The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Neerish Revaprasadu - One of the best experts on this subject based on the ideXlab platform.
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A simple route to shape controlled CdS nanoparticles
Journal of Physics and Chemistry of Solids, 2013Co-Authors: Ayorinde O. Nejo, Rajasekhar V.s.r. Pullabhotla, Neerish RevaprasaduAbstract:Abstract We report the synthesis of CdS nanoparticles in the form of spheres, triangles and wire-like structures. The method involves the reaction of reduced sulfur with a Cadmium Salt followed by thermolysis in hexadecylamine (HDA). The different shapes were obtained by variation of reaction conditions such as reaction time, temperature and Cadmium source. The optical studies show the particles to be quantum confined and luminescent at room temperature.
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Facile synthesis of organically capped CdTe nanoparticles.
Journal of nanoscience and nanotechnology, 2012Co-Authors: Nhlakanipho Mntungwa, Viswanadha Srirama Rajasekhar Pullabhotla, Neerish RevaprasaduAbstract:A simple method for the preparation of tri-n-octylphosphine oxide (TOPO) and hexadecylamine (HDA) capped CdTe particles have been employed in this study. The method involves the reduction of tellurium in water followed by the addition of the Cadmium Salt and thermolysis in TOPO and HDA. The influence of the reduction time (2, 4 and 6 h) of tellurium on the optical properties was investigated. The particles were characterised by electron microscopy and X-ray diffraction techniques.
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A facile route to shape controlled CdTe nanoparticles
Materials Chemistry and Physics, 2011Co-Authors: Nhlakanipho Mntungwa, Pullabhotla V.s.r. Rajasekhar, Neerish RevaprasaduAbstract:Abstract Hexadecylamine (HDA) capped CdTe nanoparticles have been synthesized using a facile hybrid solution based/thermolysis route. This method involves the reaction by the addition of an aqueous suspension or solution of a Cadmium Salt (chloride, acetate, nitrate or carbonate) to a freshly prepared NaHTe solution. The isolated CdTe was then dispersed in tri-octylphosphine (TOP) and injected into pre-heated HDA at temperatures of 190, 230 and 270 °C for 2 h. The particle growth and size distribution of the CdTe particles synthesized using Cadmium chloride as the Cadmium source were monitored using absorption and photoluminescence spectroscopy. The final morphology of the CdTe nanoparticles synthesized from the various Cadmium sources was studied by transmission electron microscopy (TEM) and high resolution TEM. The Cadmium source has an influence on the final morphology of the particles.
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A new synthetic route to organically capped Cadmium selenide nanoparticles
New Journal of Chemistry, 2008Co-Authors: Oluwatobi Samuel Oluwafemi, Neerish RevaprasaduAbstract:We report a novel method for the preparation of monodispersed hexadecylamine (HDA) and tri-n-octylphosphine oxide (TOPO) capped CdSe nanoparticles. This route involves the reaction of selenium powder with sodium borohydride (NaBH4) to produce selenide ions, followed by the addition of a Cadmium Salt. The nanoparticles showed quantum confinement with characteristic close to band-edge luminescence in their emission spectra. The nanoparticles were characterised by optical spectroscopy, infrared (IR) spectroscopy, X-ray diffraction (XRD), transmission electron spectroscopy (TEM), and energy dispersive spectroscopy (EDS).
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A novel one-pot route for the synthesis of water-soluble Cadmium selenide nanoparticles
Journal of Crystal Growth, 2008Co-Authors: S.o. Oluwafemi, Neerish Revaprasadu, Antonio J. RamirezAbstract:Abstract A novel, facile one-pot synthetic route to highly water dispersible and potentially biocompatible CdSe nanoparticles is reported. The monodispersed CdSe particles are passivated by cysteine, with water being the solvent. This route involves the reaction of selenium powder with sodium borohydride to produce selenide ions, followed by the addition of a Cadmium Salt and l -cysteine ethyl ester hydrochloride. The nanoparticles formed show quantum confinement fluorescing in the blue region. Fourier transform infrared spectroscopy study shows that CdSe nanoparticles are capped through mercapto group of the amino acid cysteine whilst its free amino and carboxylate groups make it amenable to bioconjugation establishing the possibility of using these as fluorescent biomarkers. High-resolution transmission electron spectroscopy images of these materials show well-defined, crystalline nanosized particles. Energy dispersive spectroscopy spectra confirm the presence of the corresponding elements.
P.j. Sebastian - One of the best experts on this subject based on the ideXlab platform.
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Preparation and characterization of semiconducting Zn1−xCdxSe thin films
Solar Energy Materials and Solar Cells, 2004Co-Authors: Rathinam Chandramohan, Thaiyan Mahalingam, Jinn P. Chu, P.j. SebastianAbstract:Abstract The electrodeposition of Zn 1− x Cd x Se polycrystalline semiconducting thin films from aqueous acidic bath without any additives onto tin oxide-coated conducting glass and titanium substrates are described. The influence of deposition parameters on the film formation and deposition mechanism based on cyclic voltammetry is discussed. X-ray diffraction studies showed the polycrystalline wurtzite nature for all the films deposited under the proposed conditions. The optical studies revealed the band gap values in the range between 2.82 and 1.72 eV as the film composition changes from ZnSe to CdSe. It has been observed that the concentration of Cadmium Salt plays an essential role on the alloy formation. The surface morphological studies and composition analysis were carried out and the results are discussed.
Youqi Tang - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and X-ray crystal structure of hexakis(μ-(p-tert-butylthiophenolato))-mono(p-tert-butylthiophenolato) trichloro-tetracadmate(II) dianion
Polyhedron, 1994Co-Authors: Kaluo Tang, Tianbing Xia, Xianglin Jin, Youqi TangAbstract:Abstract A tetranuclear chlorine-containing cage thiolate cluster complex of Cadmium, [HNEt3]2[Cd4(μ-SC6H4But-4)6(SC6H4But-4)Cl3], consisting of a Cd4(μ-S)6 adamantane-like cage, was synthesized directly from the reaction of a Cadmium Salt and corresponding thiolate. The chloride ions, introduced unexpectedly, act as terminal ligands.
Kazuhiko Seki - One of the best experts on this subject based on the ideXlab platform.
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Formation of the Newly Greenish Organized Molecular Film of Long-Chain Diynoic Acid Derivatives by Photopolymerization and Its Structural Study Using Near-Edge X-ray Absorption Fine Structure (NEXAFS) Spectroscopy
The Journal of Physical Chemistry B, 2004Co-Authors: Atsuhiro Fujimori, Mikako Ishitsuka, Hiroo Nakahara, Eisuke Ito, Masahiko Hara, Kaname Kanai, Yukio Ouchi, Kazuhiko SekiAbstract:The effect of molecular arrangements with annealing on photopolymerization in the Langmuir−Blodgett films of 10,12-pentacosadiynoic acid Cadmium Salt was investigated using UV−vis spectroscopy, out-of plane and in-plane X-ray diffraction (XRD), and polarized near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The formation of a greenish polymer film with an extended conjugate system was determined to be related to the film structures. Furthermore, the incident-angle dependence of C1s−π* transition peaks on the annealed transferred film with an extended conjugate system was confirmed by C K-edge polarized NEXAFS spectroscopy, whereas this dependency was not observed on nonannealed multilayer films. In addition, multilayers of metal-free 10,12-pentacosadiynic acid were examined by photopolymerization, and their film structures were elucidated. Contrary to expectations, a red-colored polymer film was observed to form highly ordered side-chain orientations with the shift of the C1s−π* transition ...
J Herrero - One of the best experts on this subject based on the ideXlab platform.
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accurate control of thin film cds growth process by adjusting the chemical bath deposition parameters
Thin Solid Films, 1998Co-Authors: C Guillen, M A Martinez, J HerreroAbstract:The influence of Cadmium Salt and thiourea concentrations and deposition time on the optical and electrical properties of chemical bath deposited CdS thin films has been studied. The decrease in Cadmium Salt and increase in thiourea concentrations, to the order of 1 mM and 100 mM respectively, have been found to be optimal for raising the optical transmission without conductivity deterioration and allowing a suitable thickness control less dependent on the deposition time. Additionally, 200 and 400°C air-annealing treatments for 20 min have been carried out. Their analysis has demonstrated the optical absorption edge shifts towards lower photon energies as the air-annealing temperature raises. Besides, dark and light resistivities decrease in comparison with as-grown CdS data.
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Morphological and structural studies of CBD-CdS thin films by microscopy and diffraction techniques
Applied Surface Science, 1998Co-Authors: M A Martinez, C Guillen, J HerreroAbstract:Abstract The influence of Cadmium Salt and thiourea concentrations on the morphological and structural properties of chemical bath-deposited CdS thin films has been investigated. Two different feature regimes have been distinguished: an inner continuous layer grown directly on the glass and independent on the deposition conditions, and other porous overlayer, more dependent on the chemical concentrations. Root mean square, RMS, and average roughnesses, Ra, as quantified by AFM, are about 10–13 nm and 7–11 nm, respectively, for all CdS samples tested. These films are sulphur-poor, decreasing S/Cd atomic ratio from 0.82 at low Cadmium Salt, 1 mM, and high thiourea concentrations, 100 mM, down to 0.76 at higher [Cd2+], 5 mM, and lower [TU], 10 mM.
