Solution combustion synthesis of iron-based magnetic nanoparticles: influence of inert gas pressure

We report the synthesis of iron oxide nanoparticles using solution combustion synthesis, focusing on the controlled manipulation of material characteristics, such as particle size, phase composition, and magnetic properties, by applying external inert gas pressure. It was shown that variation of nitrogen gas pressure in the reactor in the range 0.1 to 1.1 MPa changed the time-temperature history of the process and resulted in the gradual change of phase composition of the fabricated materials along the FeO → FeO∙Fe₂O₃ → Fe₂O₃ route. The particle size varied in the 50–400 nm range, with a maximum for powder synthesized at a pressure of 0.25 MPa. For magnetic fluid hyperthermia, the critical parameter is specific loss power. It was demonstrated that this parameter can be optimized by gas pressure variation. The maximum specific loss power measured under conditions suitable for magnetic hyperthermia (magnetic field 33.5 mT and frequency 259.6 kHz) appears to be 174 W/g. The proposed innovative approach is an effective tool for controlling the synthesis of various nanoparticles with desired properties.