Linear birefringence and dichroism in Fe3O4 magnetic nanoparticles

Abstract

We adopt an improved co-precipitation method to prepare the Fe 3O4 magnetic nanoparticles (MNPs). Influence factors such as surfactant amount, stirring speed, dispersion mode, and Fe 3+/Fe2+ molar ratio are considered. Using the TEM and XRD, we characterize the dispersibility and size of the products. The appropriate values of experimental parameters are determined, such as stirring speed is 1,000 rpm in titration, simultaneous ultrasonic vibration and mechanical stirring in titration and surface coating, and surfactant amount of oleic acid is 1.2 ml for Fe3+/Fe2+ molar ratios including 1.7, 1.8, and 1.9. The average diameters of these Fe3O4 MNPs are determined around 11 nm by XRD analysis. In addition, the saturation magnetization for the MNP produced by Fe3+/Fe2+ molar ratio as 1.7 is 50.17 emu/g with near paramagnetism. Above all, the linear birefringence and dichroism of the kerosene-based ferrofluids are investigated by a developed Stokes polarimerter. Finally, compared to the results with those for a commercial product and the influences of particle size distribution and magnetization are discussed. © The Society for Experimental Mechanics, Inc. 2014.