Simulation and experimental study of cuboid and spherical magnetic Fe3O4 nanoparticles prepared with NaOH and NH4OH

Abstract

AbstractA molecular dynamics study is done on cuboid and spherical Fe3O4 magnetic nanoparticles (NPs) to investigate qualitatively the influence of the molecules NH4OH and NaOH on their binding energy. This is done to determine the stability and therefore likely shape (morphology) and size of the synthesized NPs when these molecules are used as stabilizing agents. We show through molecular dynamics (MD) that small, spherical NPs synthesized with NH4OH, and large, cuboid NPs synthesized with NaOH, are the most stable NP systems and therefore the most likely outcome of a synthesis experiment. Furthermore, we synthesize these systems under similar conditions as predicted and find that when NaOH is used large (29 ± 2 nm), cuboid NPs are formed and when NH4OH is used, small (11 nm ± 2 nm), spherical NPs are formed. The role of pH is further investigated using the desorbed (and unadsorbed hydroxyl groups) as indicators of pH. The magnetic NPs are then synthesized via the co-precipitation method and the resulting NPs characterized for crystallinity, morphology, size and magnetic properties.