Novel RMn₂ (R = Y, Er) hydrides with laves phase synthesized under hydrogen pressure

A novel hydride YMn₂H₆ has been synthesized from C15 Laves YMn₂ under hydrogen pressure. According to neutron powder diffraction experiments, YMn₂H₆ crystallizes in the Fm-3m space group with a = 6.708 Ǻ at 300 K. Thus, the initial C15 structure is strongly rearranged to form a structure in which the Y atoms and half of the Mn atoms statistically occupy the 8c site, whereas the other Mn atoms located in the 4a site are surrounded by 6 H atoms (24e). According to our knowledge, this type of behaviour has never been observed in hydrides derived from Laves phase intermetallics. A corresponding investigation of the synthesis of ErMn2H6 under high hydrogen pressure has been conducted.