Hydrogen interaction with IMC RNi (R = Sm, Tb, Gd, Dy)

摘要

The hydrogenation of GdNi, TbNi, DyNi and SmNi at room temperature and hydrogen pressure below 1 atm has been studied. Ternary hydrides GdNiH_(3.2), TbNiH_(3.4), DyNiH_(3.4) and SmNiH_(3.7) crystallize in orthorhombic CrB-type structure (S.G. Cmcm). The hydrides formation is accompanied with the strong lattice expansion. On the basis of neutron diffraction patterns refinement the atomic positions of D atoms and interatomic distances were determined for TbNiD_(3.4) and DyNiD_(3.4) samples. Deuterium atoms occupy three types of interstitial sites in the structure of TbNiD_(3.4) and DyNiD_(3.4): 4(c)-tetrahedron sites [R_3Ni], 8(f)-trigonal bipyramide sites [R_3Ni_2] and linear 4(b)-sites [Ni_2].