We performed a set of experiments using a direct imaging method to investigate the diffusion process of iron oxide, Fe2O3, nanoparticles. We studied concentration fluctuations that move against the concentration gradient and induce disturbances in the interface between the iron oxide suspension and water in the sample cell. Using this imaging method in combination with the differential dynamic algorithm for image processing, we are able to extract information about the power, size, and lifetime of the fluctuations. We performed this experiment both in the presence and in the absence of a 4.2 mT magnetic field. We find that the power and size of the fluctuations diminish in the presence of a magnetic field, as indicated by the change in slope of the structure factor from approximately -4 to -3, for q < qc. Furthermore, we find that after the removal of the magnetic field, their power and size are still damped beneath those we observed during free diffusion, indicating that the nanoparticles are at least still slightly magnetized. From the lifetime of the fluctuations, we determined the diffusion coefficients of the nanosuspension in each environment.
Rice, Ashley E. and Oprisan, Ana
"Investigation of Iron Oxide Nanocolloidal Suspension Diffusion Using a Direct Imaging Method,"
Journal of the South Carolina Academy of Science: Vol. 15:
2, Article 5.
Available at: https://scholarcommons.sc.edu/jscas/vol15/iss2/5