Synthesis and Characterization of Ferromagnetic Fe3O4-ZnO Hybrid Core-Shell Nanoparticles

Room-temperature synthesis of multifunctional core-shell nanostructures with iron oxide (Fe3O4) core and zinc oxide (ZnO) shell is described. High-resolution transmission electron microscopy revealed the occurrence of heteroepitaxial growth of a ZnO shell over the iron oxide nanoparticle core. The formation of the core-shell nanostructure was also evidenced by x-ray diffraction and x-ray photoelectron spectroscopy analyses. The core Fe3O4 nanoparticles exhibited superparamagnetic behavior at room temperature in an externally applied magnetic field. However, magnetic measurements of the core-shell nanoparticles revealed ferromagnetic behavior, originating from defect-induced ferromagnetism in the ZnO shell. The prepared core-shell nanoparticles also exhibited strong photoresponse while retaining ferromagnetic behavior at room temperature.