Structural and Magnetic Properties of NiFe2−2xSnxCuxO4

Abstract The substituted nickel ferrite (NiFe 2−2 x Sn x Cu x O 4 , x =0, 0.1, 0.2, 0.3) was prepared by the conventional ceramic method. The effect of substitution of Fe 3+ ions by Sn 4+ and Cu 2+ cations on the structural and magnetic properties of the ferrite was studied by means of 57 Fe Mossbauer spectroscopy, alternating gradient force magnetometry (AGFM) and Faraday balance. Whereas undoped NiFe 2 O 4 adopts a fully inverse spinel structure of the type (Fe)[NiFe]O 4 , Sn 4+ and Cu 2+ 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)[NiFe 1−2 x Sn x Cu x ]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 NiFe 2−2 x Sn x Cu x O 4 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.