Magnetizace jako efektivní nástroj pro kinetickou evaluaci mechanochemické syntézy chalkopyritu CuFeS2

Copper, iron, and sulphur in elemental form were applied for mechanochemical synthesis of chalcopyrite CuFeS2. Products of synthesis were characterized by XRD method and evaluated by Rietveld analysis. A mixture of cubic (JCPDS 75-6866) and tetragonal (JCPDS 37-0471) phases of chalcopyrite with almost identical diffractograms were identified. Both phases are nanocrystalline with sizes 13 nm and 7 nm for laboratory and industrial milling, respectively. For determination of iron consumption during the synthesis, method of magnetometry has been applied. Based on magnetization data reflecting time dependent incorporation of elemental iron into chalcopyrite nanostructure, the kinetics of the synthesis was evaluated. From kinetic data the rate constant of reaction k, as well as the conversion degree R were determined. High conversion degree of mechanochemical synthesis performed in a laboratory mill (R = 100%), as well as in an industrial mill (R = 96%) offer the possibility to scale-up the process of synthesis in preparation of this perspective magnetic semiconductor. The method of magnetometry was proved to be an effective tool for following the processes of synthesis where iron particles are incorporated.Měď, železo a síra v elementární formě byly použity pro mechanochemickou syntézu chalkopyritu CuFeS2. Produkty syntézy byly charakterizovány metodou XRD a hodnoceny analýzou společnosti Rietveld. Byla zjištěna směs krychlových (JCPDS 75-6866) a tetragonálních (JCPDS 37-0471) fází chalkopyritu s téměř totožnými difraktogramy. Obě fáze jsou nanokrystalické s velikostí 13 nm pro laboratorní a 7 nm pro průmyslové mletí. Pro stanovení spotřeby železa během syntézy byla použita metoda magnetometrie. Na základě magnetizačních dat odrážejících na čase závislou inkorporaci elementárního železa do chalkopyritové nanostruktury byla vyhodnocena kinetika syntézy. Z kinetických údajů byla stanovena rychlostní konstanta reakce k a také konverzní stupeň R. Vysoký stupeň konverze mechanochemické syntézy prováděné v laboratorní válcovně (R = 100 %), jakož i v průmyslové válcovně (R = 96 %) nabízí možnost rozšířit proces syntézy při přípravě tohoto perspektivního magnetického polovodiče. Ukázalo se, že metoda magnetometrie je účinným nástrojem pro sledování procesů syntézy, při nichž jsou obsaženy částice železa

Mechanochemistry of Chitosan-Coated Zinc Sulfide (ZnS) Nanocrystals for Bio-imaging Applications

Abstract The ZnS nanocrystals were prepared in chitosan solution (0.1 wt.%) using a wet ultra-fine milling. The obtained suspension was stable and reached high value of zeta potential (+57 mV). The changes in FTIR spectrum confirmed the successful surface coating of ZnS nanoparticles by chitosan. The prepared ZnS nanocrystals possessed interesting optical properties verified in vitro. Four cancer cells were selected (CaCo-2, HCT116, HeLa, and MCF-7), and after their treatment with the nanosuspension, the distribution of ZnS in the cells was studied using a fluorescence microscope. The particles were clearly seen; they passed through the cell membrane and accumulated in cytosol. The biological activity of the cells was not influenced by nanoparticles, they did not cause cell death, and only the granularity of cells was increased as a consequence of cellular uptake. These results confirm the potential of ZnS nanocrystals using in bio-imaging applications