Hydrogen storage properties of non-stoichiometric AB2-type metal hydride①
(Beijing General Research Institute for Non-ferrous Metals, Beijing100088, P.R.China)
Abstract: Hydrogen storage properties of non-stoichiometric AB2-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 ofxvalue. The free-energy change (ΔG) between hydriding and dehydriding process has a significant effect on the hysteresis of the alloys. Thep-c-tplateau region becomes narrow and the reversible hydrogen capacity decreases with the increase ofxvalue (x>0.1), although the hydrogen absorption capacity increases. The alloy withx=0.1 shows the optimum hydrogen storage properties.
Key words: hydrogen storage property; substoichiometric alloy; hysteresis effect