Synthesis and characterization of Fe3O4@ZnS and Fe3O4@Au@ZnS core–shell nanoparticles

Abstract In the present work we report new assets on the synthesis and characterization of magnetite based core–shell nanoparticles such as Fe 3 O 4 @ZnS and Fe 3 O 4 @Au@ZnS. The composites were prepared by seed mediated growth which consist in a sequential growth of a second or third component on a preformed magnetite seeds in the presence of sodium laurylsulphate additives with essential role in growth and aggregation of nanoparticles. Evolved gas analysis (EGA) coupled with FT-IR was used in order to evidence the stages of ZnS shell formation. XRD studies were used for the structural characterization while high resolution transmission electron microscopy gave information concerning morphology and size distributions of nanoparticles. Qualitative and quantitative compositional analysis of samples was made by X-ray photoelectron spectroscopy (XPS). All the samples showed magnetic response due to the superparamagnetic behavior of magnetite cores. Increased saturation magnetization was determined for Fe 3 O 4 @ZnS samples. A significant photoluminescence (PL) enhancement was also observed as a result of Fe 3 O 4 :Zn 2+ molar ratio decrease. Additional PL increased response was realized by inserting a gold shell between the magnetite core and ZnS outer shell. Considerations regarding both PL and magnetization enhancements are also presented.