Accession Number : ADA140757

Title :   Neutron Diffraction Studies of Some Rare Earth-Transition Metal Deuterides.

Descriptive Note : Final rept. 15 Mar 80-15 Nov 83,


Personal Author(s) : James,W J

PDF Url : ADA140757

Report Date : Apr 1984

Pagination or Media Count : 53

Abstract : Neutron diffraction studies of the ternary alloy system Y6(Fel-xMnx)23 reveal that the unusual magnetic behavior upon substitution of Mn or Fe into the end members, is a consequence of atomic ordering wherein there is strong site preference of Mn for the f sub 2 sites and of Fe for the f sub 1 sites. In the Mn-rich compositions, Fe is found to have no spontaneous moments. Therefore, the long range magnetic ordering arises solely from Mn-Mn interactions. Upon substitution of Mn into the Fe-rich ternaries, the Fe moments are considerably reduced. Neutron diffraction studies of Y6Mn23D23 show that a transition occurs below 180K from a fcc structure to a primitive tetragonal structure, space group P4/mmm with the onset of antiferromagnetic ordering. The Mn moments are directed along the c-axis. The transition probably results from atomic ordering of the D atoms at low temperature which induces c axis magnetic ordering. The question of the appropriate space group of LaNi4.5Al0.5D4.5, P6/mmm or P3/m has been resolved by a careful refinement and analysis of neutron diffraction data. The preferred space group is P6/mmm. Neutron powder diffraction and thermal magnetization measurements on small single crystals of ErNi3, ErCo3, and ErFe3 (space group R3m) show that the magnetocrystalline properties are a consequence of competing local site anisotropies between the two non-equivalent crystallographic sites of Er and two of the three non-equivalent sites of the 3d-transition metal.

Descriptors :   *Neutron diffraction, *Diffraction analysis, *Deuterium, *Rare earth compounds, *Transition metal compounds, Ternary compounds, Yttrium alloys, Iron, Manganese, Magnetic properties, Substitution reactions, Atomic structure, Interactions, Lanthanum compounds, Nickel, Aluminum, Hydrides, Erbium compounds, Cobalt, Single crystals, Thermal analysis, Magnetic moments, Crystal structure

Subject Categories : Inorganic Chemistry
      Metallurgy and Metallography
      Test Facilities, Equipment and Methods
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE