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Wanbang Xu Yongxian Wang Ronghui Xu Sheng Liang Guoxin Zhang Duanzhi Yin 《Journal of Materials Science》2007,42(16):6942-6945
An optimized synthesis route was applied for control the preparation of CdS nanocrystals (NCs) in an aqueous solution. Some
key factors which influencing the characters of CdS NCs, such as stabilizers, ratio of reactant etc, were investigated. It
was found that the fluorescence (FL) intensity of CdS NCs could be dramatically enhanced by refluxing. The size, shape, crystal
structure and the optical properties of CdS NCs were also characterized by TEM, XRD, UV–Vis and FL spectra. The result showed
that the well-disperse spheres CdS NCs with 6 nm in diameter were obtained. 相似文献
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功能化CdS纳米晶的合成及CdS/聚苯乙烯纳米杂化材料的研究 总被引:3,自引:0,他引:3
以氯化镉和硫化钠为原料,采用巯基乙醇为有机配体,在H2O/DMF的溶剂中,制得分散均匀且表面富含羟基基团CdS纳米晶溶液.我们使用γ-甲基丙烯氧丙基三甲氧基硅烷(MPS)来修饰CdS纳米晶的表面,得到双键官能团化的CdS纳米晶.通过原位自由基聚合方法,成功地得到了聚苯乙烯基CdS纳米晶复合材料.利用傅里叶红外光谱仪(FT-IR)、透射电子显微镜(TEM)、紫外-可见光吸收光谱仪(UV-vis)、X射线衍射分析仪(XRD)、热重分析仪(TGA)、荧光光谱 (PL) 考察了CdS纳米晶及CdS/聚苯乙烯复合材料的结构和光学性能的关系规律.结果表明巯基乙醇表现出良好的光学性能,其配体不是简单的物理吸附于纳米晶表面,而是以化学键的形式和纳米晶表面镉原子相结合.相比于纯的聚苯乙烯材料,聚苯乙烯基CdS纳米晶材料表现出良好的光学和热学性能. 相似文献
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以醋酸镉和硫为原料,采用二硫化四乙基秋兰姆TETD和2,2-二硫代二苯并噻唑为成核剂,利用无水无氧系统在ODE的溶液中制备了尺寸可控、单分散、均一的半导体CdS纳米材料.采用XRD、粒度分析、SEM技术分别表征产物的结构、粒度和形貌.通过改变两种成核剂的使用量及反应时间可以得到不同粒径的CdS纳米晶.研究表明,在一定范围内,成核剂使用量增加或者反应时间延长都会导致产物的粒度变大,因此通过调节成核荆的使用量和反应时间从而实现对CdS纳米晶的可控生长. 相似文献
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Na LiXiaoling Zhang Shutang ChenXiaomiao Hou Yu LiuXiaoman Zhai 《Materials Science and Engineering: B》2011,176(8):688-691
CdS nanorods and CdSe nanocrystals were prepared via the one-pot synthesis approach in oleylamine (OLA) system. The OLA used in this process as both the solvent and stabilizer is favorable for probing capping mechanism and simplifying experimental steps. The growth process and characterization of cadmium chalcogenide nanocrystals were determined by X-ray diffraction (XRD), transmission electron microscopy (TEM), Ultraviolet-visible (UV-vis) spectroscopy and photoluminescence (PL) spectroscopy. Results demonstrated OLA-capped CdS nanorods and CdSe nanocrystals were highly crystalline and had good optical properties. 相似文献
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In this study, we have examined the transfection of aqueous CdS quantum dots (QDs) in the cytoplasm of PC12 neuronal cells using polyethylenimine (PEI) as carrier. The CdS QDs were prepared using a unique aqueous synthesis method, at 5?nm in size and capped with 3-mercaptopropyltrimethoxysilane (MPS). They exhibited a quantum yield of 7.5% and a zeta potential of -25?mV. With PEI they formed complexes by electrostatic attraction. At PEI/QD number ratios of>100, the PEI-QD complexes obtained exhibited a saturated size of about 24?nm and a zeta potential of about 15?mV. Confocal microscopy showed that PEI-QD complexes of a PEI/QD number ratio of 200 were successfully internalized and uniformly distributed inside the cells, indicating that the PEI-QD complexes were able to rupture the vesicles to enter the cytoplasm without aggregation. In addition, we showed that the presence of the PEI did not reduce the photoluminescence of the QDs and only mildly reduced the mitochondrial activity of the transfected cells-with no apparent reduction at a PEI/QD ratio of <40 to about 30% reduction at a PEI/QD number ratio of 200. 相似文献
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J.C. Ferrer A. Salinas-Castillo J.L. Alonso S. Fernández de Ávila R. Mallavia 《Materials Letters》2009,63(6-7):638-640
Nanocrystals of cadmium sulfide have been synthesized in a series of aqueous solutions with a fixed concentration of polyvinyl alcohol and a variable amount of sodium polyphosphate. Optical absorption and photoluminescence measurements have been performed in order to determine the optical properties of the colloidal solutions. Transmission electron microscopy has been used to obtain structural information of the nanocrystals. The results show two different behaviors as the amount of sodium polyphosphate is increased in the solutions. The photoluminescence of nanocrystals in a polyvinyl alcohol solution without sodium polyphosphate is quenched. The addition of this co-stabilizer activates the luminescence, being more intense and blue-shifted as the amount of sodium polyphosphate is increased. However, further additions of this product beyond a sodium polyphosphate–polyvinyl alcohol weight ratio of 6.25 · 10? 3:1 leads to the inverse behavior. Transmission electron microscopy measurements indicate that a deagglomeration of the particles is produced as the amount of sodium polyphosphate is increased. 相似文献
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Angshuman Nag Sameer Sapra Subhra Sen Gupta Ankita Prakash Ajit Ghangrekar N. Periasamy D. D. Sarma 《Bulletin of Materials Science》2008,31(3):561-568
We have synthesized Mn-doped CdS nanocrystals (NCs) with size ranging from 1.8–3 nm. Photoluminescence (PL) spectra of the
doped NCs differ from that of the undoped NCs with an additional peak due to Mn d-d transitions. Electron paramagnetic resonance spectra along with X-ray absorption spectroscopy and PL spectra confirm the
incorporation of Mn in the CdS lattice. The fact that emissions from surface states and the Mn d levels occur at two different energies, allowed us to study the PL lifetime decay behaviour of both kinds of emissions. 相似文献
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《Materials Chemistry and Physics》2007,101(2-3):247-250
A simple ultraviolet photochemical reduction synthetic approach to preparing CdS nanocrystals with different morphologies is described. Sodium dodecyl sulfate (SDS) was used as soft template for the chemical synthesis of CdS nanocrystals in a mixture solution at room temperature. It was found that the magnetic force stirring and the volume proportions of C2H5OH and H2O had marked influences on the morphology of CdS nanocrystals (such as spherical, acicular-like, rod-like and worm-like shapes). The formation of CdS is via precipitation of Cd2+ ions with the homogeneously released S2− ions from decomposition of thioacetamide under ultraviolet irradiation source. X-ray diffraction (XRD), scanning electron microscopy (SEM) and the ultraviolet–visible (UV–vis) absorption spectra were employed to characterize the products. This novel method is expected to produce various semiconductor nanocrystals with potential applications in the fields of materials science and photovoltaic cells, etc. 相似文献
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Viswanatha R Sapra S Amenitsch H Sartori B Sarma DD 《Journal of nanoscience and nanotechnology》2007,7(6):1726-1729
In this work, we report the study of growth of CdS as well as ZnS nanocrystals using in-situ small angle X-ray scattering (SAXS) technique, in presence of thio-glycerol as capping agent. We observe that the diameter of the nanocrystal is controlled between 1 and 3 nm by varying the temperature of the reaction. Further, the self-focusing of the size distribution can be observed and is more pronounced at higher temperatures reducing its relative width from 25% to 10%. 相似文献
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《Journal of Experimental Nanoscience》2013,8(1):94-103
ABSTRACTThe photoluminescence of aqueously synthesised core/shell CdTe/CdS quantum dots (QDs) was investigated. Two molar ratios (2.4 and 1.3) of thioglycolic acid (TGA) to Cd2+ were compared to determine the best synthesis conditions for high photoluminescent quantum yield (PLQY) and photostability. A difference in the PLQY of the CdTe/CdS QDs was observed when CdS shells were grown with different TGA/Cd2+ ratios. The difference in the observed PLQY was attributed to the quality of the passivation of the CdTe during the CdS shell growth. At TGA/Cd2+ ratio of 1.3, the CdS shell forms through homogeneous nucleation, which is limited by diffusion of growth material from the solution onto the QDs surface. Due to the lattice mismatch of CdTe and CdS, the core will experience coherence strain resulting in dislocation sites and surface defects between nucleation sites which can result in non-radiative trap states. When the TGA/Cd2+ ratio is 2.0, the CdS shell grows epitaxially, minimising the number of surface trap states. Finally, we observed that the fluorescence intermittency was supressed for CdTe QDs after UV light illumination, attributed to annealing of deep surface trap states by UV light. 相似文献
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R.S. Sonawane 《Materials Research Bulletin》2008,43(3):618-624
A new phosphate glass system with CdS nanocrystals dispersed in glass matrix was investigated. The phosphate glass composition with good stability has been used for preparation of CdS doped glasses. The CdS in the range of 0.5-7.0% has been doped into this glass composition. Effect of CdS content on the optical and other properties has been investigated. The optical characterization of the glass samples showed that with increasing concentration of CdS, there was a red shift in transmission cut-off of the glasses. From the transmission cut-off of each glass sample, the band gap of the CdS nanocrystals embedded glass was calculated. The band gap of CdS particles embedded glass was observed in the range of 3.1-4.1 eV. The present system is compared with CdS nanocrystals doped in silica based glass system. In the phosphate glass system, the UV transmission cut-off's are not sharp and the optical transmittance decreases with increasing CdS content in contrast to silica glass system. The reason for such behavior has been discussed in the present investigation. TEM of the CdS doped phosphate glasses showed CdS particle size in the range of 5-7 nm for lower concentration of CdS and 10-100 nm for higher concentration of CdS. The nanocrystals are non-uniform in size but uniformly dispersed in glass matrix. 相似文献
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Changes in electronic and photovoltaic properties of semiconductor nanocrystals predominantly due to changes in shape are discussed here. Cadmium sulfide (CdS) semiconductor nanocrystals of various shapes (tetrapod, tetrahedron, sphere and rod) obtained using an optimized solvothermal process exhibited a mixed cubic (zinc blende) and hexagonal (wurtzite) crystal structure. The simultaneous presence of the two crystal phases in varying amounts is observed to play a pivotal role in determining both the electronic and photovoltaic properties of the CdS nanocrystals. Light to electrical energy conversion efficiencies (measured in two-electrode configuration laboratory solar cells) remarkably decreased by one order in magnitude from tetrapod --> tetrahedron --> sphere --> rod. The tetrapod-CdS nanocrystals, which displayed the highest light to electrical energy conversion efficiency, showed a favorable shift in position of the conduction band edge leading to highest rate of electron injection (from CdS nanocrystal to the wide band gap semiconductor viz. titanium dioxide, TiO2) and lowest rate of electron-hole recombination (higher free electron lifetimes). 相似文献
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In this paper we report a novel synthesis method of blue fluorescence CdS quantum dots stabilized by L-cysteine in aqueous phase. When pH value of the core/shell CdTe/CdS colloid solution changed from 11.6 to 1.5, blue fluorescence CdS QDs was obtained. The fluorescence emission wavelength yielded a hypsochromic shift from 540 nm to 438 nm corresponding to the absorption peak position gave a hypsochromic shift from 518 nm to 352 nm. The CdS QDs were characterized by XPS and TEM. And the photostability of CdS QDs solution irradiated with UV lamp under open air condition at room temperature was very stable. 相似文献
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CdS nanocrystals coated with protein were synthesised in the aqueous solution of bovine serum albumin protein by a rapid microwave-assisted hydrothermal method. Transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and cell cytotoxicity were used to characterise the morphology, composition and properties of the nanocrystals. The results indicate that the as-prepared CdS nanocrystals were wrapped up with the protein. The cytotoxicity profile on the human cervical cancer cell line HeLa shows that the potential cellular toxicity of the nanocrystals is efficiently prevented due to the presence of protein coating, which may offer the possibility of applications in biomedical research. 相似文献
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We demonstrated simple solution based methods for preparing CdS nanostructure materials with distinct and well-defined morphologies, including spherical, rod and tripod/tetrapod by varying the solvents. It is also found that solvent plays an important role on tuning the crystal structure of nanocrystals, which is an important observation in this study. The mechanism related to crystal phase control is proposed and discussed. Our results reveal that the luminescence properties of CdS nanostructures depend on the size not on the shape of nanocrystals. 相似文献