Structural and magnetic characterization of 100-kGy Co⁶⁰ γ-ray-irradiated ZnFe₂O₄ NPs by XRD, W–H plot and ESR

Nanocrystalline spinel ferrite was prepared by sol–gel auto-combustion technique and sintered at 600 °C for 12 h. Single-phase cubic spinel structure of zinc ferrite was confirmed through X-ray diffractometry. Several structural and magnetic properties of ZnFe₂O₄ NPs were studied after Co⁶⁰ γ-irradiation with total gamma dose of 50 and 100 kGy. An average crystallite size was determined from the full width at half maximum of strongest reflection (311) by using Scherrer’s approximation. Williamson–Hall plot (graph against βcosθ and 4sinθ) was used to re-evaluate the measured crystallite size and to estimate the strain distribution in terms of η%. Lattice constant (α) initially increased slightly to 8.441 Å with γ-50 kGy and then decreased dramatically with total dose of γ-100 kGy. Frustrated behaviour in peak shift to lower and higher 2θ side can be seen in XRD after γ-irradiation to ZnFe₂O₄ NPs. FT-IR spectra confirmed the formation of ferrite phase and redistribution of cations in (A) and [B] sites of ZnFe₂O₄ spinel structure. In the first derivative peak of ESR spectroscopy, gyroscopic spitting factor (g-value) and linewidth (∆H_PP) were used to deliberate the γ-radiation damage in investigated ferrimagnetic nanoparticles. Experimental results revealed that the saturation magnetization (M _s), coercivity (H _c) and magneton number (n _B) of ZnFe₂O₄ NPs were found to be increased after gamma irradiation dose of γ-100 kGy.