YCu3Al2, an example of an AB(5) structure type

Yttrium tricopper dialuminium, YCu3Al2, is isostructural with hexagonal CaC u5, in which each Cu atom at the 3g(1/2,0,1/2) position in space group P6/m mm (No. 191) is partially replaced by an Al atom. The hydrogen-uptake prope rties are usually enhanced in other AB(5) structures by aluminium substitut ion. YCu5 does not show any hydrogen absorption, and the goal of the presen t work is to investigate whether aluminium substitution could expand the me tal-atom lattice enough to provide better interstitial positions for hydrog en storage. However, no enthalpy change was observed up to 773 K under 3 MP a static H-2 pressure by differential thermal analysis (DTA) for the title compound. The compound does not show any significant hydrogen absorption/de sorption in the pressure-composition isotherms (P-C-T diagrams) in the temp erature range 298-673 K under 3.3 MPa H-2 pressure.