Structural and Magnetic Properties of NiFe2-2xSnxCuxO4

The substituted nickel ferrite (NiFe2-2xSnxCuxO4, x=0, 0.1, 0.2, 0.3) was prepared by the conventional ceramic method. The effect of substitution of Fe3+ ions by Sn4+ and Cu2+ cations on the structural and magnetic properties of the ferrite was studied by means of Fe-57 Mossbauer spectroscopy, alternating gradient force magnetometry (AGFM) and Faraday balance. Whereas undoped NiFe2O4 adopts a fully inverse spinel structure of the type (Fe)[NiFe]O-4, Sn4+ and Cu2+ cations tend to occupy octahedral positions in the structure of the substituted ferrite. Based on the results of Mossbauer spectroscopic measurements, the crystal-chemical formula of the substituted ferrite may be written as (Fe)[NiFe1-2xSnxCux]O-4, where parentheses and square brackets enclose cations in tetrahedral (A) and octahedral [B] coordination, respectively. The Neel temperature and the saturation magnetization values of the NiFe2-2xSnxCuxO4 samples were found to decrease with increasing degree of substitution (x). The variation of the saturation magnetization with x measured using the AGFM method and that calculated on the basis of the Mossbauer spectroscopic measurements are in qualitative agreement. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.