Abstract
Ferrimagnetic oxides may contain single or multi domain particles which get converted into super paramagnetic state near a critical size. To explore the existence of these particles, we have made Mossbauer and magnetic studies of Cu2+ substitution effect in CoFe2-xO4 Ferrites (0.0, 0.1, 0.2, 0.3, 0.4, and 0.5). All the samples have a cubic spinet structure with lattice parameters increasing linearly with increase in Cu content. The hysteresis loops yield a saturation magnetization, coercive field, and remanent magnetization that vary significantly with Cu content. The magnetic hysteresis curves shows a reduction in saturation magnetization and an increase in coercitivity with Cu2+ ion substitution. The anisotropy constant, K-1 is found strongly dependent on the composition of Cue-' ions. The variation of saturation magnetization with increasing Cu2+ ion content has been explained in the light of Neel's molecular field theory. Mossbauer spectra at room temperature shows two ferrimagnetically relaxed Zeeman sextets. The dependence of Mossbauer parameters such as isomer shift, quadrupole splitting, line width and hyperfine magnetic field on Cu2+ ion concentration have been discussed. (C) 2016 Elsevier B.V. All rights reserved.