CRYSTAL-STRUCTURE AND HYDRIDING BEHAVIOR OF LANI5-YSNY

The phase composition and structures of several LaNi.5-ySny alloys with y < 0.3 have been studied using X-ray diffraction. These alloys are found to retain the hexagonal symmetry of LaNi5 with increases in both lattice parameters. Since the Sn atoms are larger than the Ni atoms which are being replaced, small distortions are likely to arise in the positions of the Ni atoms located at the midplane 3g sites that are above and below the Sn atoms. Effects of variations in alloy stoichiometry and hydrogen absorption/desorption under different conditions are also reported.