U(Fe1-xNix)AlHy system:: new hydride phases, structural and magnetic properties

We report the hydriding characteristics of U(Fe1-xNix)AlHx, with x = 0.85. It is found that (i) U(Fe0.15Ni0.85)Al can be hydrided to a maximum of yapproximate to2.4 and the hydride shows antiferromagnetic ordering with T(N)approximate to70 K, and (ii) new single phase orthorhombic hydrides can be stabilized for xgreater than or equal to0.85. From our hydriding and magnetic studies on all the compositions in this series of compounds, including our earlier work, it is found that irrespective of the magnetic state of the parent composition, the hydrides with ygreater than or equal to2 result in U-5f-electron localization and antiferromagnetic ordering. Structural and magnetic studies have also been carried out on the orthorhombic hydride phases and these are found not to order down to 2 K. (C) 2002 Elsevier Science B.V. All rights reserved.