Cation distribution study of nanocrystalline NiFe2-xCrxO4 ferrite by XRD, magnetization and Mossbauer spectroscopy

The spinel ferrite systems NiFe2-xCrxO4 (with x = 0.0-1.0 in step of 0.2) were prepared by wet chemical co-precipitation method, using sulphates of respective metal ions. Formation of single phase spinel crystal structure of sample has been confirmed by X-ray diffraction method. Magnetic parameters such as coercivity and saturation magnetization are measured by employing vibrating samples magnetometer (VSM). The saturation magnetization and magneton number (n(B)) decreases with increase in Cr3- content x. The Mossbauer spectra taken at 300K and spectra are assigned to two strongly overlapping sextets corresponding to tetrahedral A sites and octahedral B sites. The cation distribution of ferrites system has been calculated by X-ray method, the behaviour of magnetization curve and Mossbauer spectra. The evaluation of cation distribution indicates that, in Cr-dominant region, few nickel ions occupies tetrahedral A sites which convert perfect inverse spinel to partially normal spinel structure. (c) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim