Fabrication of CdS nanorods in inverse microemulsion using HEC as a template by a convenient γ-irradiation technique

Cadmium sulfide (CdS) nanocrystals were successfully prepared in inverse microemulsion under γ-irradiation at room temperature. Their shape can be controlled by changing the surfactant concentrations and the addition of hydroxyethyl cellulose (HEC) as the template. CdS nanorods were successfully obtained under γ-irradiation using HEC as the template, which was confirmed by the observation of transmission electron microscopy (TEM). Without the addition of HEC, spherical CdS crystals were formed. X-ray powder diffraction (XRD) pattern and electron diffraction (ED) analysis showed the hexagonal lattice of CdS in the nanorods. Additionally, the optical properties of CdS nanorods were characterized by ultraviolet–visible (UV–Vis) and photoluminescence (PL) spectroscopy.     

Synthesis and spectral properties of starch capped CdS nanoparticles in aqueous solution

Synthesis of cadmium sulphide nanoparticles has been carried out in aqueous solution precipitation. Starch added during the synthesis of the nanoparticles resulted in cadmium-rich nanoparticles forming a stable complex with starch. The morphology and crystalline structure of such structures were measured by high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD), respectively. The grain size of the nanoparticles determined by these techniques was of the order of 5 nm, which correlates well with measurements performed by Raman scattering and photoacoustic spectroscopy.     

Hydrothermal synthesis of ZnSe hollow micropheres

ZnSe hollow spheres aggregated from nanoparticles with size of 60∼100 nm have been successfully synthesized via simple hydrothermal routes. NaOH and cetyltrimethyl ammonium bromide (CTAB) were used to control the shape and size, respectively. The as‐prepared microspheres were characterized with powder X‐ray diffraction (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV‐vis spectroscopy. The results indicate that the products are well dispersed and uniform. The effect of two additives was discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Sol–gel preparation and photoluminescence properties of Ce-activated Y3Al5O12 nano-sized powders

Trivalent cerium-doped yttrium aluminum garnet (YAG:Ce³⁺) nanoparticles were successfully prepared by a facile sol–gel technique. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy were used to characterize the as-prepared phosphors. Well-crystallized fine nanoparticles were obtained at 1000 °C. Single-crystal nanoparticles with irregular shapes were obtained, with crystallite sizes ranging between 20 and 60 nm. PL intensity of the particles increased monotonically with decreasing Ce doping concentration and showed the maximum value at 0.1 at%.     

TiOCl2溶液微波加热制备金红石型TiO2纳米粒子

本文报道了一种由TiOCl2液相直接合成金红石型TiO2纳米粒子的新方法,即微波诱导沸腾回流强迫水解法,用该法制备出常规条件下不能得到的产品.所得产物用粉末X射线衍射仪和透射电子显微镜表征,证明产物为金红石型,粒子尺寸5～30nm可控.研究表明,产物物相取决于Ti4+的初始水解速率,水解速率越快,越有利于金红石相成核;通过控制初始Ti4+的浓度,可改变纳米TiO2的粒径.另外还讨论了该金红石型TiO2纳米粒子的成核机理.     

直流电弧等离子体制备NiO纳米颗粒研究

采用直流电弧等离子体技术成功制备了NiO纳米颗粒,并利用X射线衍射(XRD)、透射电子显微镜(TEM)和相应选区电子衍射(SAED)、傅里叶变换红外光谱(FTIR)、BET氮吸附等测试方法对样品的成分、形貌、晶体结构、比表面积、粒度分布、红外吸收性能进行表征分析.实验结果表明:直流电弧等离子体制备的NiO纳米颗粒为fcc结构的晶态,形貌呈规则的球形,粒度均匀,分散性良好,粒径范围在15～45 nm,平均粒径为25 nm,比表面积为33 m2/g.与普通块体NiO相比,红外吸收峰发生了红移.     

Synthesis of Nb2O5·nH2O nanoparticles by water-in-oil microemulsion

Hydrous niobium oxide (Nb₂O₅·nH₂O) nanoparticles had been successfully prepared by water-in-oil microemulsion. They were characterized by X-ray diffraction (XRD), thermal analysis (TG/DTG), Fourier transform infrared spectroscopy (FTIR), BET surface area measurement, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that the nanoparticle was exactly Nb₂O₅·nH₂O with spherical shape. Their BET surface area was 60 m² g⁻¹. XRD results showed that Nb₂O₅·nH₂O nanoparticles with crystallite size in nanometer scale were formed. The crystallinity and crystallity size increased with increasing annealing temperature. TT-phase of Nb₂O₅ was obtained when the sample is annealed at 550 °C.     

Synthesis and optical properties of high-purity CoO nanowires prepared by an environmentally friendly molten salt route

CoO nanowires with diameters of 50^_80 nm, and lengths of up to more than 5 μm have been successfully synthesized by a simple environmentally friendly molten salt route, in which the precursor CoCO₃ nanoparticles are decomposed to form high-purity CoO nanowires in NaCl flux. The structure features and morphology of the as-prepared CoO nanowires were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and selected area electron diffraction (SAED). The chemical composition and oxidation state of the prepared nanowires were systemically studied by X-ray photoelectron spectra (XPS) and laser Raman spectroscopy. The results indicated that the as-prepared CoO nanowires were composed of pure cubic CoO phase. The growth mechanism of the synthesized nanowires was also discussed in detail based on the experimental results.     

Controlled synthesis of PAN/Ag2S composites nanofibers via electrospinning-assisted hydro(solvo)thermal method

The Ag₂S nanoparticles embedded in polyacrylonitrile (PAN) fibers matrix were successfully prepared by the combining electrospinning with the hydro(solvo)thermal process, without the presence of any templates or organic surfactants. What's more, the size and content of Ag₂S nanoparticles was tunable through proper controlling of the reaction conditions. Consequently, the Ag₂S nanoparticles with 10-100 nm diameter could be obtained via this two-step synthetic route. The as-synthesized composites nanofibers were investigated by X-ray diffraction(XRD), field-emission scanning electronic microscopy (FE-SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), Fourier transform infrared spectroscopy (FT-IR), and photoluminescence( PL), respectively. What's more, a possible formation mechanism of Ag₂S nanoparticles grown on PAN nanofibers was also proposed.     

Stability of ruthenium nanoparticles synthesized by solvothermal method

One of the major obstacles to the synthesis of nanoparticles and nanocatalyst is the stability of particles. In the present study, polymer stabilized ruthenium nanoparticles were synthesized by solvothermal method using solutions of ruthenium chloride in ethylene glycol in presence of poly(N ‐vinyl‐2‐pyrrolidone) (PVP) as a stabilizing agent. Stability of nanoparticles was studied by varying different parameters e.g. PVP/RuCl₃ molar raio, RuCl₃ concentration, reaction temperature and time and expressed in terms of particle size and size distribution. Transmission electron microscope (TEM) analysis revealed the presence of metallic clusters with a uniform size of about 20‐65 nm. Dispersion destabilisation of colloidal nanoparticles was detected by Turbiscan. Polymer stabilized ruthenium nanoparticles were dispersed on γ‐alumina to prepare uniformly disperse Ru/γ‐Al₂O₃ catalyst by mechanical strirring and sonication. Inductively coupled plasma‐optical emission spectroscopy (ICP‐OES), X‐Ray powder diffraction (XRD), Transmission electron microscopy (TEM) and Thermo gravimetric analysis (TGA) were used to characterize the supported catalyst. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Self-assembly of highly crystalline spherical BiVO4 in aqueous solutions

Spherical bismuth vanadate particles are self-assembled from aqueous Bi(NO₃)₃ and NH₄VO₃ solutions by adjusting pH and tuning the amount of surfactant sodium dodecyl sulfate (SDS) via facile hydrothermal method. The BiVO₄ samples were characterized by X-ray diffraction (XRD) and the peaks suited well with the pure phase monoclinic scheelite BiVO₄. Field emission scanning electron microscopy (SEM) showed the average size of the spherical particles was 5 μm and the assembling stages in the hydrothermal synthesis process were recorded. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) revealed the nanoparticles were single crystal. FT-IR spectroscopy test results demonstrated there was no SDS left in the samples. The mechanism of the self-assembling has also been proposed.     

Synthesis by precipitation method and investigation of SnO2 nanoparticles

In this paper the synthesis of SnO₂ nanoparticles with average particle size up to about 70 nm using SnCl₂2H₂O and NH₄OH in 1‐botanol solution by the precipitation method is reported and the inhibition of sodium dodecyl sulphate (SDS) on the SnO₂ particle growth is investigated by soaking SnO₂precursor in the SDS solution for 24 h. The as‐prepared SnO₂and SDS modified‐SnO₂ powders, then, were calcined at different temperatures and the X‐ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FT‐IR) were used to characterize the output samples. The XRD results reveal that the structure of tin‐dioxide is tetragonal rutile and the as‐prepared SnO₂ nanoparticles grow with increasing the annealing temperature, while the SDS treatment prevents the particle growth under the same condition. Furthermore, the FT‐IR results indicate the formation of tin‐hydroxyl group which are then converted into tin‐dioxide with heat treatment. Further characterization of the samples by the transmission electron microscopy (TEM) and the photoluminescence (PL) spectroscopy was carried out. The room temperature PL spectra of SnO₂exhibits broad and strong peak attributed to the surface defects such as oxygen vacancies and intensity of which decreases with the increase in particle size. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Production and Study of Silver Nanoparticles by 532 nm Laser Pulse Ablation in NaCl Solution

In this experimental research, silver nanoparticles are produced in NaCl solution by the laser ablation method. Our aim was to investigate the effect of the amount of NaCl in the ablation medium on the characteristics of nanoparticles. A 7 ns pulsed Neodymium YAG laser (Nd:YAG) at 5 J/cm2 fluence and 532 nm wavelength was employed to produce Ag nanoparticles in distilled water with four different concentrations of NaCl. The optical properties, size distribution, and agglomeration of nanoparticles were investigated by several diagnostics. The UV–Visible absorption spectra of the Ag nanoparticles exhibit absorptions in the UV region because of surface plasmon resonance. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to study the size distribution and morphology of nanoparticles. Dynamic light scattering (DLS) was employed to measure the hydrodynamic size of nanoparticles in suspensions. With X-ray diffraction (XRD) pattern, the lattice structure of nanoparticles was studied. Fourier transform infrared (FTIR), photoluminescence (PL) spectra were obtained to observe the molecular structure and atomic energy levels of particles.     

自蔓延燃烧法制备ZrO2纳米粉体

以氧氯化锆为原料,采用一种低温而且快速的溶胶凝胶自蔓延燃烧法制备了纳米ZrO2粉体颗粒,通过X射线衍射仪(XRD)和透射电镜(TEM)分析探讨了柠檬酸与金属离子的物质的量比和杂质离子NH;和Cl-的存在对ZrO2粉体颗粒的形成和粉末晶粒尺寸大小的影响.本次试验成功的制备了粒径为30～90 nm的近球形ZrO2纳米颗粒,试验结果表明,NH4+和Cl-两种离子的存在阻碍了ZrO2粉体长大形成更大的颗粒,柠檬酸与金属离子的物质的量比例越大,燃烧产生的瞬间高温越容易使ZrO2粉体颗粒长大.     

Synthesis and characterization of a micro scale zinc oxide–PVA composite by ultrasound irradiation and the effect of composite on the crystal growth of zinc oxide

Micro scale zinc oxide-polyvinyl alcohol (ZnO–PVA) composite has been synthesized by ultrasound irradiation. The properties of the as-prepared ZnO–PVA composite material are characterized by X-ray diffraction (XRD), thermo gravimetric analysis (TGA), transmission electron microscopy (TEM), and diffuse reflection spectroscopy (DRS). A band gap of 3.25 eV is estimated from DRS measurements. The controlled crystal growth of zinc oxide has been studied by using the as-prepared micro scale ZnO–PVA composite as seeds for the crystal growth of ZnO.     

Size-controlled synthesis of LaAlO3 by reverse micelle method: Investigation of the effect of water-to-surfactant ratio on the particle size

Lanthanum monoaluminate (LaAlO₃) nanoparticles have been synthesized using microreactors made of poly(oxyethylene) nonylphenyl ether (Igepal CO-520)/water/cyclohexane microemulsions. The control of particle size was achieved by varying the water-to-surfactant molar ratio. The synthesized and calcined powders were characterized by thermogravimetry–differential thermal analysis (TGA-DTA), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). Differential thermal analysis showed that LaAlO₃ phase transformation decreases with increase in water/surfactant (R) value. Pure LaAlO₃ phase was synthesized by annealing at 800 °C for 2 h in air directly from amorphous precursors, without formation of intermediate phase. The average particle size was found to increase with increase in water-to-surfactant ratio (R). FTIR analysis was carried to monitor the elimination of residual oil and surfactant phases from the microemulsion-derived precursor and calcined powder.     

微波固相反应前驱体热分解法制备纳米氧化铜粉体

将固体CuSO4·5H2O和Na2CO3混合均匀后溶于适量乙醇中,然后进行微波辐照,立即反应生成泥浆状固体,将该泥浆状固体洗涤后干燥即可得到粉状前驱体.然后在600 ℃加热1 h分解该前驱体,即可制得纳米氧化铜粉体.在加热速率为10 ℃/min的条件下,对该前驱体进行表征,发现其热分解和晶体化温度约为550 ℃.对制得的纳米氧化铜粉体进行XRD、SEM、TEM和IR分析,结果表明制得的产物为纳米氧化铜粉体,其粉体粒径在30～50 nm,平均粒径约为40 nm.     

Facile electrochemical synthesis of tellurium nanorods and their photoconductive properties

Tellurium nanorods have been successfully fabricated by template and surfactant‐free electrochemical technique from an aqueous solution at room temperature. The as‐prepared tellurium nanorods were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectrometry, UV‐vis spectroscopy and photoluminescence spectroscopy. Films based on tellurium nanorods were constructed to study the photoresponse and I‐V curves. These photoresponse measurements demonstrate that tellurium nanorods exhibited enhanced conductivity under illumination compared to in the dark measurement.     

Effect of citric acid and starch as emulsifier on phase formation and crystallite size of lanthanum oxide nanoparticles

Lanthanum oxide nanoparticles were synthesized via thermal decomposition method of the lanthanum nitrate in the presence of citric acid or starch as emulsifier. The effects of emulsifier and calcination temperature were investigated on the phase transformation and particle size distribution of the products. La₂O₃ nanoparticles were synthesized by drying lanthanum precursor and emulsifier solution, followed by calcination process at 600 and 900°C, respectively. Products were characterized by Fourier Transform Infrared (FT‐IR) spectroscopy, X‐ray diffraction (XRD), thermal analysis (TG/DTA) and nitrogen adsorption method (porous characteristics). The morphology of the samples analyzed using scanning electron microscopy (SEM). Average crystallite size of the products was calculated by XRD data and average particle size was measured from the TEM micrographs. Lanthanum dioxycarbonate in different forms of the tetragonal and monoclinic is crystallized in the presence of citric acid and starch during the calcination at 600°C, respectively. The hexagonal structure, however, is detected as the only crystalline phase formed by calcination at 900°C.     

CdS纳米棒的水热法制备及形成机理研究

采用水热法以Na2S· 9H2O为硫源,Cd3O12S3·8H2O为镉源,PVP为表面活性剂,成功制备了CdS纳米棒.并利用X射线衍射(XRD)、透射电子显微镜(TEM)和相应选区电子衍射(SAED)、高分辨透射电子显微镜(HRTEM)、X射线能量色散分析谱仪(XEDS)和紫外可见(UV-vis)分光光度计等测试手段对样品的晶体结构、形貌、微观结构和光学特性等特征进行了表征分析,实验结果表明本方法所制备的CdS纳米棒为纤锌矿结构,沿[001]方向择优生长,平均直径大约为50 nm,棒宽均匀、分散性好,带隙为2.43 eV.同时也对CdS纳米棒的形成机理进行了初步探讨,提出了CdS纳米棒的生长模型,其形貌从三角形到阶梯形棒晶,最后再到完整的棒状晶体的一个定向团聚的自组装过程.