On structural model of AB5-type multi-element hydrogen storage alloy

Abstract

The present study is focused on the development of a structural model for multi−element AB5−type alloy which can correlate the hydrogenation characteristics with structural parameters. At present no such model is available, which can predict the trend of hydrogenation properties like hydrogen storage capacity, heat of formation and plateau pressure of multi−element hydrogen storage material. It is done by trial and error method. In present investigation efforts are made to correlate atomic radius of substituted elements with heat of formation of hydride, plateau pressure and hydrogen storage capacity by calculating equivalent radius of B (rB*) in multi−element composition, contraction in A−B bond, radius of voids and ratio of rA with rB*. The heat of formation decreases and hydride stability increases with increasing value of rB* and contraction in A−B bond. While hydrogen storage capacity decreases with increasing value of rB* and contraction in A−B bond. Based on this, correlation between thermodynamic and structural properties has been established and structural model has been developed.