Powder neutron diffraction studies of Y/sub 6/Mn/sub 23/D/sub 23/, Er/sub 6/Mn/sub 23/D/sub 23/, and LaNi/sub 4/ /sub 5/Al/sub 0/ /sub 5/D/sub 4/ /sub 5/

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6108590

Crowder, C E

Powder neutron diffraction techniques are used to determine the crystallographic structures of Y/sub 6/Mn/sub 23/D/sub 23/, Er/sub 6/Mn/sub 23/D/sub 23/, and LaNi/sub 4/ /sub 5/Al/sub 0/ /sub 5/D/sub 4/ /sub 5/. It has been found that while Y/sub 6/Mn/sub 23/ and Er/sub 6/Mn/sub 23/ have face-centered cubic structures, their deuterides are body-centered tetragonal. Deuterium atoms are found in the (2a), (16n), (16m), (16/), and (32o) crystallographic sites (14/mmm symmetry, Wycoff notation) for both compounds. The metal atoms are still very close to their original cubic positions. For LaNi/sub 4/ /sub 5/Al/sub 0/ /sub 5/D/sub 4/ /sub 5/, a proposed structure with P6/mmm symmetry agrees significantly better with experimental neutron diffraction data than does a structure having P31m symmetry. The P6/mmm structure contains two deuterium sites, namely the (6m) and (6i). A configurational entropy calculated for this structure is in good agreement with an experimentally derived value. The locations of the deuterium atoms give evidence of their high mobility. Neutron diffraction results at reduced temperatures coupled with magnetic susceptibility measurements have allowed determinations of the magnetic structures of Y/sub 6/Mn/sub 23/D/sub 23/ and Er/sub 6/Mn/sub 23/D/sub 23/. Originally thought to be Pauli paramagnets, the evidence clearly indicates that these two deuterides are actually antiferromagnetic.

• Research Organization: Missouri Univ., Rolla (USA)
• OSTI ID: 6108590
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ALLOYS
ALUMINIUM ADDITIONS
ALUMINIUM ALLOYS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DEUTERIDES
DEUTERIUM COMPOUNDS
DIFFRACTION
ERBIUM ALLOYS
HYDROGEN COMPOUNDS
LANTHANUM ALLOYS
MAGNETIC PROPERTIES
MANGANESE ALLOYS
NEUTRON DIFFRACTION
NICKEL ALLOYS
PHYSICAL PROPERTIES
RARE EARTH ALLOYS
SCATTERING
YTTRIUM ALLOYS