at temperatures up to twice the long-range transition temperature. This arises from the changes in CEF symmetry due to the presence of a few H atoms which are not in regular tetrahedral sites. These effects are much more pronounced in slightly non-stoichiometric compounds and can result in dramatic changes in the magnetic ordering temperature. As an example of an intermetallic hydride, we have studied the cubic Laves phase RE-iron compounds. These form several stable hydride phases RE-Fe/sub 2/H/sub x/, with the maximum x being in excess of 4. The magnetic transition temperatures decrease to roughly half their original values for x=3.5, and the RE-Fe exchange interaction is weakened. For x=4, a sharp reduction in both the Fe magnetic moment and the magnetic ordering temperature occurs.

• Research Organization: Argonne National Laboratory, Argonne, Illinois 60439
• OSTI ID: 5740841
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 50:B11; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ALLOYS
CRYSTAL FIELD
ELECTRONIC STRUCTURE
HYDRIDES
HYDROGEN COMPOUNDS
HYPERFINE STRUCTURE
INTERMETALLIC COMPOUNDS
IRON COMPOUNDS
LAVES PHASES
MAGNETIC MOMENTS
MAGNETIC PROPERTIES
MOESSBAUER EFFECT
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE