Volume effects on the magnetic properties of R2Fe17-based quasiternary compounds

Abstract

Structure and magnetic properties of the R2Fe17-based quasiternary compounds (R=Sm, Er, Gd, Y, Pr, Nd; M=Al, Ga) and their nitrides have been investigated. The saturation magnetization of R2Fe17−xMx compounds decreases with the increasing M content, while the M concentration dependence of the Curie temperature exhibits a maximum at about x=3.0 for the parent compounds. By nitrogenation the lattice parameters, the saturation magnetization, and the Curie temperature all have a corresponding increase compared with the parent alloys. The volume effects on the Curie temperature of these compounds have been studied. The d ln Tc/d ln V values were derived by comparing the change of the Curie temperature and volume before and after nitrogenation and show a linear dependence on the Curie temperatures for these systems investigated. This behavior can be quite well understood in terms of a combined model of localized and itinerant electrons suggesting more than 90% d electrons are localized, The same conclusion can be obtained from a analysis of the exchange field Hex dependence of the iron sublattice magnetization in the R2Fe17 compounds and their nitrides, and the iron proportionality constant VFe before and after nitrogenation.