GAS-PHASE H-2 ABSORPTION AND MICROSTRUCTURAL PROPERTIES OF LANI5-XGEXALLOYS

Metal hydride alloys were prepared based on the LaNi5 formula by subst ituting 0-10 at.% of Ge for Ni. Crystal lattice parameters were obtain ed from X-ray diffraction patterns of each alloy. Hydrogen pressure-co mposition-temperature isotherms were measured for these LaNi5-xGex (0 less than or equal to x less than or equal to 0.5) alloys at temperatu res ranging 296 to 348 K. These isotherms were used to determine therm odynamic parameters for hydrogen absorption and desorption. The unit c ell volumes increase, and the plateau pressures decrease, with increas ing Ge substitution. Isotherms and capacities from gas-phase absorptio n are comparable to those of LaNi5-xSnx.