Chemistry

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Browsing Chemistry by Subject "CdS Nanorods and PbS Nanoparticles"

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    Cadmium and lead thiosemicarbazide complexes : precursors for the synthesis of CdS nanorods and PbS nanoparticles
    (2005) Mlondo, Sibusiso Nkosikhona; Revaprasadu, N.
    This work reports the shape controlled synthesis of metal sulfide nanomaterials with varying morphologies using single source precursors based on the thiosemicarbazide ligand. The single crystal X-ray structures of [Cd(NH2CSNHNH2)CI2]n, [Cd(NH2CSNHNH2)2Cl2]n and [Pb(NH2CSNHNH2 )(N03)2] precursor complexes are reported and discussed. The non crystalline analogue of the cadmium complexes, [Cd(NH2CSNHNH2)2Cl2] was also synthesized and principally used to determine the effect of the precursor concentration and the growth temperature on the growth and final morphology of the CdS nanoparticles. The precursors were thermolysed in a hot co-ordinating solvent such as hexadecylamine (HDA) for CdS and tri-w-octylphosphine (TOPO) for PbS, using the "one-pot" single-molecule precursor route. The shape was found to move from short rods and dots to long rods at higher temperatures, where the growth is not easy to control. By contrast, at moderate temperatures the shape evolution was the opposite with the precursor concentration being the variation, as we moved from higher to lower concentrations. On the temperature variable's front, higher temperatures were found to favour the formation of shorter rods and dots whereas lower temperatures favour longer rods. By varying the important parameters such as precursor concentration and reaction temperature, various nanomaterials with a range of morphologies and sizes could be prepared. The effect of the nature of the precursor was also varied by synthesising nanoparticles from different crystalline complexes of the same metal (cadmium) and ligand (thiosemicarbazide) as precursors, which were found to give the nanoparticles of different crystallinity and aspect ratios. [Pb(NH2CSNHNH2 )(N03)2] was also used to synthesize PbS nanoparticles, in which determination shape control could not in be achieved. UV/Vis and photoluminescence spectra were used to study the materials optical properties of the material. The structural properties of the materials were studied by X-ray diffraction and TEM instruments.
University of Zululand