摘要:
Investigations made by powder X-ray diffraction on two new ternary Sm,Co,Si, and Sm,Ni,Si, compounds and their interaction with hydrogen are reported. The compounds Sm,Co,Si, (a=1.1859(5) nm, c=0.4194(1) nm) and Sm,Ni,Si, (n=1.181(2) nm, c=0.4212(3) nm) crystallize in the hexagonal Ce6Ni2Si3-type structure (space group P6(3)/m). The hydride phases of the Sm6Co2Si3 and Sm6Ni2Si3 are not stable. Hydrogenation leads to decomposition of the intermetallic compound with formation of SmH2 hydride (CaF2-type structure). However, the Sm6Ni2Si3Hx hydride phase was detected. Sm6Ni2Si3Hx preserves the structure type of the starting compound (a=1.257(2) nm, c=0.4016(4) nm) with anisotropic unit cell distortion. the lattice parameter, a, and the unit cell volume, V, increased (da/a=0.064, dV/V=0.080), while the parameter, c, decreased (dc/c=-0.047). (C) 2001 Elsevier Science B.V. All rights reserved.