Figure 5.

Time-evolution of Porod constant and Invariant for “Large” NP synthesis. The Porod constant (black crosses) and Invariant (red triangles) of the SAXS data recorded for “Large”-core synthesis heated at 3 K/min. The concerted increase during the heat-up phase corresponds to the formation of the iron oleate complex followed by burst nucleation of polyiron oxo clusters shortly after the final temperature of 290 °C is reached. These clusters are consumed as monomers for the core growth, which yields a decrease in Porod constant (internal area), while the Invariant increases during nanoparticle growth due to an increase in scattering contrast.