Magnetic field-induced cluster formation and variation of magneto-optical signals in zinc-substituted ferrofluids

Abstract

Fine magnetic particles (sizeffi100 Å ) belonging to the series Zn x Fe 1Àx Fe 2 O 4 were synthesized by cold co-precipitation methods and their structural properties were evaluated using X-ray diffraction. Magnetization studies have been carried out using vibrating sample magnetometry (VSM) showing near-zero loss loop characteristics. Ferrofluids were then prepared employing these fine magnetic powders using oleic acid as surfactant and kerosene as carrier liquid by modifying the usually reported synthesis technique in order to induce anisotropy and enhance the magneto-optical signals. Liquid thin films of these fluids were prepared and field-induced laser transmission through these films was studied. The transmitted light intensity decreases at the centre with applied magnetic field in a linear fashion when subjected to low magnetic fields and saturate at higher fields. This is in accordance with the saturation in cluster formation. The pattern exhibited by these films in the presence of different magnetic fields was observed with the help of a CCD camera and was recorded photographically. r

Approaches on Ferrofluid Synthesis and Applications: Current Status and Future Perspectives

“…19−21 Magnetite has higher magnetic properties 21 and is the preferred compound obtained from synthesis. In addition to magnetite and maghemite, ferromagnetic compounds composed of a mix of iron and oxidation state +2 metals such as cobalt, 22−27 zinc, 28,29 nickel, and manganese 22,23,30−33 are also used.…”

Enhanced shape anisotropy and magneto-optical birefringence by high energy ball milling in NixFe1−xFe2O4 ferrofluids

“…X-ray diffraction of the samples was recorded in an X-ray diffractometer (Rigaku Dmax-C) using Cu-Ka radiation (l=1.5406 Å ) [11]. Lattice parameter (a) was calculated assuming cubic symmetry [12].…”

Time dependence of light transmission in nanoparticle ferrofluids

“…In these studies, the observed time dependence of light transmission was attributed due to cluster formation. Magnetic liquids are known to exhibit cluster formation upon the application of external magnetic field [3,6]. Accordingly, a study of the time dependence of light transmission in magnetic liquids will hint the change in the fluid microstructure upon the application of external magnetic fields.…”