Crystallographic study of LaNi5-xSnx (0.2 <= x <= 0.5) compounds and theirhydrides

The structural properties of tin substituted LaNi5 compounds and correspond ing deuterides have been investigated by single crystal X-ray and neutron p owder diffraction. Tin is found to substitute nickel exclusively on site 3g of space group P6/mmm. No other significant disorder occurs in the structu re. At tin contents of x=0.4 and x=0.5, the crystal structures of the deute rides do not significantly deviate from those of other metal substituted La Ni5 deuterides. At a tin content of x=0.2, with higher deuterium content, h owever, a symmetry decrease to non-centrosymmetric space group P6mm is obse rved due to partial deuterium ordering. (C) 1999 Elsevier Science S.A. All rights reserved.