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ABSTRACT: A facile L-cysteine-assisted route was designed for the selectively controlled synthesis of 1D and novel, interesting 3D CdS spherical nanostructures constructed from CdS nanorods (or nanopolypods) in a binary solution. By controlling reaction conditions such as the molar ratio between Cd(OAc)2 and L-cysteine and the volume ratio of the mixed solvents, the synthesis of various 3D architectural structures and 1D wirelike structures in large quantities can be controlled. This is the first reported case of the direct growth of novel 3D self-assemblies of CdS nanorods (or nanopolypods). The morphology, structure, and phase composition of the as-prepared CdS products were examined by using various techniques (X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), high-resolution TEM, and Raman spectroscopy). On the basis of the results from TEM studies and our analysis, we speculate that in the present synthesis the L-cysteine dominates nucleation growth and the ethylenediamine (en)-dominated, oriented-assembly process. Interestingly, the products obtained show a gradient evolution in color from light-yellow to dark-yellow, which implies that their intrinsic optical properties change, possibly due to variations in their special morphologies and structures. This facile solution-phase L-cysteine-assisted method could be extended for the controlled preparation of other metal chalcogenides nanostructures with complex morphologies.
Chemistry 02/2007; 13(11):3076-81. · 5.93 Impact Factor
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ABSTRACT: Novel kelp-like crystalline β-SiC nanobelts have been synthesized through direct pyrolysis of methyltrichlorosilane at 600°C in an autoclave. The products are characterized by X-ray powder diffraction, field emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, electron diffraction, and Raman spectroscopy. On the basis of morphology and structural characterization, an apical growth mechanism is proposed to clarify the formation of as-prepared nanobelts. Also, at 420 nm, a broad peak is observed in the visible photoluminescence emission.
Journal of the American Ceramic Society 01/2007; 90(2):653 - 656. · 2.27 Impact Factor
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ABSTRACT: High yield hausmannite (Mn3O4) nanorods with diameters of about 100 nm and lengths up to 15–20 µm have been prepared by vacuum calcining of the precursor (Mn3O4+MnOOH), which was hydrothermally prepared by the reaction of PEG-20000 and KMnO4 at 180 °C for 20 h. Transmission electron microscopy and the selected-area electron diffraction pattern reveal that these Mn3O4 nanorods show single-crystal growth along the [100] direction. The PEG-20000 and the calcination conditions have key effects on the morphology and phase purity of the product. Magnetism measurements show that the blocking temperature for these Mn3O4 nanorods is 41 K, which agrees with the bulk material value, whereas the remnant magnetization and coercivity are 0.89 μB and 6177 Oe respectively.
Nanotechnology 09/2006; 17(19):4923. · 3.98 Impact Factor
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ABSTRACT: This paper reports well-aligned arrays of CuO nanoplatelets synthesized through a hydrothermal route without template's assistance. The surface of well-aligned arrays of CuO nanoplatelets looks like a wall. These nanoplatelets, possessing four clear edges, are 50-80 nm in thickness, 150-250 nm in width, and 0.8-1.5 microm in length. Electron microscopic detection shows that the nanoplatelet grows along the [010] direction. The Ostwald ripening mechanism has been used to describe the growth of CuO nanoplatelets. In addition, the optic and electrochemical properties of as-obtained products have been discussed. And the arrays of CuO nanoplatelets exhibit the blue shift in UV-visible spectra, a slow capacity fading rate, and a relatively high Coulombic efficiency in charge-discharge process.
The Journal of Physical Chemistry B 03/2006; 110(4):1632-7. · 3.70 Impact Factor
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ABSTRACT: Silicon carbide nanoflakes have been synthesized through a one-step solvothermal route involving reaction of SiCl4 and CaC2 at 180 °C for the first time. According to x-ray powder diffraction, infrared, and Raman spectra analysis, the obtained nanoflakes possess a crystalline structure of 2H–SiC. Electron microscopy investigations show that the nanoflakes have typical diameters of 200–500 nm, thickness of ∼ 15 nm, and grow along the [001] direction. The nanoflakes exhibit a new photoluminescence peak at ∼ 314 nm, which is ascribed to defects in the SiOx. The possible growth mechanism of the nanoflakes is discussed.
Applied Physics Letters 02/2006; 88(7):071913-071913-3. · 3.84 Impact Factor
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ABSTRACT: Fe3O4 novel fractal nanocrystals have been synthesized by a surfactant-assisted solvothermal process for the first time. X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Mössbauer spectroscopy (MS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) have been used to investigate the novel fractal nanocrystals. The lengths of the fractals are about 2-3 microm, and the trunks and branches of Fe3O4 fractals have almost the same diameters of ca. 30-50 nm. The roles of surfactant PEG-20000 and N2H4 have been discussed in detail. One key fact has been found that the ferrocene concentration has a vital effect on the morphologies of the products. The side-branching process and the oscillation of the concentration have been proposed to illustrate the formation mechanisms of the fractal nanocrystals. In addition, magnetic properties of Fe3O4 fractal nanocrystals have also been detected by a vibrating sample magnetometer, showing relatively high saturation magnetization (Ms) of ca. 78.75 emu/g.
The Journal of Physical Chemistry B 11/2005; 109(39):18356-60. · 3.70 Impact Factor
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ABSTRACT: Ultrathin magnetic Fe3O4 nanodiscs with thicknesses of ~20 nm and diameters ranging from 500 to 1000 nm have been obtained on a large scale by a surfactant-assisted solvothermal process. Transmission electron microscopy characterizations show that the nanodiscs grow along the [110] direction. NaOH and PEG-20000 (PEG stands for polyethylene glycol) have key effects on the morphology of the nanodiscs. In addition, the magnetic hysteresis loop of the ultrathin nanodiscs is obtained at room temperature.
Nanotechnology 06/2005; 16(9):1584. · 3.98 Impact Factor
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ABSTRACT: Single-crystalline alpha silicon–nitride nanowires have been achieved with large scale by the reaction of Mg3N2 and SiCl4 at 600 °C. Electron microscopy analyses have revealed that the nanowires have only ∼ 35 nm in diameter, up to 5 μm in length, and a preferred [001] growth direction. The nanowires exhibit the quantum size effect in optical properties, showing the redshift of an infrared band and the blueshift of the photoluminescence band. The growth mechanism of the nanowires have been properly discussed.
Applied Physics Letters 04/2005; 86(18):181901-181901-3. · 3.84 Impact Factor
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ABSTRACT: Flowerlike cupped-end ZnO microrod bundles have been hydrothermally synthesized from precursor ZnCl2(N2H4)2 in sheet shape at 140 degrees C for 12 h; under the same conditions using the same precursor in rod shape, uniform ZnO nanorods were obtained. XRD pattern indicated the sample is ZnO with hexagonal cell contants a = 3.251 A and c = 5.206 A. FE-SEM and TEM show the formation process of the ZnO sample. HRTEM revealed that the flowerlike cupped-end ZnO microrod bundles grow along the [101] axis. The UV emission peak at approximately 396 nm and the blue band emission peak at approximately 469 nm were observed by PL spectra. A possible formation mechanism was proposed.
The Journal of Physical Chemistry B 03/2005; 109(4):1361-3. · 3.70 Impact Factor
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ABSTRACT: ZnSe hollow nanospheres have been hydrothermally synthesized at 140 °C for 24 h starting from the precursor ZnCl2(N2H4)2 and Na2SeO3 by using hydrazine hydrate (N2H4H2O) as the reducing agent. The sample was characterized by XRD, ICP-AES, FE-SEM, and TEM. The BET surface area of the obtained ZnSe hollow nanospheres is 77.13 m2 g−1. Both the transverse optic (TO) and longitudinal optic (LO) phonon peaks in Raman spectra of the ZnSe product showed a obvious shift to lower frequency compared to bulk values; a blue-shift () was observed in PL spectra. It appears that the hollow spheres might be formed by a soft-template of gas bubbles of N2 produced during the reaction.
Nanotechnology 02/2005; 16(4):551. · 3.98 Impact Factor
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Berichte der deutschen chemischen Gesellschaft 09/2004; 2004(22):4521 - 4524. · 2.94 Impact Factor
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ABSTRACT: Carbon nanorods were produced with a yield of about 90% by the copyrolysis of C(6)H(6) and C(5)H(6) at 600 degrees C under the cocatalysis of Fe and Mg. Many novel Y-junction carbon nanorods were found in the products. The obtained carbon nanorods have a diameter in the range of 200-350 nm and are several micrometers in length. The effects of reactants, catalysts, and the temperature were investigated, and the experimental results indicate that C(5)H(6) and cocatalysts Fe and Mg play crucial roles in the formation of carbon nanorods. The possible formation mechanism of the carbon nanorods is discussed.
Inorganic Chemistry 09/2004; 43(17):5432-5. · 4.60 Impact Factor
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ABSTRACT: A facile route of large-scale synthesis of ZnTe nanorod bundles has been achieved by a solvothermal method in a mixed solvent of ethylenediamine and hydrazine hydrate and later thermal treatment combined. SEM images showed many nanorods stick together in the middle, composing a typical nanorod bundle. These nanorods have widths in the range 150–200 nm and lengths up to several micrometres. HRTEM and SAED demonstrated that the nanorods grow along [1 1 1] direction. Based on a series of contrast experiments under different reaction conditions, some probable effective factors were discussed.
Journal of Crystal Growth.
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ABSTRACT: Novel flower-like pattern of radially aligned ZnSe nanoflakes were synthesized via a facile solvothermal method in a mixed solvent of ethylenediamine and hydrazine hydrate. XRD, FESEM and TEM characterizations showed that as-prepared ZnSe sample is metastable wurtzite phase and the nanoflakes have uniform thickness of about 60 nm. The PL spectrum of the as-prepared sample was investigated. The formation conditions of the flower-like pattern of radially aligned ZnSe nanoflakes were discussed and it was found that the ratios of the solvent components are of great importance for the final formation of the flower-like structures.
Materials Chemistry and Physics 103:441-445. · 2.23 Impact Factor
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ABSTRACT: Single-crystalline α-MnO2 nanowires with diameters of 10–30 nm and lengths ranging from 6 to 10 μm have been successfully synthesized by hydrothermal treating a mixed solution of KMnO4 and NH4Cl at 140 °C for 24 h. The final products were characterized by XRD, FESEM, TEM and HRTEM. The effect of anion Cl− in the possible rolling formation mechanism was also briefly discussed.
Journal of Crystal Growth 279:415-419. · 1.73 Impact Factor
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ABSTRACT: ZnS hollow nanospheres have been hydrothermally synthesized at 200 °C for 4 h. In same condition ZnS microspheres were obtained when using acrylamide as the surfactant. XRD pattern indicates as-prepared sample is cubic ZnS with cell constant a = 5.391 Å and the average size of ZnS particles was 6.5 nm estimating from the Debye–Scherrer formula. TEM observed the hollow nanospheres have the diameters ranging from 200 to 300 nm with a shell thickness of about 40 nm. UV–vis and PL spectra recorded the optical properties of the sample, a blue-shift (∼19 nm) was observed. It appears that the hollow spheres might be formed by soft-template of gas bubbles of SO2 produced during the reaction.
Materials Chemistry and Physics.
