| The development of stable membranes for H2 separation is one of the main challenges associated with the cost effective production of high-purity H2. The lifetime of current membranes is limited. Failure often occurs owing to deformation and fracture caused by the large specific volume change during the hydride formation. The membranes performance depends on hydrogen solubility and diffusivity, both are determined by the nature of the alloying elements i.e. concentration and distribution in the metal lattice, and the (local) metal environment of the hydrogen atoms w. A statistical thermodynamic framework has been set-up that incorporates the interactions of a multi-component host metal alloy with interstitials (hydrogen). To be able to apply the thermodynamic model for systems for which no experimental data are available ab initio calculations are required. Energy calculations based on the effective cluster interaction and ground states of multi-component alloys are successful but very time consuming. Therefore a new approach, that is much faster, will be used. The method is based on the direct calculation of the energy of the independent cube clusters by VASP. |
