Crystal structure, hydrogen absorption properties and crystal structure of the deuterides of some Nb–Ni derived image phase compounds

Ternary compounds in the Nb–Ni–V system with the structure of the image phase (structure type W6Fe7, image) have been investigated as regards their hydrogenation properties as a function of V content. On the other hand, the crystal structures of the image phase deuterides Nb57Ni43D44 (Nb7.2Ni5.8D5.03, image, a=5.103(1) Å, c=27.649(3) Å, image, RBragg=11.6%), Nb42Ni31V27D64 (Nb5.32Ni4.08V3.6D8.73, image, a=5.136(1) Å, c=27.815(3) Å, Z=3, RBragg=7.5%) and Nb48Ni23Al29D36 (Nb6.27Ni2.93Al3.8D4.37, image, a=5.113(1) Å, c=27.926(3) Å, Z=3, RBragg=7.4%) have been studied by powder neutron diffraction and are discussed in terms of the metal atom distribution in the metallic substructure, the latter being established by means of joint refinement of neutron and X-ray diffraction data.