表面活性剂辅助室温液相合成BaCO3纳米棒

用阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)为形貌控制剂,通过室温液相反应成功制备出BaCO3纳米棒.纳米棒的直径为60～250nm、长度达几微米.用X射线粉末衍射和透射显微镜技术对所制备纳米晶的成分、形状和尺寸进行了表征分析.研究结果表明,表面活性剂对BaCO~纳米棒的形成起着关键的作用.对BaCO~纳米棒的形成机理作了深入的讨论,提出了BaCO3纳米棒的表面活性剂软模板诱导自组装生长机理.     

表面活性剂辅助低温固相合成CuS纳米棒

用表面活性剂聚乙二醇400为形貌控制剂,通过低温固相反应成功制备出CuS纳米棒.纳米棒的直径为10～60 nm、长度为100～600 nm.研究结果表明,在反应过程中,表面活性剂所形成的结构对最终纳米晶的形貌起着决定性的作用.用X射线粉末衍射和透射显微镜技术对所制备纳米晶的成分、形状和尺寸进行了表征分析.对CuS纳米棒的形成机理作了深入的讨论,提出了CuS纳米棒的表面活性剂软模板诱导自组装生长机理.     

钴纳米棒的有机相化学还原法制备及其表征

在有机相中,表面活性剂聚乙烯吡咯烷酮(PVP)存在下,采用联氨还原氯化钴的化学方法制备得到钴纳米棒,并用XRD、TEM、XPS和TG-DTA对样品的组成和形貌进行表征和分析.结果表明,用该法制得的钴纳米棒直径约为50～80m,长度约为300～500 nm,具有hcp相.表面活性剂PVP在钴纳米棒的形成过程中起到软模板的作用,使钴纳米粒子沿着一定的方向生长成纳米棒.     

水合肼还原法制备钴纳米棒

以表面活性剂聚乙烯吡咯烷酮（PVP）为软模板，采用水合肼作还原剂还原钴盐制备出钴纳米棒，通过XRD、XPS、TEM等分析手段对其结构和形貌进行了表征。结果表明：这种方法制备出来的钴纳米棒长度约为3-4μm，直径约为70～100nm，具有hcp晶相和fcc晶相，其含量比例约为1：1。     

ZnO纳米棒的低温湿化学制备

在低温反应条件下,通过超声的方法,以DBS作为表面活性剂,制备了ZnO纳米棒。化学反应的低温条件由冰水浴提供,温度为0~5℃。扫描电子显微镜和光学显微镜观察表明,所制备的纳米棒形状均一,截面为六方型,直径100nm,长度1μm; X 射线衍射表征指出所得到的纳米棒为六方晶型。同时,我们也研究了反应温度、表面活性剂含量、超声、回流时间对ZnO纳米棒形貌的影响。与其它制备方法相比,低温与超声技术可以更为方便获得分布均一,长径比较小的ZnO纳米棒。     

In2O3纳米棒的制备与表征

以非离子表面活性剂作为形貌控制剂，采用溶胶-凝胶法制备In2O3纳米棒前驱物，经500℃煅烧1h，成功制备了长约120nm，直径20nm的In2O3纳米棒。根据综合热分析（TG—DSC）结果，前驱体是In（OH）3部分脱水的In2O（OH）4干凝胶；计算表面活性剂分子的几何排列参数P在1／3～1／2之间，确定体系形成的是棒状胶团，并对其影响因素和机理进行了讨论。     

CTAB软模板法碳酸锶纳米棒制备

以六水氯化锶、氢氧化钠和尿素为原料,采用尿素水解均相沉淀法利用表面活性剂CTAB所形成的棒状胶束为软模板定向诱导制备出了晶形规整的碳酸锶纳米棒,利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对其进行了表征。结果表明,碳酸锶纳米棒呈规则的直线状,长度在6μm以上,平均粒径约80nm,长径比达到70以上。对碳酸锶纳米棒的形成机理进行了初步的研究,最后进一步讨论了CTAB用量对粒子形貌的影响情况。     

表面活性剂对超细BaTiO3纳米颗粒制备的影响

以钛酸四丁酯为钛源,醋酸钡为钡源,采用改进的水热法(即溶剂热法)在低温条件下合成钙钛矿结构的超细钛酸钡纳米颗粒,重点研究表面活性剂对产物的影响,探讨了不同表面活性剂影响产物形貌和种类的作用机理.通过扫描电子显微镜(SEM)、X射线衍射(XRD)及能谱(EDS)对产物进行表征,结果表明加入不同的表面活性剂时,制备的产物不同,其产物的形貌分别为超细纳米线、纳米棒(直径约几十纳米)和纳米颗粒(尺寸约50～100nm).通过调节反应过程中的表面活性剂,可以实现从线状钡的硫酸盐到纯相的超细钛酸钡纳米颗粒的转变.此方法为尺寸小于20nm的钛酸钡颗粒的制备及铁电材料尺寸限制效应的研究提供了重要参考.     

微乳水热法制备单晶BaCO3纳米线

利用反相胶束结合溶剂热法制备了BaCO3单晶纳米线。该方法中,油酸／正辛烷／水体系中的反相胶柬起到模板作用,引导BaCO3沿一维方向生长,通过X射线衍射（XRD）、扫描电子显微镜（SEM）、投射电子显微镜（TEM）和高分辨电子显微镜（HRTEM）对BaCO3纳米线进行了表征,结果表明,所制备的BaCO3纳米线为均匀的直线形单晶纳米线,直径为80～200nm,长度为几百纳米到几微米。对BaCO3纳米线的形成机理进行了分析。     

针状纳米氢氧化镁的形貌控制

以氯化镁和氢氧化钠为反应物，添加表面活性剂十二烷基苯磺酸钠（SDBS），在水溶液中利用反向沉淀法制备针状纳米氢氧化镁粉体，其直径为9～12nm，长度为40～110nm。并应用X射线粉末衍射仪（XRD）、场发射扫描电子显微镜（FESEM）、高分辨透射电子显微镜（HRTEM）对所制备粉体的晶型结构、粒度、形貌进行表征。同时讨论了表面活性剂／分散剂对纳米氢氧化镁粉体形貌的影响。     

Hierarchical nanostructures of PbTiO3 through mesocrystal formation

Novel hierarchical self-assembled structures; bur-like PbTiO3 nanostructures were made by self-assembly of PbTiO3 nanocrystals under hydrothermal conditions using sodium dodecylbenzene sulfonate surfactant. The bur-like nanostructures exhibit a unique geometrical shape with cores of agglomerated nanocrystals and outershells of nanorods. The nanorods were between 30 nm and 100 nm in diameter and from several hundred nm up to 2 microm in length. We demonstrate that these nanostructures are formed in a two step process where agglomeration of PbTiO3 nanoparticles into microspheres occurs in a first step, followed by assembly of cube-shaped nanoparticle building blocks into PbTiO3 mesocrystals in a second step. The mesocrystals continuously grow into nanorods from the surface of the microspheres acting as a substrate.     

Surfactant controlled synthesis of crystalline phosphovanadate nanorods

Phosphovanadate nanorods were obtained in a reaction of vanadium (V) oxide as a precursor and a cationic surfactant, dodecylpyridinium chloride, as structure directing template at pH ∼3 at room temperature. The composition and morphology of the nanorods was established by powder X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), fourier transform infra-red spectroscopy (FTIR), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The obtained nanorods have diameters of 40-60 nm with lengths up to 1 μm. The effect of reaction parameters such as concentration of surfactant and pH of the solution on the growth of nanorods has been investigated. A plausible mechanism involving the coalescence of nanoparticle ‘seeds’ leading to one-dimensional nanorods is also discussed. The same reaction when performed under hydrothermal condition, keeping other reaction parameters unchanged, resulted in the formation of phosphovanadate nanospheres of diameter 10-15 nm.     

Facile route to the synthesis of porous α-Fe2O3 nanorods

The requirements of simple and reliable protocols for the synthesis of anisotropic structures with controlled morphology continue to be a major challenge in nanoscience. In this paper we describe the facile synthesis of porous hematite (α-Fe₂O₃) nanorods using anionic surfactant as a rod-like template. α-FeOOH nanorods with diameters of 170–210 nm and lengths up to 3–5 μm were synthesized in high yield via hydrothermal method using sodium dodecyl sulphate as a template. The porous α-Fe₂O₃ was obtained after solvent extraction and calcining the as-obtained α-FeOOH nanorods at 500 °C for 6 h. Even after removal of template by solvent extraction and calcination the shape of the nanorods was intact except the generation of pores on the nanorods. The porous nanorods were analysed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission and high-resolution transmission electron microscopy (TEM & HRTEM), scanning electron microscopy (SEM) and superconducting quantum interference device (SQUID) measurements. SEM and TEM images showed that the morphology of hematite nanostructure is homogeneous in the shape of rods and full of porosity and magnetization measurements of the porous α-Fe₂O₃ nanorods showed weak ferromagnetic behavior. The surfactant SDS (sodium dodecyl sulphate) plays a key role in controlling the nucleation and growth of the nanorods and their use as a new class of inorganic scaffolds for the synthesis of nanomaterials are salient features of the work with implications in crystal engineering and nanocomposites design for various applications.     

Effect of suitable surfactant on the large scale preparation of WO3 nanorods for the synthesis of WS2 nanoparticles

WO3 nanorods with average dimension about 23 x 145 nm have been synthesized in gram quantities by a hydrothermal method. Effect of various surfactants on the WO3 nanorods morphology was investigated. The results demonstrated that the application of suitable surfactant (such as Triton X-100), leads to obtain obviously individual morphology for WO3 nanorods (with average dimensions about 15 x 100 nm) and decrease the reaction time from 7 days to 3 days. With a very suitable and safe method, the as-prepared WO3 nanorods, will turn to WS2 nanoparticles by mixing them with Sulfur (S) powder, under reducing H2 atmosphere and high temperature. Therefore, application of the harmful and poisonous H2S gas was eliminated.     

Ba0.8Sr0.2Ti0.5Mn0.5O3纳米晶体的合成及气敏性质研究

采用复合碱媒介法(CHM),在合成BaMnO3和Ba0.5Sr0.5MnO3的基础上,以Sr(NO3)2、BaCO3以及MnO2和TiO2为原料,在200℃、24h的生长条件下,用20%的Sr离子替代20%的Ba离子,用50%的Ti离子替代50%的Mn离子成功合成了Ba0.8Sr0.2Ti0.5Mn0.5O3纳米晶体。采用XRD、SEM及EDS对产物的晶相、形貌和成分进行了分析,对Ba0.8Sr0.2Ti0.5Mn0.5O3制作的电极进行了气敏性质的测定。     

原位生成法制备单分散的纳米氧化锌分散液

用ZnCl2作原料,PVP作分散剂,在160℃下采用原位生成法制得单分散、具有良好晶体结构和规则外形的ZnO纳米单晶分散液,用透射电子显微镜、X射线衍射、紫外/可见分光光度计等测试手段对其进行了表征.讨论了工艺条件对纳米ZnO尺寸和形貌的影响,并对其生长机理做了初步探讨.     

Superparamagnetic maghemite nanorods: analysis by coupling field-flow fractionation and small-angle X-ray scattering

We report on the online coupling of asymmetrical flow field-flow fractionation (A4F) with small-angle X-ray scattering (SAXS) for the detection of nanoparticles. The A4F was used to fractionate superparamagnetic maghemite nanoparticles, which were prepared continuously with a micromixer. The outlet of the A4F was directly coupled to a flow capillary of a SAXSess instrument (Kratky type of camera). SAXS curves were recorded in a 1 s time interval. This was possible by using intense synchrotron radiation. The radii of gyration of the nanoparticles, as determined from Guinier plots, increased from 2 to 6 nm with increasing fractionation time of the A4F. A more detailed analysis of the scattering curves revealed that the particles were cylindrical in shape (nanorods), which we attributed to the micromixing preparation technique. The radii of the nanorods increased only slightly from 1.2 to 1.7 nm with increasing fractionation time, while the lengths increased strongly from 7.0 to 30.0 nm. The volume distribution of the nanorods was determined and described by Schultz-Zimm and log-normal distributions. Nanorod volumes increased from 45 to 263 nm(3), corresponding to molar masses of 140 x 10(3) to 820 x 10(3) g mol(-1). We propose A4F-SAXS coupling as a new method for analysis of nanoparticles of complex composition in solution. It allows precise online determination of the particle's shape and size distributions. This method can be applied to mixtures of nanoparticles of arbitrary shapes and sizes (1-100 nm). Moreover, the total time needed for fractionation and online SAXS data recording is usually only 20 min.     

Sonochemical synthesis and shape change of colloidal CdSe nanocrystals by high-intensity ultrasound

In this article, we have developed the synthesis of CdSe nanocrystals by the introduction of high-intensity ultrasound combined with an anionic surfactant (sodium dodecyl sulfate, SDS). TEM, XRD, and SEM EDS confirmed the successful synthesis of CdSe nanoparticles with zinc blende crystal phase. UV, PL, and TEM revealed that large particles settled to the bottom of the reaction flask. In the lower part precipitate, nanorods of different aspect ratios were also observed. The CdSe nanorods were formed by self-assembly due to the SDS surfactant and high-intensity ultrasound. A three-stage mechanism for the synthesis of CdSe nanorods was proposed. The effect of SDS concentration on the shape of nanorods was also investigated. At medium concentrations of SDS (0.2 M), one-dimensional CdSe nanorods with different aspect ratios were obtained. When using low concentrations of SDS (0.1 M), two-dimensional square-like crystals were observed due to all growth crystal faces having roughly the same surface energy.     

One-step wet chemistry for preparation of magnetite nanorods

A magnetite with high aspect ratio has been synthesized by a wet chemical process. A surfactant, polyethylene glycol, was used as the template, and a ferrous ammonia sulphate was used as iron source. In the one-step synthesis, a suitable ratio between the rates of deposition and oxidation of ferrous ions was achieved by adjusting the diffusion of ammonia and resulted in the iron oxide deposited with nanorod morphology. According to X-ray powder diffraction analysis, these nanorods crystallize in structure of magnetite phase. Transition electron microscopy and selected area electron diffraction investigations have revealed that nanorods are single crystal and up to 2000 nm long and their diameters generally range from 20 to 100 nm. The measurement by vibration sample magnetization shows the magnetization of the as-synthesized nanorods is higher than 50 emu/g. The presented one-step synthesis approach provides an advantageous access to large quantity of this important anisotropic nanomaterial.