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1.
A chemical synthesis process for the fabrication of CdO nanowires is described. In the present work, transparent and conductive CdO films were synthesized on the glass substrate using chemical bath deposition (CBD) at room temperature. These films were annealed in air at 623 K and characterized for the structural, morphological, optical and electrical properties were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), optical and electrical resistivity. The XRD analysis showed that the as-deposited amorphous can be converted in to polycrystalline after annealing. Annealed CdO nanowires are 60-65 nm in diameter and length ranges typically from 2.5 to 3 μm. The optical properties revealed the presence of direct and indirect band gaps with energies 2.42 and 2.04 eV, respectively. Electrical resistivity measurement showed semiconducting behavior and thermoemf measurement showed n-type electrical conductivity.  相似文献   

2.
Well-defined flower-like Cd(OH)2 microstructures have been successfully synthesized via a simple aqueous solution route, using CdCl2 and NaOH as the reactants, and triethanolamine (TEA) as the modifying agent. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-vis spectrometer were used to characterize the products. SEM and TEM images illustrated that the flower-like Cd(OH)2 bundles consisted of hexagonal nanoplates with thickness of about 50 nm. The adsorption of TEA on (0 0 1) plane of the growing Cd(OH)2 crystal leads to the flower petals in appearance. Further experiments evidenced that the positively charged Cd(OH)2 could effectively adsorb or separate the negatively charged dye molecules.  相似文献   

3.
Room temperature soft chemical deposition route has been utilized to grow thin films of ZnO on glass substrate. Annealing at 673 K removed zinc hydroxide phase and nanofibrous ZnO films with wurtzite crystal structure were obtained. Decrease in the room temperature electrical resistivity from 107 to 104 Ω cm was observed after annealing. The nanofibrous ZnO thin films were sensitive to the explosive liquefied petroleum gas (LPG) and the maximum response of 17% at 698 K under the exposure of 6500 ppm of LPG was obtained.  相似文献   

4.
5.
Tube brush-like ZnO nanostructures were synthesized by a simple chemical vapor deposition method with Zn and ZnO as precursors. These special ZnO nanostructures were characterized by Scanning Electron Microscope, Energy Dispersive X-ray Spectroscopy, High Resolution Transmission Electron Microscope and Cathodoluminescence (CL) techniques. Empty backbones or comb ribbons backbones were found inside the tube brush-like ZnO structures and fuzzy ZnO nanowires outside. Outside ZnO nanowires grow along the c axis and show green CL emission. The growth mechanism of the hierarchical ZnO nanostructures was investigated by a series of experiments at different growth temperatures and different duration times, and a secondary growth mechanism has been proposed and discussed.  相似文献   

6.
Solution synthesis of ZnO nanotubes via a template-free hydrothermal route   总被引:1,自引:0,他引:1  
ZnO nanotubes were successfully synthesized by a simple template-free hydrothermal method. X-ray powder diffraction and transmission electron microscopy were used to characterize the as-prepared ZnO nanotubes. The average size of the nanotubes is 200-500 nm in length and 20-30 nm in diameter. In addition, a further investigation of the optimized synthetic conditions has been carried out.  相似文献   

7.
Single-crystalline zinc oxide (ZnO) nanowires were synthesized from zinc powder and H2O through a simple chemical route at 730 °C in Ar atmosphere. The potential exists for bulk synthesis of ZnO nanowires at temperatures significantly less than the 200–300 °C of thermal evaporation methods reported formerly. Scanning electron microscopy and transmission electron microscopy observations reveal that the ZnO nanowires are structurally uniform, have lengths up to several hundreds of micrometers and diameters of about 40–60 nm and crystallize in a hexagonal structure. The growth of ZnO nanowires is controlled by the vapor–solid crystal-growth mechanism. Photoluminescence measurements show that the ZnO nanowires have a strong near-band ultraviolet emission at 380 nm and a green light emission at 520 nm caused by oxygen vacancies. PACS 81.05.Ys; 78.55.Et  相似文献   

8.
Zinc Sulfide (ZnS) nanowires were grown in the pores of anodic alumina membrane. A simple chemical reaction technique was used where pores in the anodic alumina membrane act as reactors. Uniform morphology of nanowires was found using scanning electron microscopy (SEM). X-ray diffraction (XRD) and Micro-Raman spectroscopy revealed the wurtzite nature of ZnS nanowires. UV–visible spectroscopy of nanowires exhibited no blue shift. The room temperature photoluminescence measurement observed an emission peak around 390 nm.  相似文献   

9.
Highly uniform three-dimensional dendrite-like CeO2 crystallites were successfully prepared in large quantities with a thermal decomposition of precursor approach applied. The precursor with an average size of 10 μm was prepared in an aqueous solution containing Ce(NO3)3·6H2O, CO(NH2)2 and ammonia at 160 °C with no additional phase. The influence of ammonia on the dendrites formation was discussed. The dendritic pattern of precursor almost remained in the as-prepared product. The optical absorption spectrum indicates that CeO2 dendrites have a direct band gap of 3.52 eV.  相似文献   

10.
S. Deabate  F. Fourgeot  F. Henn 《Ionics》1999,5(5-6):371-384
Both structural and electrochemical properties of non-doped nickel hydroxide produced by a new synthesis route of electrodialysis are investigated. A comparison with two spherical β-type Ni(OH)2 is made. Structural characterization is carried out by X-ray diffraction, vibrational spectroscopy and thermal analysis. Electrochemical properties are studied by cyclic voltammetric and chronoamperometric experiments. The material obtained by electrodialysis is found to have a highly defective structure, which corresponds to a complex electrochemical behavior. More particlarly, it is shown that this new nickel hydroxide is more stable regarding the β → γ transformation. Project financed by the E.U. under the Brite Euram program (#BRPR-CT97-0515) Paper presented at the 6th Euroconference on Solid State Ionics, Sept. 12–19, 1999, Cetraro, Calabria, Italy  相似文献   

11.
Cadmium hydroxide (Cd(OH)2) and cadmium oxide (CdO) nano and micro crystals were synthesized in ethanol-water medium using cadmium foil both as a source and substrate under solvothermal condition. Different concentrations of ammonium hydroxide, hydrazine hydrate, sodium hydroxide and potassium hydroxide were added to study the structural and morphological variations in the products. Synthesis was carried out at different temperatures to study the growth stages of the nano/microstructures. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The as-prepared Cd(OH)2 products were transformed to CdO by thermal treatment in air. The possible growth mechanism for the formation of different morphologies at different basic medium has been proposed. The optical absorption measurement was carried out to determine the values of the band gap of CdO.  相似文献   

12.
13.
An easy method for the preparation of trigonal selenium nanowires at room temperature was developed. The influence of the environmental temperature on the growth rate and morphology was discussed as an important factor. And the illumination could badly foreclose the shaping of the one-dimensional morphology. Ethylenediamine was selected as solvent to prepare the precursor, amorphous selenium. SEM analyses of the phase-transitional processes at different stages showed the integrated transformation of morphology. As a result, nanowires with uniform diameter of about 45 nm were obtained, which was also confirmed by TEM investigations. SAED and XRD pattern demonstrated the as-synthesized nanowires were single-crystalline and trigonal phase. PACS 81.05.Cy; 81.07.Vb; 81.10.Jt; 81.16.Be; 81.16.Dn  相似文献   

14.
In this study, the CdS nanocrystalline thin films obtained from an ammonia-free chemical bath deposition process. The crystallites with a size range of 10–20 nm in diameter with zinc blend (cubic) and wurtzite (hexagonal) crystal structure and strong photoluminescence were prepared from the mixture solutions of: cadmium chloride dihydrate as a cadmium source, thiourea as a sulfur source and sodium citrate dihydrate as a complexing agent for cadmium ions. The well-cleaned glass used as a substrate for thin films deposition. The obtained samples were characterized by the techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), atomic force microscopy (AFM) and fluorescence spectroscopy. Also, the effect of two parameters such as pH and temperature of reaction on the synthesis of CdS nanocrystals was studied. Finally, it was found the CdS nanocrystals showed sharp excitation features and strong “band-edge” emission.  相似文献   

15.
Room temperature chemical synthesis of PbSe thin films was carried out from aqueous ammoniacal solution using Pb(CH3COO)2 as Pb2+ and Na2SeSO3 as Se2− ion sources. The films were characterized by a various techniques including, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), Fast Fourier transform (FFT) and UV-vis-NIR techniques. The study revealed that the PbSe thin film consists of preferentially oriented nanocubes with energy band gap of 0.5 eV.  相似文献   

16.
Novel $N$ -alkyl-2-(alkylthio)-1 $H$ -imidazole derivatives were synthesized in a single step by an efficient and simple method in high yields. Readily available starting materials, mild reaction conditions, operational simplicity and novelty are the key advantages of this method. Besides their novel structures, these compounds may have important biological activities and industrial applications.  相似文献   

17.
La(OH)3/Ni(OH)2 nanocables and La(OH)3 nanorods were synthesized by the reaction of KOH with La(NO3)3 and Ni(NO3)2 at 180 °C under a hydrothermal conditions. X-ray diffraction, transmission electron microscopy and thermal analyses indicated that the nanocable consists of La(OH)3 core and Ni(OH)2 outer shell. The diameters of the La(OH)3 nanorods range from 20 to 30 nm and the lengths range from 150 to 1000 nm. The thickness of the Ni(OH)2 coating ranges from 10 to 20 nm. The formation mechanism of the nanocables is discussed.  相似文献   

18.
Zinc sulphide (ZnS) thin films are deposited using chemical bath deposition method on the glass substrates in an aqueous alkaline reaction bath of zinc acetate and thiourea along with non-toxic complexing agent tri-sodium citrate at 95 °C. The results show noteworthy improvement in the growth rate of the deposited ZnS thin films and thickness of the film increases with the deposition time. From X-ray diffraction patterns, it is found that the ZnS thin films exhibit hexagonal polycrystalline phase reflecting from (101) and (0016) planes. The high resolution transmission electron microscopy studies confirmed the formation of hexagonal phase from the d-value calculation which was 0.3108 nm. X-ray photoelectron spectroscopy reveals that the Zn–S bonding energy is at 1022.5 and 162.1 eV for Zn 2p3/2 and S 2p1/2 states, respectively. Field emission scanning electron microscopy study shows that deposited thin films are highly uniform, with thin thickness and completely free from large ZnS clusters which usually form in aqueous solutions. Atomic force microscopy investigates that root mean square values of the ZnS thin films are from 3 to 4.5 nm and all the films are morphologically smooth. Energy dispersive spectroscopy shows that the ZnS thin films are relatively stoichiometric having Zn:S atomic ratio of 55:45. It is shown by ultraviolet–visible spectroscopy that ~90% transmittance and ~10% absorbance for the ZnS films in the visible region, which is significantly higher than that reported elsewhere and the band gap energy of the ZnS films is found to be 3.76, 3.74, and 3.71 eV, respectively.  相似文献   

19.
The direct polyol method is used to prepare copper aluminium sulfide CuAlS2 nanowires. The lattice constants of CuAlS2 nanowires calculated from powder X-ray diffraction data indicates chalcopyrite structure. The CuAlS2 nanowires are uniformly in shape and their dimensions are about 50 nm in diameter and several of micrometers in length. The Photoluminescence (PL) spectrum of CuAlS2 nanowires show a sharp absorption edge at 358.96 nm and a strong near band edge emission at 3.46 eV. The direct energy gap Eg of the sample has been calculated as 3.48 eV, that corresponding to the photoluminescence study. A possible formation mechanism of copper aluminium sulfide is proposed.  相似文献   

20.
TaC nanowires are expected to be an ideal reinforcing material in ultra-high-temperature ceramics. However, their growth mechanisms and mechanical properties remain unclear, and low-cost large-scale synthesis has not been realised. In this study,bulk synthesis of [100]-oriented TaC nanowires is accomplished by carbothermal synthesis through a direct vapor-solid mechanism. Thermal resonance test results show that the synthesized square TaC nanowires with cross-sectional side-lengths of 65 to 497 nm have a size-independent Young's modulus of(510.6±12.6) GPa; very close to the corresponding values of their bulk counterparts, but differing considerably from previously published measurements. Molecular dynamics(MD) simulations show that TaC nanowires with side-lengths of above 15 nm have a constant Young's modulus of 517 GPa, and size effects on the modulus values should only occur at side-lengths below 15 nm. During bending tests, the TaC nanowires fracture into several segments in a brittle mode, and exhibit an increasing fracture strain from 1.88% to 4.28% as their side-length decreases from 489 to 90 nm. Weibull statistics analyses and TEM observations indicate that the failure of the nanowires should be primarily dependent on the number and size of surface defects. MD simulations further reveal that the defect-free TaC nanowires fail brittlely at a theoretical strain up to 5.76%.  相似文献   

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