Rare earth iron based magnetic materials with the Th/sub 2/Zn/sub 17/-type structure

The influence of the substitution mode on the magnetic behavior in RE/sub 2/Fe/sub 17/ has been investigated as a function of (a) the metal substitution (Fe replaced by Mn, Al, Ga) and (b) the accommodation of interstitial carbon atoms. X-ray powder analysis demonstrated consistency with the rhombohedral Th/sub 2/Zn/sub 17/-type structure in all cases. In correspondence with the resulting volume expansion, Curie temperatures tend to increase as a result of an enhanced ferromagnetic coupling mechanism. Sm/sub 2/Fe/sub 17-x-y/Mn/sub x/ (Al,Ga)/sub y/C/sub 3-z/, however, is the only system where substitution of iron in Sm/sub 2/Fe/sub 17/ 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.<
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