Hydrogen ordering and H-induced phase transformations in Zr-based intermetallic hydrides

Crystal chemistry aspects of hydrogen behaviour in the zirconium–iron intermetallic deuterides (hydrides), Zr2FeD1.80–5.00, Zr3FeD1.27–6.70 and Zr4Fe2O0.6H7.80, were studied with a focus on the application of high resolution powder neutron diffraction. The effects of crystal structure, chemical composition of the metal matrices, temperature and hydrogen contents on preferences in the interstices occupation and H ordering were investigated and discussed in relation to the H absorption–desorption properties. The Hydrogenation–Disproportionation–Desorption–Recombination process was successfully applied to all materials studied, including the first reported example of an oxygen-containing compound, Zr4Fe2O0.6.