Effect of Al substitution on the local environments and magnetic properties of partially nitrogenated (Er<inf>0.5</inf>Pr<inf>0.5</inf>)<inf>2</inf>Fe <inf>17</inf> permanent magnets

Extended x-ray absorption fine structure measurements of the Fe K, and Pr and Er LIII absorption edges, were carried out to elucidate the relationship between the local structure and magnetism in Al substituted, partially nitrogenated (Er0.5Pr0.5)2Fe 17 permanent magnets. We find that the nitrogenation acts to dilate both the Fe-Fe and the (Pr,Er)-Fe bonds, thus raising the TC via a magnetovolume effect. However, nitrogenation of Al-substituted samples acts to decrease the average Fe-Fe bond distance, thus reducing the exchange on the Fe sublattice and lowering TC relative to the nitrogenated parent compound. This is opposite to the trend measured in systems when N is absent. © 1998 American Institute of Physics.