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Solid-state synthesis of ZnS nanoparticle via mechanical milling process

M.S.Al-Kotb, H.Selim, H.H.Amer, M.M.Khalil, M.F.Kotkata

Zinc sulfide (ZnS) quantum dots (QDs) were prepared via a novel solid– state reaction by milling appropriate amounts of zinc acetate and thioacetamide at room temperature. The structural nature and optical properties of the as-synthesized nanoparticles were characterized by using:X-ray diffraction (XRD), energy dispersive X-rays analysis (EDX), transmission electronmicroscopy (TEM), Fourier transforminfrared (FTIR) and thermo gravimetric analysis (TGA).The particle size of the produced ZnS lies in the range of 2.95±0.13–4.23±0.039 nm, depending on the milling period (1: 4 hrs), and in comparison to the Bohr radius of ZnS (2.5 nm).The TGA revealed stability of all products up to ~500oC, after which ZnS were found to react with O2 to produce ZnO as confirmed by XRD and FT-IR. The optical propertieswere studied by analyzing the recorded UV-Vis and photoluminescence (PL) spectra. The optical band gap of the assynthesized ZnS QDs lies in the range of 4.24–4.60 eV depending on the milling period. PL excitation peak shows a blue shift for ZnS-QDs obtained by milling. This blue shift could be attributed to a secondary effect of photo- corrosion process, which is in other words attributed as reduction in diameter of the ZnS QDs.