Size Dependent Heating Efficiency of Iron Oxide Single Domain Nanoparticles

The iron oxide nanoparticles have been synthesized by coprecipitation and solvothermal reduction methods. The particles obtained differ in size, the mean size of particles coprecipitated is of 13 nm and the particles, prepared by solvothermal reduction method have a size of 20 nm. Both kinds of nanoparticles demonstrate narrow particles sizes distribution. The particles which are prepared by coprecipitation method have narrow particles sizes distribution with mean size diameter of 13 nm and the particles, prepared by solvothermal reduction method have a size of 20 nm. The X-ray diffraction data analysis revealed that highly crystalline and single-phase magnetite nanoparticles are formed by solvothermal reduction technique, whereas coprecipitation leads to the formation of multi-phase composition of a magnetite (72%) and maghemite (28%). According to the size of nanoparticles obtained, they are in superparamagnetic state for iron oxides. The saturation magnetization of solvothermal prepared particles is higher than those for coprecipitated due to their higher crystallinity and phase purity. Nevertheless, the glycerol dispersion of particles coprecipitated shows higher SLP values than the dispersion of the particles, synthesized by solvothermal reduction method. The heating efficiency of nanoparticles based dispersions is explained by the particles size effect and properties of carrier medium.