Size dependent electromagnetic properties of Fe3O4 nanospheres

Different-sized Fe3O4 nanospheres (from ∼30 nm to ∼100 nm) were prepared via a solvent-thermal route by controlling the content of FeCl36H2O in the synthesis. The crystalline structure, surface morphology and magnetic properties of obtained Fe3O4 nanospheres were systematically characterized. Additionally, the complex permittivity and permeability were measured to simulate the electromagnetic absorption of different-sized Fe3O4 nanospheres from 0.5 to 15 GHz. The results indicated that the Fe3O4 nanospheres with an average size of ∼65 nm exhibited the strongest magnetic properties (saturation magnetization of 89.24 emu/g) and electromagnetic absorption (reflection loss of −30.37 dB at 9.68 GHz).