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Neutron diffraction studies of ytterbium dihydride: the crystal structure at 300 K

1983; Wiley; Volume: 39; Issue: 11 Linguagem: Inglês

10.1107/s010827018300894x

1600-5759

B. Lebech, N. Andersen, S. Steenstrup, Allan Schrøder Pedersen,

Thermodynamic and Structural Properties of Metals and Alloys

The crystal structures of YbD 2 and YbH 2 have been studied by elastic neutron scattering on powdered samples at room temperature and atmospheric pressure. The neutron diffraction data have been analysed by means of the EDINP profile structure refinement program. The analyses confirmed the assumption that both compounds are isostructural with the hydrides of the alkaline-earth metals at room temperature and atmospheric pressure. All atoms are found to occupy the 4(c) position in the orthorhombic space group D~ 6 (Prima). The atomic positions were found to be: x(Yb)=0.243, z(Yb)=0.111; x(D') = 0.358, z(D') = 0-433; and'x(D) = -0.021, z(D) = 0.675. By inference from these atomic positions, it is suggested that the room-temperature high-pressure (p > 15 GPa) hexagonal structure of YbH 2 is D4h (P63/mmc) with the metal atoms in 2(c) positions and the hydrogen atoms in 2(a) and 2(d) positions.