Magnetic properties of γ-Fe₂O₃ nanoparticles

We produced maghemite (γ-Fe₂O₃) nanoparticles with average particle diameters of 6, 7, and 12 nm and investigated their magnetic properties. The structure was determined to be face centered-cubic with a lattice constant of a = 8.350±2 Å, similar to the bulk material for all samples. We observed that the γ-Fe₂ nanoparticles, with average particle diameters of 6 and 7 nm, were superparamagnetic at room temperature with blocking temperatures of 138 and 168 K, respectively. Those with an average particle diameter of 12 nm are ferrimagnetic at room temperature.