YCu3Al2, an example of anAB5structure type

Yttrium tricopper dialuminium, YCu(3)Al(2), is isostructural with hexagonal CaCu(5), in which each Cu atom at the 3g((1/2),0,(1/2)) position in space group P6/mmm (No. 191) is partially replaced by an Al atom. The hydrogen-uptake properties are usually enhanced in other AB(5) structures by aluminium substitution. YCu(5) does not show any hydrogen absorption, and the goal of the present work is to investigate whether aluminium substitution could expand the metal-atom lattice enough to provide better interstitial positions for hydrogen storage. However, no enthalpy change was observed up to 773 K under 3 MPa static H(2) pressure by differential thermal analysis (DTA) for the title compound. The compound does not show any significant hydrogen absorption/desorption in the pressure-composition isotherms (P-C-T diagrams) in the temperature range 298-673 K under 3.3 MPa H(2) pressure.