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- 2021| Nature ResearchWe report a simple, economical and low temperature route for phase-pure synthesis of two distinct phases of Cu–Sb–S, chalcostibite (CuSbS2) and tetrahedrite (Cu12Sb4S13) nanostructures. Both compounds were prepared by the decomposition of a mixture of bis(O-ethylxanthato)copper(II) and tris(O-ethylxanthato)antimony(III), without the use of solvent or capping ligands. By tuning the molar ratio of copper and antimony xanthates, single-phases of either chalcostibite or tetrahedrite were obtained. The tetrahedrite phase exists in a cubic structure, where the Cu and Sb atoms are present in different coordination environments, and tuning of band gap energy was investigated by the incorporation of multivalent cationic dopants, i.e. by the formation of Zn-doped tetrahedrites Cu12−xZnxSb4S13 (x = 0.25, 0.5, 0.75, 1, 1.2 and 1.5) and the Bi-doped tetrahedrites Cu12Sb4−xBixS13 (x = 0.08, 0.15, 0.25, 0.32, 0.4 and 0.5). Powder X-ray diffraction (p-XRD) confirms single-phase of cubic tetrahedrite structures for both of the doped series. The only exception was for Cu12Sb4−xBixS13 with x = 0.5, which showed a secondary phase, implying that this value is above the solubility limit of Bi in Cu12Sb4S13 (12%). A linear increase in the lattice parameter a in both Zn- and Bi-doped tetrahedrite samples was observed with increasing dopant concentration. The estimated elemental compositions from EDX data are in line with the stoichiometric ratio expected for the compounds formed. The morphologies of samples were investigated using SEM and TEM, revealing the formation of smaller particle sizes upon incorporation of Zn. Incorporation of Zn or Bi into Cu12Sb4S13 led to an increase in band gap energy. The estimated band gap energies of Cu12−xZnxSb4S13 films ranges from 1.49 to 1.6 eV, while the band gaps of Cu12Sb4−xBixS13 films increases from 1.49 to 1.72 eV with increasing x.
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- Copper sulfide thin films and nanoparticles have been prepared via aerosol assisted chemical vapour deposition and solvothermal hot injection routes, respectively. Both routes employed heterocyclic amine based benzoylthioureato-copper(II) complexes as single source precursors. Copper sulfide thin films of diverse morphologies ranging from cubic to snowy or irregular crystallites depending on the deposition temperature were observed. Powder X-ray diffraction studies of the as deposited thin films have indicated the formation of hexagonal and cubic phases of copper sulfide. In the case of the nanoparticles, Roxbyite (Cu1.75S) phase was obtained in dodecanethiol at temperatures of 150, 190 and 230 °C. However, a preferred growth of nanoparticles was observed in the presence of oleylamine whereas the roxbyite phase was obtained at temperatures of 150, 200 and 250 °C. Also transmission electron microscopy showed the formation of close to spherical, hexagonal nano-disk and rod shaped nanoparticles.
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- 2019| Springer NatureLead alkyl xanthate (alkyl = octyl, nonyl and dodecyl) complexes have been synthesized and characterized using micro-elemental analyses, infra-red and thermogravimetric analyses. The synthesized complexes were used as molecular precursors (SSP) for preparation of PbS nanowires using the hot injection technique in olive oil. The influence of the alkyl chain length on the structural and electronic properties on the PbS nanowires are reported. Powder X-ray diffraction (p-XRD) analyses of the as-synthesized nanowires show a face centred cubic rocksalt structure (halite). Transmission electron microscope (TEM) images of the as-synthesized PbS nanomaterials reveal 1-dimensional growth of nanowires. The estimated optical band gaps from the Tauc plots were 1.34, 1.41 and 1.45 eV for PbS nanowires obtained from the octyl, nonyl and dodecyl chain lengths respectively at 125 °C. The composition and purity of the as-synthesized PbS nanowires was observed by energy dispersive X-ray analysis (EDX) which showed an approximately 1:1 Pb to S ratios in all the as-synthesized nanowires.
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- A series of Fe(III), Co(III), Ni(II), Cu(II), Zn(II) and In(III) N-morpholine-N'-benzoyl thiourea complexes have been synthesized and characterized by elemental analysis, thermal analysis, infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy and single-crystal X-ray crystallography. Thermogravimetric analysis shows that all the complexes undergo a two-step decomposition process except for the iron(III) complex and the indium(III) complexes, which show three-step and one-step decompositions, respectively. The complexes are thermally stable up to approximately 300°C. The ligand coordinates the various metal ions in a bidentate (L-kO,S) chelating mode, facilitated by deprotonation of the acidic amide (–C(O) N'HC (S)) moiety. This mode of coordination allows for the facile formation of neutral bis/tris-6-membered chelates of type [M(L-kS,O)x] where x = 2 or 3 for divalent or trivalent metal ions, respectively.
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