Cr content-dependent modification of structural, magnetic properties and bandgap in green synthesized Co–Cr nano-ferrites

Abstract

Honey green synthesis of CoCrxFe2−xO4 (x = 0.0 − 1.0) ferrites with increasing Cr content was done by sol-gel auto-combustion method, without any post-preparation thermal treatment. Nanocrystalline nature (grain diameter range between 12.2 nm and 27.9 nm) of the studied samples is confirmed by X-ray diffraction (XRD) data. Observed modification of magnetic properties can be understood in terms of Cr addition induced changes in degree of inversion, modification of disorder affecting A–A, A–B, B–B interaction, re-distribution of cations on A, B sites in the spinel lattice. Grain size (D)-dependent coercivity (Hc) shows that the studied samples lie in the region with overlap between single- and multi-domain regions. Achieved magnetic properties in the studied honey green synthesized samples have significance for self-regulating hyperthermia applications. Results as well reveal modification of bandgap, and would be of use for applications, where minor bandgap tuning is required. Antistructure modeling provides information on the types of surface-active centers.