engleski

Hydrogen Sorption Properties of the LaNi5-XGaX Alloys

A series of ternary alloys based on LaNi5 was prepared by substituting up to 50 at. % of nickel with gallium. X-ray powder diffraction revealed that the hexagonal structure of LaNi5 (CaCu5 type ; space group P6/mmm) is preserved in all ternary alloys and that the unit cell parameters increase with the gallium concentration. The alloys have been exposed to hydrogen gas and the pressure composition desorption isotherms for the alloy-hydrogen systems were determined. It was found that substitution of nickel with gallium decreases the hydrogen capacity and the hydrogen equilibrium pressure of the corresponding alloy-hydrogen system. The thermodynamic parameters of hydride formation, i.e., the entropy change, the enthalpy and the Gibbs free energy of formation have been derived from desorption isotherms for those alloy-hydrogen systems that exhibit plateau pressures.

hydrogen storage materials; intermetallics; X-ray diffraction

nije evidentirano