RARE-EARTH IRON BASED MAGNET MATERIALS WITH THE TH2ZN17-TYPE STRUCTURE

The influence of the substitution mode on the magnetic behavior in RE2Fe17 has been investigated as a function of (a) the metal substitution (Fe replaced by Mn/Al, Ga) and (b) the accomodation of interstitial carbon atoms. X-ray powder analysis proved in all cases consistency with the rhombohedral Th2Zn47-type structure (space group R3m). In correspondence with the resulting volume expansion, Curie temperatures tend to increase as a result of an enhanced ferromagnetic coupling mechanism. Sm2Fe.17-x-yMnx(A1, Ga)yCa-z, however, is the only system where substitution of iron in Sm2Fe17 by Mn, Al, Ga and/or carbon leads to an anisotropy change from easy plane to easy axis geometry. Magnetization values are strongly reduced due to a change of collinear ferromagnetism to a ferrimagnetic type of order of the various magnetic sublattices. © 1990 IEEE