Novel synthesis of nickel ferrite magnetic nanoparticles by an in‐liquid plasma

Magnetic nanoparticles of nickel ferrites were successfully synthesized by the in-liquid plasma method. The synthesis process is performed in three different solutions. The anode material is made of iron and nickel powder by Spark Plasma Sintering (SPS) process. By discharging on the anode’s surface in the solution, a plasma forms on the electrode surface, and nanosize particles detached from the electrode and immediately oxidized into a ferrite spinel. Spectroscopic, morphological, structural, and magnetic characterization showed that the electrolyte type significantly affects nanoparticle features. The X-ray diffraction of nanoparticles confirms the formation of spinel NiFe₂O₄, and the highest crystallinity has belonged to the nanoparticles synthesized with ethanol and sodium hydroxide. Based on the results, the particles synthesized in the optimum solution are spherical with an average size of ~ 10 nm, and their specific surface area is significantly enhanced to 55.237 m²/g. A ferromagnetic property with 89.75 Oe coercivity and a saturation magnetization of 42.27 emu/g has been measured for the synthesized powders at room temperature.