Solvothermal synthesized monodisperse Fe3O4nanoparticles have been encapsulated with zinc sulfide shell through a simple ultrasonic-assisted aqueous-phase method under ambient environment. The monodisperse magnetic cores with average diameter of 180 nm were coated with zinc sulfide shelles (20~60 nm), in order to achieve a core-shell structure with both magnetic and luminescent properties. Structure, morphology and size of products were investigated in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The results display that the Fe3O4cores have been coated with ZnS shells Magnetic and optical properties of the nanocomposites were measured with vibrating sample magnetometer (VSM) and photoluminescence (PL) spectroscopy. Magnetic study reveals reduction of the saturation magnetization (Ms) for Fe3O4@ZnS nanocomposites compared with uncoated Fe3O4nanoparticles. Room temperature PL spectrum of the Fe3O4@ZnS samples shows two emission bands occurred at 389 and 292 nm, respectively. The bifunctional magentic-Optical materials can be used in biomedicine. Keywords: Fe3O4; ZnS; core-shell structure; nanocomposites
