Structure and magnetic properties of nanocrystalline cobalt ferrite powders synthesized using organic acid precursor method

Abstract

Nanocrystalline octahedra of cobalt ferrite CoFe 2O 4 powders were synthesized using the organic acid precursor route. The effect of the calcination temperature, Fe 3+/Co 2+ molar ratio, calcination time and type of organic acid (oxalic, benzoic and tartaric acids) on the formation, crystallite size, microstructure and magnetic properties was studied systematically. The Fe 3+/Co 2+ molar ratio was varied from 2 to 1.739 while the annealing temperature was controlled from 400 to 1000 °C for various periods from 0.5 to 2 h. The resulting powders were investigated using X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). XRD results indicate that a well crystallized, single spinel cobalt ferrite phase was formed for the precursors annealed at 600–800 °C for 2 h, using oxalic and tartaric acids as precursors for Fe 3+/Co 2+ molar ratio 1.818. The crystallite size of as-formed powders was in the range of 38.0–92.6 nm at different operating conditions. The calcination temperature and Fe 3+/Co 2+ molar ratio have a significant effect on the microstructure of the produced cobalt ferrite. The microstructure of the produced powders was found to be octahedra-shaped. The crystalline, pure cobalt ferrite powders with magnetic properties having a maximum saturation magnetization (76.1 emu/g) was achieved for the single phase at Fe 3+/Co 2+ molar ratio 1.818 and annealing temperature of 600 °C for 2 h using tartaric acid precursor.