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Title: X- and neutron diffraction study of UCr/sub 2/O/sub 6/ monocrystal. Determination of crystallographical and magnetic structures (in French)

Journal Article · · J. Solid State Chem.; (United States)

The structure of UCr/sub 2/O/sub 6/, PbSb/sub 2/O/sub 6/ type compound was refined from x-ray and neutron single crystal data. The symmetry is trigonal, space group P31m. The lattice parameters are a = 4.990 (1) A; c = 4.622 (1)A. There is one molecule per unit cell. The uranium, chromium, and oxygen atoms occupy the 1a (0,0,0), 2d(1/3, 2/3, 1/2), 6k(x,0,z) positions, respectively, with x = 0.3405 (3) and z = 0.2647 (2). The final R factors are 0.033 for the x-ray data and 0.0294 for the neutron data. The anisotropic temperature factors have been introduced in last stage of both refinements. The average cation-anion interatomic distances are U--O = 2.094 (1) A, Cr--O = 1.9726 (8) A. From these values it can be deduced that the uranium and chromium are hexavalent and trivalent respectively. From powder diffraction diagrams at 298 and 4.2/sup 0/K, it has been determined that the spin of the Cr/sup 3 +/ are located in the basal plane with an antiferromagnetic type arrangement. The value of the magnetic moment is 2.6 ..mu..B. (auth)

OSTI ID:
7365377
Journal Information:
J. Solid State Chem.; (United States), Vol. 16:1-2
Country of Publication:
United States
Language:
French