Acta Chim. Slov. 43 (1996) 343-355.

THE RARE EARTH BASED INTERMETALLICS – A SCIENTIST’S PARADISE

Zelimir Blazina

Laboratory for Solid State Chemistry, Rudjer Boskovic Institute, POBox 1016, 10001 Zagreb, Croatia

Intermetallic compounds based on rare earth metals have drawn considerable interest in contemporary research due to their unique and diversified properties. In this paper some of our contributions to this field are presented. The variety of crystal structures often encountered in binary rare earth – transition metal systems are demonstrated with the examples of selected rare earth – noble metal systems. The influence of substitution of nickel by aluminium in the RENi₅ (RE = rare earth) alloys on the crystal structure and hydrogen sorption properties is also given. In these systems substitution proceeds up to RENi₂Al₃, with a structural change at the composition RENi₃Al₂. The hydrogen absorption is restricted to the ternary region and with a particular structure type. The hydrogen capacity and the equilibrium pressure decrease with increased content of aluminium. However, in the case of ErNi_5-xAl_x it was found that the hydrogen capacity increases and the equilibrium pressure decreases as the concentration of aluminium increases. The magnetic properties of rare earth based intermetallics are illustrated with the magnetic behavior of cerium in the CePt_5-xAl_x system. In this system single phase alloys exist up to CeNi₂Al₃ and are antiferromagnetic. Susceptibility follows a Curie-Wiess behavior with effective magnetic moments close to that for the Ce³⁺ ion, provided that a temperature-independent susceptibility is subtracted from the total susceptibility. A decrease in valency of cerium from above 3+ in CePt₅ to 3+ in CePt₂Al₃ is present.