Studies on the microwave assisted and conventional combustion synthesis of Hibiscus rosa-sinensis plant extract based ZnFe2O4 nanoparticles and their optical and magnetic properties

Nanocrystalline ZnFe2O4 samples were synthesized by both conventional combustion method (CCM) and microwave assisted combustion method (MCM) using Hibiscus rosa-sinensis plant extract for comparison purpose. The prepared ZnFe2O4 samples were characterized by X-ray diffraction (XRD), Rietveld analysis, Fourier transform-infrared spectrophotometer (FT-IR), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, and vibrating sample magnetometer (VSM). The formation of single phase ZnFe2O4 was confirmed by XRD and FT-IR. The lattice parameter was calculated by Rietveld analysis. The change in the particle size ranges from 372.0 to 541.7 nm and 23.4 to 48.5 nm respectively for the conventional and microwave methods and has been clearly shown by HRSEM. UV-visible diffuse reflectance spectroscopy is used to measure the band gaps of ZnFe2O4, which is about 2.1 eV. Single phase ZnFe2O4 emits the photoluminescence bands at 486, 530, 542, and 566 nm. The magnetic properties of the synthesized ZnFe2O4 nanoparticles were investigated by VSM studies and the hysteresis loops were studied at room temperature. The saturation magnetization (Ms) of ZnFe2O4-CCM (63.61 emu/g) is lesser than that of ZnFe2O4-MCM (255.7 emu/g). ZnFe2O4 nanoparticles prepared by the microwave assisted combustion method were found to have higher surface area and lower crystallite size than ZnFe2O4 nanoparticles prepared by the conventional combustion method.