Structural, optical, magnetic and anti-bacterial properties of green synthesized spinel zinc ferrite by microwave-assisted method

Spinel structured zinc ferrite (ZF) has been green synthesized using microwave-assisted solution combustion method. Toxic free Hibiscus leaves extract was used as a reducing agent in the synthesis process. Rietveld refinement analysis of high-resolution X-ray diffraction (XRD) pattern confirmed that the ZF has cubic spinel structure with the average crystallite size of 10.47 nm. Agglomerated spherical shapes were observed in green synthesized spinel ZF by scanning electron microscope. The estimated average particle size was found to be 11.52 nm by high resolution transmission electron microscopy imaging. The Zn, Fe and O are the main elements present in spinel ZF, analysed from energy dispersion X-ray analysis. Tetrahedral and octahedral lattice sites which are related to Zn-O and Fe-O bonds were identified by Fourier transform infra-red and Raman spectra. The estimated optical energy bandgap of spinel ZF is found to be 2.17 eV using diffuse reflectance spectroscopy. The Vibrating sample magnetometer results showed single domain superparamagnetic nature of spinel ZF at room temperature. In addition, antibacterial properties of spinel ZF were tested using agar dispersion and agar well diffusion methods on gram negative bacteria Escherichia coli DH5 & alpha;, after 24 h the bacterial growth completely inhibited.

Automated summary

Spinel structured zinc ferrite (ZF) was synthesized using a green method with microwave-assisted solution combustion and a non-toxic reducing agent from hibiscus leaves extract. Analysis confirmed the cubic spinel structure of ZF with an average crystallite size of 10.47 nm. Scanning electron microscopy revealed agglomerated spherical shapes and transmission electron microscopy imaging estimated an average particle size of 11.52 nm. Zn, Fe, and O were the main elements present in the spinel ZF, as analyzed by energy dispersion X-ray analysis. Fourier transform infrared and Raman spectra showed the presence of tetrahedral and octahedral lattice sites related to Zn-O and Fe-O bonds. Diffuse reflectance spectroscopy indicated an optical energy bandgap of 2.17 eV for spinel ZF. Vibrating sample magnetometer results demonstrated the superparamagnetic nature of spinel ZF at room temperature. Antibacterial tests showed complete inhibition of bacterial growth of Escherichia coli DH5α after 24 hours.