Nonstoichiometric M-ferrite porous spheres: preparation, shape evolution and magnetic properties

We developed a simple one-pot solvothermal process to prepare porous M-ferrite (M=Ni, Zn, Co, Mn, Mg) magnetic spheres using different M2+ and Fe3+ with the introduction of dodecylamine. As-prepared ferrites were characterized in detail by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and selective area electron diffraction (SAED). XRD and EDS results showed that M-ferrites were nonstoichiometric in nature. Monodispersed magnetic ferrite spheres had a size distribution of 100–500 nm with different composition of M2+. Morphology evolution of ferrites upon reaction time and different metal doping has been studied. Furthermore, magnetic properties of M-ferrite spheres could be tuned by changing substituted metal cations. The influence of calcination on the phase and magnetic property was also investigated.