Nanoparticles-assembled ZnFe₂O₄ mesoporous nanorods for physicochemical and magnetic properties

Hierarchically one dimensional (1-D) mesoporous ZnFe₂O₄ rods with nanoparticles as their building blocks have been synthesized by the solvothermal approach. The influence of annealing temperature on structural, morphological, optical and magnetic properties was intensively investigated. X-ray diffraction was used to ascertain the phase purity of synthesized samples. To perceive the information on morphological and structural features, field emission scanning electron microscopy and high resolution transmission electron microscopy with energy dispersive spectroscopy was probed. It was observed that nanorods with high aspect ratio were obtained when treated at 600 °C (ZF600) annealing temperature as compared to 400 °C (ZF400). Fourier transform infra-red spectroscopy was resorted to gain the insight of bonding mechanism associated with ZF400 and ZF600. To enrich the study on material chemistry and defects, Raman spectroscopy and X-ray photoelectron spectroscopy was performed. Brunauer–Emmett–Teller envisioned the surface area of ZF400 and ZF600. It was found that surface area decreases with increase in annealing temperature. UV–Vis spectroscopy expounds that the optical band gap increases with annealing temperature from 3.0 to 3.3 eV for ZF400 to ZF600 respectively. Magnetic measurements were performed on vibrating sample magnetometer at room temperature and the results decipher the superparamagnetic nature of the synthesized material. Additionally, saturation magnetization was found to increase with annealing temperature.