A Theoretical and Experimental Study of the Enthalpies of Formation of LaNi₅‐Type Compounds

Abstract

Abstract The heats of formation of LaNi 5 ‐type compounds are computed within a tight‐binding scheme for the d‐band. It is shown that the relatively large difference between the energy levels of the two elements is a dominant factor in the determination of the formation energy. The evolution of the energy level of the rare‐earth metal can explain the experimental behaviour of the heats of formation of the RNi 5 compounds along the rare‐earth series. In order to discuss the calculated results the enthalpies of formation of LaNi 5 , PrNi 5 , SmNi 5 , and YNi 5 are determined by a calorimetric method.