This would critically affect the magnetic properties ofnanosized particles and the Ms is decreased 35% comparing toformer reactions. So it is necessary to introduce N2 gas in thesynthesis to avoid the unwanted oxidation. Also, if the alkalisources are poured as quickly as possible into the ironicsolution under vigorous stirring conditions, black colloid canbe obtained but the size distribution is wide and someprecipitation is found after several weeks. This indicates thatthe rate of nucleation and crystalline growth are highindicating that the sizes of the particles are not properlycontrolled [56]. In terms of simplicity of the synthesis method,co-precipitation is the preferred route. In this method, thereaction temperature and time are lower than other methodssuch as thermal decomposition and hydrothermal. Also,solvent is environmental friendly (water) besides the reactionyield is high and scalable. But, size distribution is relatively