HYDROGEN ABSORPTION IN SOME COMPOUNDS OF MOSI2-TYPE STRUCTURE

X-ray and neutron diffraction have been used to study the hydrogen (deuterium) absorption in the intermetallic compounds Zr//2Pd and Ti//2Cu both having the tetragonal MoSi//2-type structure. Zr//2Pd reacts with hydrogen at room temperature to form a hydride of composition Zr//2PdH//x (x yields 4. 75). On absorption the c axis expands until x equals 1. 0. This is ascribed to the occupation of the octahedral O//B sites with five zirconium and one palladium nearest neighbors. At about 400 degree C a new high-temperature hydride phase is formed.