Unusual Magnetic Properties of Size‐Controlled Iron Oxide Nanoparticles Grown in a Nanoporous Matrix with Tunable Pores

Fully loaded: A facile nanosieve approach for the preparation of Fe2O3 nanoparticles that have uniform and tunable sizes and are highly dispersed over a mesoporous support is achieved by the simple adjustment of the pore diameter of the template matrix (see picture). The nanoparticles are very small (6.5–9.0 nm) and show superior magnetic properties compared to pure Fe2O3 nanoparticles prepared without using a support.