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- 저자 : M. Taherian (검색결과 2 건)
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M. Taherian,A.A. Sabbagh Alvani,M. A. Shokrgozar,R. Salimi,S. Moosakhani,H. Sameie,F. Tabatabaee 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.2
In the present study, the ZnS semiconductor quantum dots were successfully synthesized via an aqueous method utilizing glutathione (GSH), thioglycolic acid (TGA) and polyvinyl pyrrolidone (PVP) as capping agents. The structural, morphological and photo-physical properties and biocompatibility were investigated using comprehensive characterization techniques such as x-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), dynamic light scattering (DLS), Fourier transform infrared spectrometry (FT-IR), UVVis optical absorption, photoluminescence (PL) spectrometer and MTT assay. The XRD patterns showed a cubic zinc blende crystal structure and a crystallite size of about 2 - 3 nm using Scherrer’s equation confirmed by the electron micrographs and Effective Mass Approximation (EMA). The DLS and zeta-potential results revealed that GSH capped ZnS nanoparticles have the narrowest size distribution with an average size of 27 nm and relatively good colloidal stability. Also, the FT-IR spectrum confirmed the interaction of the capping agent groups with ZnS nanoparticles. According to the UV-Vis absorption results, optical bandgap of the spherical capped nanoparticles is higher compared to the uncapped sample and could be wider than 3.67 eV (corresponding to the bulk ZnS), which is due to the quantum confinement effect. From photoluminescence spectra, it was found that the emission becomes more intensive and shifts towards the shorter wavelengths in the presence of the capping agent. Moreover, the emission mechanism of uncapped and capped ZnS was discussed in detail. Finally, the MTT results revealed the satisfactory (>94%) biocompatibility of GSH capped ZnS quantum dots which would be a promising candidate applicable in fluorescent biological labels.
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F. Tabatabaee,A.A. Sabbagh Alvani,H. Sameie,S. Moosakhani,R. Salimi,M. Taherian 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.1
The most effective process parameters were determined to synthesize spherical LaF3 nanoparticles with controlla-ble size based on ethylenediaminetetraacetic acid (EDTA) via co-precipitation technique. Thermogravimetric-differential thermal analysis, X-ray diffraction, scanning electron microscopy, dynamic light scattering and FT-IRspectroscopy were used to characterize the resulting powders. Detailed investigations revealed that the optimalLaF3 host nano-material was obtained when NH4F was used as a fluoride source in the presence of EDTAat pH = 5. Furthermore, photoluminescence spectra showed an intense double emission peak at 289 and 302nm for cerium-doped LaF3 nanocrystals excited at 253 nm, which was assigned to the well-known 5d→4f(2F5/2 and2F7/2) transitions of Ce3+levels due to luminescence center mechanism. The experimental resultsindicate that the synthesized LaF3:0.05Ce powders with a band gap of 5.3 eV are promising phosphors for highdensity scintillators.
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