Study on the optically linear birefringence and dichroism properties of Fe3O4 magnetic nanoparticles

We adopt an improved co-precipitation method to prepare the Fe3O4 magnetic nanoparticles (MNPs). Influence factors such as the reaction temperature, the pH value of the solution, and the Fe3+/Fe2+ molar concentration are considered. Via the transmission electronic microscope and X-ray diffractometry, we characterize the dispersibility and size of the products. The reaction temperature and the pH value of the solution have a great influence in the dispersibility and size of MNPs. The diameter of Fe3O4 MNP, produced under Fe3+/Fe2+ molar concentration of 0.25 mole/l and molar ratio of 1.9:1, the reaction temperature is 80 °C, and the pH value reaches 9, is close to 11 nm. Above all, considering the variation of molar concentrations in Fe3+/Fe2+, the linear birefringence and dichroism of the kerosene-based ferrofluids are investigated by a Stokes polarimeter.