Shape-controlled synthesis of Fe3O4 nanocrystals with incontinuous multicavities

In the solvothermal synthesis process, the effect of NaOH dosages of from 0.3 g to 4.0 g on the morphology evolution(from nanoparticles to octahedra) of Fe3O4 crystals was carefully investigated. Meanwhile, the growth process of Fe3O4 crystals at different reaction time was also investigated. Furthermore, it has been found that the particle size and crystallinity of Fe3O4 crystals can be controlled by the dosages of NaOH. In this paper, the increases of both the reaction time and the NaOH concentrations correspond to a minimization process of surface energy for Fe3O4 crystals. During the synthesis process, the addition of N2H4·H2O and ethylene glycol in the magnetite not only facilitated the narrow distribution of particle size but also contributed to the formation of incontinuous multicavities with a diameter of about 5 nm.