Structural, Mössbauer and magnetic study of Co1-xZnxFe2O4 (x = 0.0 − 0.56) nano ferrites.

We report on the synthesis of spinel Co_1-xZn_xFe₂O₄ (x=0.0-0.56) ferrites by sol-gel auto-combustion method. X-ray diffraction 'XRD', magnetic measurements were used to study compositional-dependence of structural, magnetic properties, connection among them. Mössbauer spectroscopy was used to identify non-magnetic-phase, its effect on magnetic properties. Single-phased nano spinel-ferrite formation is confirmed by XRD. Increasing Zn-content leads to structural modifications such as decrease of lattice parameter, grain diameter D_W-H, alteration of inversion parameter, disorder, tensile-strain, dislocation density, variation of A–O–B, A–O–A, B–O–B super-exchange-interaction and canting angles. Cationic distribution suggests that Fe³⁺,Co²⁺ ions reside on both A, B-sites, and with increasing Zn-content, B-site population of Fe³⁺, Zn²⁺ ions increases; while that of Co²⁺ ions decreases. Saturation magnetization shows noticeable dependence on canting angle suggests that the magnetization in the studied samples is described by Yafet-Kittel three-sub-lattice model. Coercivity H_c values are consistent with anisotropy, and its dependence on D_W-H suggests that the studied samples are inoverlap-region between multiple-domains/single-domain. Reduced-remanence indicate the variation of inter-grain magnetostatic-interaction, isotropic-behavior of multi-domain particles. Observed broad peaks in magnetization derivative with field suggest large-number of dislocations, more-uniform particle-size. Switching-field-distribution proposes potential application of the studied x=0.0 sample in high density recording, and sample with x=0.56 in targeted drug delivery. Mössbauer measurements confirm three-magnetic-components corresponding to A,B-sites, Fe3+ ions in grain boundaries/surface, Fe has 3+ oxidation state, and growing paramagnetic-doublet, alone does not explain the trend of M_s, suggesting that it is a collective-effect of structural-modification, presence of paramagnetic-doublet. [ABSTRACT FROM AUTHOR]