Hydrogen absorption properties of intermetallic compounds in the Au-Zr binary system

The present work reports about hydrogen absorption properties of four intermetallic compounds Au₂Zr, Au₁₀Zr₇, AuZr₂ and AuZr₃ in the Au-Zr binary system, which were studied by means of differential scanning calorimetry (DSC), hydrogen-storage capacity measurement and powder X-ray diffraction (XRD). A single exothermic peak, which is assigned to hydrogen absorption, appeared at a lower temperature for the intermetallic compound with increasing Au content, indicating a catalytic effect of gold on hydrogenation process; the amount of the exothermic heat linearly increased as a function of Zr content regardless of different structure between AuZr₃ (cubic) and other intermetallic compounds (tetragonal). Hydrogen-storage capacity measurement has also confirmed that the intermetallic compounds with higher Zr content afford more hydrogen-storage capacity. Powder XRD confirmed that no structural change was induced under the present hydrogenation conditions, but only a solid solution with hydrogen was formed for Au₂Zr, Au₁₀Zr₇ and AuZr₂. On the other hand, an unidentified hydride phase was formed in coexistence with the solid solution with hydrogen for cubic AuZr₃.