Nano-structural studies on Fe₃O₄ particles dispersing in a magnetic fluid using x-ray diffractometry and small-angle neutron scattering

Ferrofluid (magnetite/Fe₃O₄ magnetic fluid) is colloidal suspension containing Fe₃O₄ nanoparticles dispersed in a liquid carrier. In this work, Fe₃O₄ particles in the fluid have been prepared by a simple co-precipitation route. The nano-structural behaviors such as phase purity and crystal structure of magnetite particles in ferrofluid were studied by means of X-ray diffractometry (XRD). Meanwhile, the form and structure factors were investigated by small-angle neutron scattering (SANS) spectrometer. The XRD pattern confirmed a single phase of spinel cubic Fe₃O₄ structure. Further XRD data analysis revealed that the magnetite has a lattice parameter of 8.38 Å. The SANS data was fitted by applying a lognormal spherical calculation as a form factor and a mass fractal model as a structure factor. It showed that the magnetite ferrofluid has primary particles of 7.6 nm in diameter with fractal dimension of 1.2, which can be associated with chainlike structure. The chain-like structured Fe₃O₄ ferrofluid based on local natural iron sand in this work opens new opportunities to be applied for novel prospective applications.