Study on the kinetics of monodisperse iron oxide nanocrystal formation

PHYS 426

Soon Gu Kwon, kwonsoongu@hotmail.com, Taeghwan Hyeon, thyeon@snu.ac.kr, and Yuanzhe Piao. National Creative Research Initiative Center for Oxide Nanocrystalline Materials & School of Chemical and Biological Engineering, Seoul National University, 151-744 Seoul, South Korea
We studied the kinetics of the formation of iron oxide nanocrystals obtained from the solution-phase thermal decomposition of iron-oleate complex via the “heating-up” process. A thermogravimetric-mass spectrometric analysis and in-situ magnetic measurements using SQUID revealed that the thermal decomposition of iron-oleate complex generates intermediate species, which seem to act as monomers for the iron oxide nanocrystals. Extensive studies on the nucleation and growth process using size exclusion chromatography, the crystallization yield data, and TEM showed that burst of nucleation is followed by the rapid narrowing of the size distribution. We constructed a theoretical model to describe the “heating-up” process and performed a numerical simulation. The simulation results matched well with the experimental data. Through this theoretical work, we showed that the “heating-up” and “hot injection” processes can be understood within the same theoretical framework based on LaMer model in which they share the characteristics of nucleation and growth stages.