Hydrogen storage properties of non-stoichiometric AB2-type metal hydride

Hydrogen storage properties of non-stoichiometric AB(2)-type alloys, Ti0.8Zr0.2(MnCrvFe)(2-x)(x = 0, 0.1, 0.2, 0.3), have been studied. The results show that the structures of the substoichiometric alloys can be described using the replacement model, that is, some A-side atoms occupy the primary B-side atom positions. The equilibrium pressures of the alloys decrease gradually and the hysteresis effect between hydriding and dehydriding process decreases with the increase of x. value. The free-energy change (Delta G) between hydriding and dehydriding process has a significant effect on the hysteresis of the alloys. The p-c-t plateau region becomes narrow and the reversible hydrogen capacity decreases with the increase of x value (x>0.1), although the hydrogen absorption capacity increases. The alloy with x = 0.1 shows the optimum hydrogen storage properties.