Effects of volume expansion and electron correlation in some R(Fe,M)12 compounds (M=Nb, Ti, V) and their nitrides

Abstract In the present paper, a study of the effect of the volume change on the Curie temperature ( T C ) of R(Fe,M) 12 (M=Nb, Ti and V) due to nitrogenation has been performed. The dln T C /dln V values were derived by comparing the Curie temperatures and volumes before and after nitrogen. Our results indicate that the relationship between dln T C /dln V and the Curie temperature T C agrees with an itinerant-model formalism. The effects of volume expansion and the increasing electron correlation play important roles in the enhancement of the Curie temperature upon nitrogenation of intermetallic compounds.