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

Laves phases of the type AB₂, 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 MgCu₂-type) or the C14 (hexagonal MgZn₂-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 (ZrB₂) 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.