EPR study of Ni distribution in LaNi y Co 1– y O 3 solid solutions (0 ≤ y ≤ 0.25)

The distribution of Ni in LaNi y Co 1– y O 3 solid solutions was examined by means of EPR spectroscopy. For the assignment of the EPR signals, La 1– x Sr x CoO 3 oxides were used as reference for Co 3+ –Co 4+ magnetic clusters. For the oxides heated at 600 °C, the EPR spectra of LaNi y Co 1– y O 3 consist of a signal due to magnetic Ni clusters, while the oxides prepared at 700 °C display an EPR signal due to ferromagnetic coupled Co 3+ and Co 4+ impurity ions that do not form magnetic clusters. LaNi y Co 1– y O 3 samples prepared at T > 700 °C are EPR “silent”. The effect of the preparation method and the preparation temperature on the formation of Ni clusters is discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)