Neutron diffraction studies of Zr-containing intermetallic hydrides with ordered hydrogen sublattice. V. Orthorhombic Zr3CoD6.9 with filled Re3B-type structure

Zr3CoD6.9 deuteride (space group Cmcm; a=3.5959(1); b=10.9734(3); c=9.5961(3) A) has been studied by high resolution powder X-ray and neutron diffraction. Rietveld profile refinements showed that it is isostructural to Zr3FeD6.7 with a filled Re3B-type structure. D atoms occupy four types of interstitial positions. Deuterium sublattice is completely ordered and can be described as a spatial stacking of deformed cubes ZrD8 and deformed cubes with an extra ninth vertex ZrD9. The shortest interatomic distances are: Zr–D=2.044(5); Co–D=1.727(8); D–D=2.025(6) A.