Structural and magnetic properties of equiatomic rare-earth ternaries

Hydrogenation was found to be a strong tool for modification of magnetic pr operties and crystal structure of the RENiAl intermetallic compounds. Non-u niform expansion of the unit cell due to incorporation of hydrogen leads to an orthorhombic distortion of the original ZrNiAl-type hexagonal structure . Hydrogenation also largely suppresses magnetic order in all studied compo unds: it weakens exchange interactions, lowers ordering temperatures and mo difies magnetic phase diagrams. A series of hydrides with lower H concentra tion was studied, as well, and non-continuous variation of their properties with reducing H content indicates that the main effect of hydrogenation is not of geometrical character but due to the Variation of electronic densit y. (C) 1999 International Association for Hydrogen Energy. Published by Els evier Science Ltd. All rights reserved.