Crystal structure, electron-to-atom ratio and hydrogen storage capacity of zirconium based intermetallic laves phases

Abstract

Laves phases of the type AB 2, where A is zirconium, have potential for use as hydrogen storage materials. These Laves phases have one of two different crystal structures, namely the C15 (cubic MgCu 2-type) or the C14 (hexagonal MgZn 2-type) Strukterbericht types. Data are presented on the lattice parameters for the two phases and relationships are developed between the lattice parameters of the two phases both for the binary (ZrB 2) and the pseudobinary (Zr(B′ xB″ 1−x)2) Laves phases. Electron-to-atom ratios are calculated for both the binary and pseudobinary Laves phases and these are related to hydrogen storage capacity (hydrogen-to-metal ratio, H/M). The hydrogen-to-metal ratio is shown to decrease with increasing electron-to-atom ratio.