Interfacial coprecipitation to prepare magnetite nanoparticles: Concentration and temperature dependence

A novel interfacial coprecipitation method to prepare magnetite nanoparticles was proposed by us recently, which possesses advantages such as facility, Gram-scale synthesis and surface functionality. In this paper, the effects of precursors concentration and reaction temperature in interfacial coprecipitation method were systematically studied to evaluate the differences between classical and interfacial coprecipitation. It was found for first time that in both interfacial and classical coprecipitation there is a critical region of ferrous ion concentration to obtain magnetite at different amine concentrations, in which a phase of two-line ferrihydrite was considered to be an intermediate. Meanwhile, although the size of nanoparticles was not obviously varied by adjusting the reaction temperature, their dispersibility and saturation magnetization can be tailored. Besides, by comparing with classical coprecipitation, the mechanism in the interfacial coprecipitation was elucidated.