Use of Extended X-Ray Absorption Fine Structure in the Characterization of TiFe + x wt.%Zr (x = 1, 2, and 4)

For a large-scale utilization of hydrogen as an energy vector, a safe, low-cost, and practical way to store hydrogen must be developed. Because of their high volumetric density and low temperature of operation, metal hydrides are an attractive solution. The alloy TiFe is currently used for some practical applications, but the first hydrogenation is too slow. One way to improve the first hydrogenation kinetic is to add Zr during melting. However, the localization of the zirconium atom in the crystal structure is not clear. The EXAFS (extended X-ray absorption fine structure) technique is ideal as it offers some insight into the atomic surroundings of the zirconium and titanium atoms. We found that, upon zirconium inclusion, the Ti–Ti distance increases. This may increase the volume of the interstitial states and also create new ones, thus improving the hydrogenation kinetics.