Growth of PbTe nanorods controlled by polymerized tellurium anions and metal(II) amides via composite-hydroxide-mediated approach

The pure face-centered-cubic PbTe nanorods have been synthesized by the composite-hydroxide-mediated approach using hydrazine as a reducing agent. The method is based on reaction among reactants in the melts of potassium hydroxide and sodium hydroxide eutectic at 170-220 °C and normal atmosphere without using any organic dispersant or surface-capping agent. Scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and energy dispersive X-ray spectroscopy were used to characterize the structure, morphology and composition of the samples. The diameters of nanorods are almost fixed, while the lengths can be tunable under different growth time and temperatures. The growth mechanism of PbTe nanorods is investigated via UV-vis absorption, demonstrating that polymerized tellurium anions and metal(II) amides in the hydrazine hydroxide melts could control the crystallization and growth process of PbTe nanostructures. The band gap of as-synthesized PbTe nanorods has been calculated based on UV-vis-NIR optical diffuse reflectance spectra data.     

Catalytic synthesis of large-scale GaN nanorods

A novel rare earth metal seed was employed as the catalyst for the growth of GaN nanorods. Large-scale GaN nanorods were synthesized successfully through ammoniating Ga₂O₃/Tb films sputtered on Si(1 1 1) substrates. Scanning electron microscopy, X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy were used to characterize the structure, morphology, and composition of the samples. The results demonstrate that the nanorods are high-quality single-crystal GaN with hexagonal wurtzite structure. The growth mechanism of GaN nanorods is also discussed.     

Synthesis and characterization of the tellurium/calcium silicate nanocomposite

A novel tellurium/calcium silicate nanocomposite with tellurium nanorods homogeneously dispersed in the calcium silicate matrix has been successfully synthesized using corresponding tellurium nanorods, Ca(NO₃)₂·4H₂O, and Na₂SiO₃·9H₂O in ethanol/water mixed solvents at room temperature for 48 h. The new material consists of a single crystalline Te core and an amorphous calcium silicate shell. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and energy-dispersive X-ray spectroscopy (EDS). The method is simple and does not need any surfactant or template or base. Cytotoxicity experiments indicated that the tellurium/calcium silicate nanocomposites with a low concentration had good biocompatibility. This nanocomposite is a very promising candidate for the application as bioactive materials.     

Highly monodispersed ZnO nanorods: preparation and optical properties

Simple and low cost solution synthesis method was used to synthesise ZnO nanorods. Dodecyl benzene sulfonate was used to control the growth process and monodispersed nanorods with diameters in the range of 25 to 44 nm were obtained. X-ray diffraction, transmission electron microscopy and high resolution transmission electron microscopy measurements demonstrate the structure and morphology of the products. Laser power- and temperature-dependent photoluminescence (PL) experiments confirm the good ultraviolet emission characteristics. Short exciton lifetime feature relevant to thin nanorods was examined by time-resolved PL. Good optical quality and the size characteristics of the obtained products are discussed.     

Morphology evolution of tungsten trioxide nanorods prepared by an additive-free hydrothermal route

Tungsten trioxide nanorods were prepared at 453 K by the hydrothermal treatment of aqueous tungstic acid sol, which was obtained by sodium tungstate solution passing through a strongly acidic ion-exchange resin in its proton form. The composition and morphology evolution of the nanorods were investigated by means of scanning electron microscopy, transmission electron microscopy, selected area electron diffraction and X-ray diffraction. The results show that all as-prepared samples mainly consist of hexagonal tungsten trioxide and tungsten trioxide one-third hydrate. With the extension of treatment time, the sample morphology will undergo an evolution in the sequence of nanorod, bundle-like and irregular shapes.     

Bi_2Te_3纳米粉末的直流电弧等离子体合成

以单质Bi,Te粉末为原材料,采用直流电弧等离子体蒸发法制备了Bi2Te3纳米粉末。通过XRD,EDS,TEM和SAED分析方法对Bi2Te3粉末的物相结构、成分和形貌进行了表征。Bi2Te3纳米粉末的平均粒径约为35 nm,粉末呈不规则的多面体结构,还有一些薄片状和棒状的结构,这与Bi2Te3半导体化合物的高度各向异性是一致的。研究了电弧电流和氩气压力对合成Bi2Te3纳米粉末的粒径和产率的影响,随着电弧电流或氩气气压的增加,粉末的粒径和产率都逐渐增大,但产率的增加并不明显。     

Growth of ZnO nanocrystals by a solvothermal technique and their photoluminescence properties

ZnO nanocrystals with various morphologies such as nanorod arrays, flower like assemblies, spherical particles, hexagonal cones, and self assembled microstructures were prepared by a solvothermal approach. It was observed that morphology of the ZnO nanostructures were very much solvent dependent in solvothermal approach. Water, ethylenediamine, and ethylene glycol-water mixture favors the formation of nanorods. Flower like assemblies of ZnO were produced in benzene. Spherical as well as cone like nanoparticles and their assemblies were produced in ethylene glycol. The ZnO nanostructures were characterized by X-ray diffraction, scanning and transmission electron microscopy, and photoluminescence studies.     

A new route to synthesis of γ-alumina nanorods

γ-Alumina single-crystalline nanorods have been successfully synthesized by thermal decomposition of boehmite precursor which was prepared by solvothermally treating AlCl₃ ⁎ 6H₂O, NaOH, sodium dodecyl benzene sulfonate in water and dimethylbenzene mixed solvents. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Our experiments show that the surfactant plays an important role in the morphology and assembly of boehmite. Photoluminescence (PL) spectrum of the boehmite nanorods was also investigated.     

A Novel Hydrothermal Synthesis of Single Crystalline PbS Nanorods and Their Characterization

1.IntroductionDuring the past decade,one-dimensional(1D)nanos-tructures,such as nanorods,nanowires,nanobelts andnanotubes,have attracted increasing attentions due totheir novel electrical,optical and magnetic properties,and their potential applications in nanoscale eletronics,photonics and functional materials[1~3].Great effortshave been made to prepare1D semiconductor nanostruc-tures such as Si nanowires[4],ZnO nanorods[5]and GaNnanowires[6].At the same time,chalcogenide nanostruc-tures su…     

Fabrication of CdTe/Te hetero-nanostructures by vapor-solid process

CdTe/Te core-shell heterostructures were fabricated by the vapor phase synthesis at low temperatures using a quartz tube furnace. Two step vapor-solid processes were employed. First, various tellurium structures such as nanowires, nanorods, nanoneedles, microtubes and microrods were synthesized under different deposition conditions. These tellurium nanostructures were then used as substrates in the second step to synthesize the CdTe/Te core-shell heterostructures. Using this method, various sizes, shapes and types of CdTe/Te core-shell structures were fabricated under a range of conditions. The temperature, pressure and gas flow rate were very important parameters for synthesizing these nanostructures in the vapor phase process. The morphology, crystal structure and orientation were characterized by field-emission scanning microscopy, field-emission transmission electron microscopy and X-ray diffraction. The vapor phase process at low temperatures appears to be an efficient method for producing a variety of Cd/Te hetero-nanostructures. In addition, the hetero-nanostructures can be tailored to the needs of specific applications by deliberately controlling the synthetic parameters.     

Template-free hydrothermal synthesis of PbS nanorod by the oriented attachment mechanism

In this work, PbS nanocubes and nanorods were fabricated via a facile hydrothermal method without using any template and surfactant. The structure and morphology of as-prepared PbS nanocrystals were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). It was found that the anisotropic structure of PbS nanorods were composed of numerous assembled nanocubes, which had an uniform morphology with the mean diameters of about 100-200 nm and lengths of 0.5-7 μm. Furthermore, a possible growth mechanism was proposed to explain the formation of the nanorods on the basis of the time-dependent experimental results.     

Soft-template mediated synthesis of GaOOH nanorod-shelled microspheres and thermal conversion to beta-Ga2O3

Micrometer-scale hollow spheres self-assembled by GaOOH nanorods were synthesized under hydrothermal conditions using gallium nitrate and sodium hydroxide as starting materials. The structures and morphologies of the products were studied by X-ray diffraction and scanning electron microscopy. Time-dependent experiments revealed three stages involved in the process of reaction including the initial stage of formation of surfactant vesicles which can be considered as soft templates, followed by the nucleation of GaOOH nanoclusters, and the assembling and growth of nanorods under the modulation of the spherical vesicles. The growth kinetics of the GaOOH nanorods was systematically investigated. Based on the experimental observation, a template-mediated assembling mechanism was proposed. We further demonstrated that the GaOOH nanorods could be converted to gallium oxide (beta-Ga2O3) nanorods by calcination without changing the spherical morphology of the assemblies.     

Solvothermal preparation of cobalt nanorods

Cobalt nanorods have been prepared through solvothermal process with hydrazine hydrate and dimethylglyoxime (DMG) as reducing and morphology directing agents. The phase structure, morphology and magnetic properties of the as-prepared product were extensively characterized by X-ray diffraction, transmission electron microscopy and superconducting quantum interference device magnetometer. X-ray diffraction pattern revealed that the as-synthesized product was cobalt with face-centered cubic structure. Transmission electron microscopy observation showed that the as-prepared product composed of rod-like shape with size around 10 nm. The presence of DMG molecules on the surface of Co nanostructures was confirmed by the FTIR spectra. Magnetic measurements revealed that the nanorod exhibit ferromagnetic behavior at 300 K. The coercive force value of cobalt nanorods is 340 Oe at 300 K. Compared with bulk cobalt, the nanorods exhibit significant increase in coercive force as a reflection of shape anisotropy. The saturation magnetization value of Co nano rod is 150 emu/g at room temperature.     

Silver nanorods using HEC as a template by γ-irradiation technique and absorption dose that changed their nanosize and morphology

Silver (Ag) nanorods with average diameters of 20 nm and lengths up to 250 nm were successfully prepared in large scale using hydroxyethyl cellulose (HEC) as a template reducing silver nitrate by γ-irradiation. When we changed the irradiation time to get a different absorption dose at the same dose rate, we can find that the silver nanorods have been transferred into a larger size and another morphology. The particle size and morphology can be changed by choosing different absorption doses under the same dose rate. The products were characterized by transmission electron microscopy (TEM), electron diffraction (ED) analysis, field-emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).     

A simple route to lanthanum hydroxide nanorods

This letter first describes a facile, low-cost, solution-phase approach to the large-scale preparation of lanthanum hydroxide single crystal nanorods at 60 °C without any template and surfactant. X-ray diffraction (XRD) shows that the nanorods are of pure hexagonal structure. The size and morphology of the products were examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Lanthanum hydroxide single crystal nanorods are with diameters of approximately 20 nm and lengths of 150-200 nm. The processes of formation and decomposition for the as-prepared lanthanum hydroxide nanorods were discussed.     

Synthesis of Sb2E3 (E = S, Se) nanorods with a flat cross section by a rapid hot injection method

We report herein a simple colloidal synthesis route, i.e., rapid injection of E (E = S, Se) source into a hot solvent (1-octadecence, ODE) containing antimony precursor (antimony stearate), to grow Sb2E3 nanorods. The as-prepared nanorods were extensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and high-resolution transmission electron microscopy (HRTEM). The mechanism for growth of Sb2E3 nanorods was also clarified from the view of crystal structure-directed growth. We believe that the method present here is a more straightforward and cost-effective route to prepare Sb2E3 nanocrystals with high quality.     

SnO2纳米棒的制备及表征

在聚氧乙烯五醚（NP5），聚氧乙烯九醚（NP9），乳化剂（OP）和环己烷组成的微乳体系中制备二氧化锡前驱物。然后再经800－820℃熔烧2.5h，成功地制备了直径为30－90nm，长5－10μm的金红石结构的二氧化锡纳米棒，并用透射电子显微镜，电子衍射，X射线衍射对二氧化锡纳米棒的结构进行了表征。用熔盐合成机理对其形成进行了讨论，初步认为是成核、长大过程形成了二氧化锡纳米棒。     

Synthesis, Characterization and Gas Sensing Properties of In（OH）3 and In2O3 Nanorods through Carbon Spheres Template Method

Poly-crystalline In(OH) 3 nanorods have been successfully prepared via a urea-based precipitation using the colloidal carbon spheres as the templates. After calcinations, the resulted In 2 O 3 nanorods with poly-crystalline structure were fabricated. Structure and morphology of the product were characterized by X-ray diffraction (XRD), and transmission electron microscopy (TEM). The possible formation process was schemed. The sensor gas properties towards C 2 H 5 OH and CO were examined.     

A facile method to prepare PbS nanorods

PbS nanorods with an average diameter of about 30 nm have been successfully prepared through a simple polyglycol-assisted route for the first time. The obtained PbS nanorods have been characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electronic diffraction (SAED). Experiments show that polyglycol plays an important role for the control of the morphology of PbS nanostructures. The preliminary result of the UV-vis absorption spectrum of the PbS nanorods is also presented.     

Synthesis of SnO2 flower-like architectures by varying the hydrothermal reaction time

We successfully synthesized hierarchical SnO₂ flower-like architectures assembled with nanorods via a facile hydrothermal route under mild condition. The structures and morphologies of the obtained hierarchical architectures were characterized by means of powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy. By varying hydrothermal reaction time, we obtained the sphere-like and flower-like SnO₂. The evolution that the morphology changing from sphere-like to flower-like was systematically investigated. Moreover, the mechanism of formation for this structure was proposed in detail.