Neither Goodenough ionic model nor Zener polaron model for Bi0.5Ca0.5Mn1−xNixO3−δ system

The magnetic susceptibilities of three Bi0.5Ca0.5MnO3−δ compounds synthesised by three different methods were characterised and analysed. Large magnetic Mnx clusters (x ≥ 4) were considered to explain the high value of the Curie–Weiss constant. Unlike previous studies on similar systems, Goodenough ionic model or Zener polaron model is not suitable. In all cases, cluster behaviour is observed at low field and at low temperature. The influence of the oxygen stoichiometry and the homogeneity of the cation distribution depending on the method of the synthesis used is discussed. Finally, the effects of nickel doping on the magnetic properties were studied and the cluster behaviour was confirmed. The distribution in size of the clusters depends on the amount of nickel and it induces a glassy magnetic behaviour.

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