Structural relationships in complex hydrides of the late transition metals

Abstract

Abstract Literature data on complex hydrides of the late transition metals (groups 7–10), such as the hydrogen storage material Mg2NiH4, are reviewed with respect to order-disorder phase transitions and structural relationships. They are analysed in terms of crystallographic group-subgroup trees and their use in understanding the different crystal structures from a symmetry point of view is demonstrated. New data are presented on the low temperature behaviour of magnesium iridium hydrides and strontium rhodium hydrides studied by powder X-ray diffraction.