Substitution effects in M-type hexaferrite powders investigated by Moessbauer spectrometry

Significant improvements of the magnetic properties of M-type hexaferrites (SrFe12O19) can be achieved through partial substitutions with a rare-earth element and a transition metal. From this point of view, 57Fe Moessbauer spectrometry is a very powerful tool to determine the location of the substituted elements. We discuss here the effects on the Moessbauer spectrum of the substitution of a rare earth ion (Sm3+, Nd3+ or La3+) in the Sr2+ site, and the substitution of a metal ion (Co2+ or Zn2+) in the Fe3+ sites