Sb_2Te_3纳米片的水热合成与表征

在水热条件下,以乙醇胺为还原剂,实现了亚碲酸根(TeO~(2-)_3)的分步还原,并以新生成的单质Te纳米棒为碲源,原位一步法合成出六方相Sb_2Te_3纳米片.采用X射线粉末衍射仪(XRD)、场发射扫描电子显微镜(FESEM)和透射电子显微镜(TEM)等对产物的物相、形貌及组成进行了表征.结果表明,产物Sb_2Te_3为六方纳米片,厚度约为100~200 nm,直径约为0.6~1.5μm,形貌均一,分散性良好.适宜的合成条件是水/乙醇胺体积比为8∶12,180℃下反应24 h.依据部分实验结果以及单质Te和六方相Sb_2Te_3晶体结构的比较,证明了Sb_2Te_3主要以外延方式在单质Te纳米棒表面生长,且两者的晶面取向为(003)Te//(003)Sb_2Te_3,[110]Te//[110]Sb_2Te_3.     

葡萄糖辅助合成碲化铅纳米棒及其表征

采用简单的葡萄糖辅助溶剂热合成法制备了碲化铅纳米棒。 利用X射线衍射(XRD)、场发射扫描电子显微镜(FE-SEM)、透射电子显微镜(TEM)、高分辨率透射电子显微镜(HRTEM)、能谱仪(EDS)等技术手段进行材料结构和形貌表征。 结果表明,产物是纯的立方相PbTe,纳米棒的直径约为50 nm,长500 nm左右。 研究了反应过程的影响因素及碲化铅纳米棒的形成机制。 产物的形貌受葡萄糖的量、反应时间、反应温度和聚乙烯吡咯烷酮(PVP)质量的控制,分析了形成这种结构的原因。     

纳米硫化镉的合成及其电化学催化性能测试

采用CS2-SDS-正辛醇-水微乳体系制备了硫化镉纳米棒。利用XRD、SEM、TEM对产物进行表征，测试了其对多硫化物电极还原反应的催化性能，并与常规方法合成的大粒度CdS晶体进行对比．结果表明，纳米棒为六方型CdS晶体，直径约12nm．常规法合成的CdS为立方型晶体，平均粒度约为1μm．CdS纳米棒电极对硫化钠／多硫化钠电极反应的电催化活性明显高于大粒度CdS晶体电极．     

硼酸镍纳米棒溶胶-凝胶法合成及表征

以硝酸镍、硼酸和柠檬酸为原料,采用溶胶凝胶法于150 ℃形成咖啡色干凝胶,再于750 ℃焙烧得到硼酸镍纳米棒。采用XRD、SEM、TEM和FTIR对产物结构和形貌进行表征。结果表明产物为分布均匀的Ni₃(BO₃)₂纳米棒,纳米棒的长度受硝酸镍和硼酸的物质的量之比影响,硼酸用量越大,长度越大。当n_Ni3(BO3)2∶n_N3BO3=1∶3时,纳米棒直径为200~300 nm,长度为2~3 μm。对硼酸镍纳米棒的生长机理进行了探讨, 结果表明, 柠檬酸与镍离子反应产生网状结构的配合物,促使镍源均匀地分散在网格间,为硼酸镍纳米棒的生成提供有利的反应空间。     

2，4-共轭不饱和酮、酯、腈的合成

前文我们报道了溴化对-苯基苯甲酰甲基二丁基碲、溴化对-溴苯甲酰甲基二丁基碲和溴化间-硝基苯甲酰甲基二丁基碲等碲盐与醛、酮缩合成α,β-不饱和酮的反应。为了进一步研究碲盐反应性能,扩大它在有机合成中应用范围,我们在前期工作基础上,由碲盐和(E)-α,β-不饱和醛合成了2,4-共轭不饱和酮、酯、腈,这是一种未见文献报道的新合成方     

反应条件对ZnWO4纳米棒的形貌和光致发光性能的影响

采用水热法合成了ZnWO4纳米棒, 并用扫描电镜(SEM)、透射电镜(TEM)和粉末X射线衍射(XRD)等技术对产物进行了表征. 实验结果表明, 反应溶液的pH值和反应时间是影响ZnWO4纳米棒形成的重要因素. 研究了不同反应条件下制备的ZnWO4纳米晶的光致发光性能.     

氢化物负压发生器—真空无火焰原子化器的原子吸收光谱法测定碲

在负压发生器中用1％NaBH_4将Te(Ⅳ)还原成碲化氢后,再加入2mL氧气,用真空泵将氧与碲化氢的混合物吸进电热真空石英管中,同时测定原子吸收光谱。加入的氧与硼氢化钠分解产生的氢反应生成水分子,消除了氢对碲的干扰。     

硼酸铝纳米棒的制备、结构及生长机理

以仲丁醇铝和硼酸为原料, 葡萄糖作模板剂, 在水介质中120 ℃形成淡黄色干凝胶, 再于750 ℃焙烧得到尺寸均一的硼酸铝纳米棒. 通过改变仲丁醇铝/硼酸的摩尔比实现了对产物形貌及长径比的控制合成. 采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)对产物结构和形貌进行表征. 结果表明产物为Al4B2O9纳米棒, 直径为15-45 nm, 长度为100-300 nm. 根据表征结果对葡萄糖参与的硼酸铝纳米棒的生长机理进行了探讨. 结果表明, 葡萄糖与硼酸反应产生网状结构的配合物, 同时释放质子, 促使铝源均匀地分散在网格间, 为硼酸铝的生成提供一有利的反应空间. 纳米棒的生长为自催化生长过程, 在750 ℃热处理时沿着(100)面方向生长.     

低温水热法制备高活性纳米金红石相二氧化钛

采用低温水热法由TiC l3溶液直接制备了纳米二氧化钛,并研究了TiC l3溶液浓度、反应温度以及陈化时间对产物晶相、晶化程度、形貌以及尺寸的影响。结果表明:TiC l3溶液浓度对晶相有较大影响,高浓度下易获得混晶,低浓度下得到纯金红石相。反应温度和陈化时间主要影响产物的晶化程度和晶体的形貌、尺寸,对生成的晶相也有一些影响。在给定的反应条件下,获得了形状规整、尺寸约为15×80nm、晶化程度高的金红石相二氧化钛纳米棒。对甲基橙的光催化降解实验表明,这种金红石纳米颗粒的催化活性与市售纳米锐钛矿相二氧化钛相近。     

PbS纳米棒束的水热合成与表征

以乙酸铅和硫脲为主要原料,十二烷基磺酸钠和十六烷基三甲基溴化铵为表面活性剂.在120℃反应12 h.水热法制备了PbS纳米棒束.并利用X射线粉末衍射(XRD)、透射电子显微镜(TEM)和高分辨电子显微镜(HRTEM)等手段对产物进行了表征.实验结果表明:产物为立方结构的PbS单晶纳米棒所组成的纳米棒束.考察了乙酸铅和硫脲的摩尔比以及反应温度对合成产物的影响,发现当乙酸铅和硫脲的摩尔比为1∶1时,得到大量的PbS纳米棒束,并初步探讨了其形成机理.     

Synthesis of uniform CoTe and NiTe semiconductor nanocluster wires through a novel coreduction method

A novel coreduction method was developed to synthesize uniform one-dimensional CoTe and NiTe nanocluster wires. In the synthesis, soluble Na(2)TeO(3) was used to supply a highly reactive Te source and N(2)H(4).H(2)O was used both as reducing agent and as complexing agent. The as-prepared samples were characterized by XRD, TEM, and HRTEM. The probable formation mechanism of the nanowires is discussed.     

Size-controlled synthesis and growth mechanism of monodisperse tellurium nanorods by a surfactant-assisted method

This article describes a surfactant-assisted approach to the size-controlled synthesis of uniform nanorods of trigonal tellurium (t-Te). These nanorods were grown from a colloidal dispersion of amorphous Te (a-Te) and t-Te nanoparticles at room temperature, which was first formed through the reduction of (NH4)2TeS4 by Na2SO3 in aqueous solution at 80 degrees C. Nuclei formed in the reduction process had a strong tendency to grow along the [001] direction due to the inherently anisotropic structure of t-Te. The formation of Te nanorods could be ascribed to the confined growth through the surfactant adsorbing on the surfaces of the growing Te particles. By employing various surfactants in the synthesis system, Te nanorods with well-controlled diameters and lengths could be reproducibly produced by this method. Both the diameters and lengths of nanorods decreased with the increase of the alkyl length and the polarity of the surfactants. Te nanorods could also be obtained in mixed surfactants, where the different surfactants were used to selectively control the growth rates of different crystal planes. We also observed that the as-synthesized nanorods with uniform size could be self-assembled into large-area smecticlike arrays.     

Interface characterization of nickel contacts to bulk bismuth tellurium selenide

Transmission electron microscopy (TEM) characterization of nickel contacts to bulk bismuth tellurium selenide [Bi₂(Te,Se)₃] is reported. Samples were prepared in a dual column focused ion beam/scanning electron microscope (FIB/SEM) system using a lift‐out technique, with ion beam energy and exposure times carefully optimized to minimize sample damage. Diffusion of Ni into Bi₂(Te,Se)₃ was observed and the formation of a nickel telluride (NiTe) interfacial region confirmed after heat treatment at 200 °C. Selected area diffraction patterns provided evidence of a modified bismuth telluride–like structure at the interface, identified by analytical electron microscopy to be composed of Ni and Bi₂(Te,Se)₃. Copyright © 2009 John Wiley & Sons, Ltd.     

用于高性能超级电容器的“三明治”结构Co9S8/NiTe/Ni的设计与合成

首先采用乙醇胺-氢氧化钾体系,实现了在泡沫镍表面原位生长NiTe活性物质层,随后以此为基体,通过复合Co9S8活性物质,构建出具有“三明治”结构、高容量、高循环稳定性的Co9S8/NiTe/Ni复合电极材料。该电极不仅在2 A·g^-1电流密度下表现出1890 F·g^-1的比电容,而且在大电流密度下依然表现出优异的稳定性。     

Inducing growth of FeNi-Pt match-like magnetic nanoheterostructures on Pt nanotips and dechlorination of hydrochloric ether

Newly designed magnetic FeNi-Pt match-like heterostructured nanorods were synthesized by means of induced growth of FeNi nanorods on Pt nanotips. The proposed synthesis mechanism is corroborated by SEM, TEM, XRD and XPS. The magnetic behavior shows that the magnetic saturation and coercivity are strongly dependent on both the shape and the alloy composition. The saturation magnetizations (Ms) and the coercivity (Hc) of nanorods synthesized are larger than those of nanoparticles because of the relatively large anisotropy of nanorods. Maximum saturation magnetization is obtained for Fe(82) Ni(15) -Pt(3) at 226.6 emu g(-1), whereas maximum coercivity is obtained for Fe(20)Ni(77)-Pt(3) at 136.8 Oe. Shape-dependent reactivity toward the reduction of chlorinated solvents was observed for the FeNi-Pt heterostructured nanomaterials. In particular, the Fe(82)Ni(15)-Pt(3) nanorods are highly reactive in the dechlorination process of 1,1,2,2-tetrachloroethane.     

Influence of EDTA on the hydrothermal synthesis of CdTe nanocrystallites

Transformation from Te nanorods to CdTe nanoparticles was achieved with the assistance of EDTA as a ligand under hydrothermal conditions. Experimental results showed that at the beginning of reaction Te nucleated and grew into nanorods. With the proceeding of reaction, CdTe nucleus began to emerge on the surface, especially on the tips of Te nanorods. Finally, nearly monodispersed hexagonal CdTe nanoparticles with diameters of about 200 nm were obtained. The effects of EDTA on the morphology and formation of CdTe nanoparticles were discussed in consideration of the strong ligand-effect of EDTA, which greatly decreased the concentration of Cd²⁺. Furthermore, the possible formation process of CdTe nanoparticles from Te nanorods was further proposed. The crystal structure and morphology of the products were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM).     

Nanostructure Synthesis at the Solid–Water Interface: Spontaneous Assembly and Chemical Transformations of Tellurium Nanorods

Bottom‐up synthesis offers novel routes to obtain nanostructures for nanotechnology applications. Most self‐assembly processes are carried out in three dimensions (i.e. solutions); however, the large majority of nanostructure‐based devices function in two dimensions (i.e. on surfaces). Accordingly, an essential and often cumbersome step in bottom‐up applications involves harvesting and transferring the synthesized nanostructures from the solution onto target surfaces. We demonstrate a simple strategy for the synthesis and chemical transformation of tellurium nanorods, which is carried out directly at the solid–solution interface. The technique involves binding the nanorod precursors onto amine‐functionalized surfaces, followed by in situ crystallization/oxidation. We show that the surface‐anchored tellurium nanorods can be further transformed in situ into Ag₂Te, Cu₂Te, and SERS‐active Au–Te nanorods. This new approach offers a way to construct functional nanostructures directly on surfaces.     

One‐pot Synthesis and Characterization of Gold‐nickel Bimetallic Nanorods

This report focuses on the synthesis of gold‐nickel bimetallic nanostructures. In the presence of amine as the capping agent, thermal decomposition of organometallic precursors CH₃AuPPh₃ and Ni(PPh₃)₄ in o‐xylene offered AuNi nanorods. Several preparative parameters possible influencing the morphology of the structure were carefully studied by varying the reaction conditions with respect to the standard procedure. The morphology and composition of the AuNi nanorods were principally characterized by transmission electron microscopy, energy dispersive spectroscopy, and powder X‐ray diffraction. The distribution of the Au as well as Ni atoms was examined by EDS mapping analysis. The mechanism of the formation of the AuNi bimetallic nanorods is proposed on the base of observation of the morphologies of nanostructures at various reaction time intervals.     

氢氧化镍纳米棒的水热制备及其表征

以Ni₂SO₄·6H₂O和NaOH为原料,在水热条件下制备了氢氧化镍纳米棒.运用透射电子显微镜(TEM)和X射线衍射仪(XRD)对样品进行了表征,考察了水热反应温度和pH值对产物的形貌和结构的影响.结果表明,氢氧化镍纳米棒形成的最佳条件是180～200℃,pH为9～10.     

Ba2NiTeO6 – eine neue Verbindung in der Reihe der hexagonalen Perowskite

Ba₂NiTeO₆ — a novel compound in the series of hexagonal perovskites (Ba₂)(¹²)(NiTe)(⁶)O₆ crystallizes in the rhombohedral space group R3 m with a = 5.797 and c = 28.595 Å for the unit cell in the trigonal setting, which contains 6 formula units. The crystal structure was solved by single crystal X-ray diffraction and refined down to R = 2.9%. It can be described by 12 close-packed BaO₃ layers alternating in the sequence hhcchhcc…, with an ordered occupation of the octahedral lattice sites by Ni and Te atoms. Groups of three octahedra, which are connected with one another by common faces, are linked with each other by TeO₆ octahedra via common corners. The central octahedra of these face-linked groups are occupied by Te, the outer ones by Ni. The bonding within the NiO₆ polyhedra is discussed on the basis of the ligand field spectra and compared to similar compounds. It is shown that there can be an appreciable change of the ligand field parameter Δ (30%) even when the Ni — O distances are nearly equal — in contrast to the predictions of the crystal field theory. Effects of this kind are observed under certain structural conditions, when the bonding within the NiO₆ polyhedra is changed indirectly by substitution of atoms with a noble gas configuration (W⁶⁺) by atoms with a d¹⁰-configuration (Te⁶⁺) in the cationic environment of Ni²⁺.