New hydrides of ternary intermetallics based on Zr with Fe, Co, Ni and Sn or Sb

A series of hydrides based on the alloys Zr6M1.5'X-1.5 (M' = Fe, Co, Ni, X = Sn, Sb) and Zr6NiAl2 have been synthesized (conditions of hydrogenation: T = 130 degrees C, P-H2 = 20 MPa) and their crystal structures have been de termined using both X-ray and neutron diffraction. During hydrogenation the crystal structure of Zr6M1.5'Sb-1.5 and Zr6Fe1.5Sn1.5 changes from the Fe2 P type to the Ni3P type (Zr5M'X2Hsimilar to 11). The hydrogen atoms occupy eight sites, six of those have a tetrahedral coordination whereas two H ato ms occupy trigonal bipyramids. The structure of Zr6NiAl2D7.5 (and Zr6NiAl2H 9.6) has a doubled c cell parameter reference to the starting alloy; it bel ongs to the Zr6FeAl2D10 structure type. (C) 1999 Published by Elsevier Scie nce Ltd on behalf of international Association for Hydrogen Energy. All rig hts reserved.