Synthesis and photoluminescence of Y2O3:RE3+ (RE=Eu, Tb, Dy) porous nanotubes templated by carbon nanotubes

Y2O3:RE3+(RE=Eu, Tb, Dy) porous nanotubes were first synthesized using carbon nanotubes as template. The morphology of the coated precursors and porous Y2O3:Eu3+ nanotubes was determined by scanning electron Microscopy (SEM) and transmission electron microscopy (TEM). It was found that the coating of precursors on carbon nanotubes (CNTs) is continuous and the thickness is about 15 nm, after calcinated, the Y2O3:Eu3+ nanotubes are porous with the diameter size in the range of 50-80 nm and the length in micrometer scale. X-ray diffraction (XRD) patterns confirmed that the samples are cubic phase Y2O3 and the photoluminescence studies showed that the porous rare earth ions doped nanotubes possess characteristic emission of Eu3+, Tb3+, and Dy3+. This method may also provide a novel approach to produce other inorganic porous nanotubes used in catalyst and sensors.     

Characterization of Bi2S3 with different morphologies synthesized using microwave radiation

Bi₂S₃ with different morphologies (nanoparticles, nanorods and nanotubes) was synthesized using bismuth nitrate pentahydrate (Bi(NO₃)₃·5H₂O) and two kinds of sulfur sources (CH₃CSNH₂ and NH₂CSNH₂) in different solvents (water, ethylene glycol and propylene glycol) via a microwave radiation method at 180 W for 20 min. X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that all of the products are orthorhombic Bi₂S₃ phase of nanoparticles, nanorods and nanotubes, influenced by the sulfur sources and solvents. Formation mechanisms of the products with different morphologies are also proposed.     

Synthesis of flower-like CuS nanostructured microspheres using poly(ethylene glycol) 200 as solvent

CuS flower-like microspheres with the diameter of about 3-4 microm constructed by nanoflakes with thickness of about 30-40 nm have been successfully synthesized by a simple wet chemical method. In this reaction system, Poly(ethylene glycol) 200 (PEG 200) was used as solvent, CuCl2 2H2O as cuprum source, and thioacetamide (TAA) as sulfur source. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) in detail. The XRD patterns revealed that the products were pure hexagonal phase of CuS. Experiments with various parameters indicated that the reaction temperature and molar ratio of CuCl2 2H2O to thioacetamide had strong effects on the sizes and morphologies of CuS crystals. A possible growth mechanism on the formation of CuS microspheres was proposed. The PEG 200 acted as solvent, complexing agent, and soft template in this synthesis. Furthermore, optical studies of the products including UV-Vis absorption spectrum and photoluminescence spectrum have also been carried out.     

A simple route to synthesis of BaCO3 nanostructures in water/ethylene glycol mixed solvents

Barium carbonate (BaCO₃) nanostructures with different morphologies were synthesized using Ba(NO₃)₂ and (NH₄)₂CO₃ in the water/ethylene glycol (EG) mixed solvents by oil bath heating at 80 °C for 30 min. The molar ratio of water to EG had an effect on the morphology of BaCO₃. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM).     

Synthesis of single-crystalline Ce(CO3)(OH) with novel dendrite morphology and their thermal conversion to CeO2

Single-crystalline cerium carbonate hydroxide (Ce(CO₃)(OH)) with dendrite morphologies have been successfully synthesized by hydrothermal method at 150 °C using Ce(NO₃)₃·6H₂O as the cerium source, aqueous carbamide as both an alkaline and carbon source and poly(vinyl pyrrolidone) (PVP) as surfactant. Ceria (CeO₂) with dendrite morphologies have been fabricated by a thermal decomposition-oxidation process at 500 °C for 6 h using single-crystalline Ce(CO₃)(OH) dendrites as the precursor. The dendrite morphologies of Ce(CO₃)(OH) was sustained after thermal decomposition-oxidation to CeO₂. The as-prepared products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), and thermogravimetric analysis (TG).     

CuS nanotubes prepared using Cu(OH)2 nanowires as self-sacrificial template

Copper sulfide (CuS) nanotubes assembled with nanoparticles have been successfully synthesized by microwave-assisted solvothermal method at 80 °C using Cu(OH)₂ nanowires in the solvent of ethylene glycol. Cu(OH)₂ nanowires act as both the precursor and template for the preparation of CuS nanotubes assembled with nanoparticles. Cu(OH)₂ nanowires are prepared by adding an aqueous solution containing CuCl₂ into an alkaline solution at room temperature and by ultrasonication for 30 min. This method has the advantages of the simplicity and low cost. The samples are characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The method reported herein may be extended to the synthesis of nanotubes of other copper-containing compounds.     

电泳沉积法制备钛酸纳米管膜层

采用水热合成法制备钛酸钠纳米管,然后依次与HNO3,正四丁基氢氧化铵水溶液(TBAOH)离子交换后,经过高速离心,将所得沉淀物分散于无水乙醇溶液中,并应用电泳沉积的方法成功地在不锈钢或导电玻璃表面构筑了钛酸纳米管薄膜.采用TEM、XRD、SEM及EDS等对纳米管薄膜的表面形貌、结构和组成等进行表征.结果表明,电泳沉积法制备钛酸纳米管薄膜致密均匀、厚度可控并与基体结合力良好;经高温烧结后,形貌基本保持不变,可望成为一种新的功能材料.文中还对纳米管薄膜的形成机理进行了讨论.     

Template-free synthesis of alpha-Fe2O3 hollow spindles

Alpha-Fe2O3 hollow spindles was synthesized via a one-step hydrothermal treatment via a poly(ethylene glycol) (PEG)-precursor route. Through controlling temperature, reaction time and the concentration of NaOH, we could get sphere, cubic, solid spindle and hollow spindle-like alpha-Fe2O3. The samples were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The magnetic research shows, the shape of the alpha-Fe2O3 nanostructure is important to their magnetic property. When the novel hollow spindle-like alpha-Fe2O3 was used as the photocatalytic material, they performed better than the solid structures.     

聚乙二醇法在温和条件下制备不同结构的磁性Fe3O4纳米晶

以Fe（acac）3为原料,乙二醇、聚乙二醇1000和聚乙二醇5000为还原剂和溶剂,在温和的溶剂热的条件下制备了不同尺寸的顺磁性Fe3O4纳米颗粒.利用X射线衍射（XRD）、光电子能谱（XPS）、透射电子显微镜（TEM）和磁性测量技术对制备的Fe3O4纳米颗粒的结构、形貌、磁性能进行了表征测试.结果发现,聚乙二醇分子链的长度对Fe3O4纳米颗粒的平均粒径大小、结晶度和饱和磁化强度均有重要影响.以乙二醇、聚乙二醇1000和聚乙二醇5000为还原剂制备的Fe3O4纳米颗粒的尺寸分别为2～3nm、5nm和7～8nm;相应的纳米Fe3O4颗粒饱和磁化强度分别为55.2、61.5和81.3emu/g;同时结晶度也随分子链的增加而增加.随分子链长度的增加,还原剂还原性的逐渐增加是导致Fe3O4纳米颗粒平均粒径大小、结晶度和饱和磁化强度逐渐增大的重要因素.     

Ni12P5微球的溶剂热合成与表征

以硫酸镍(NiSO4.7H2O)作为镍源,以乙二醇和水作为混合溶剂,利用溶剂热法成功地制备了磷化镍(Ni12P5)微球。X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、透射电镜(TEM)和高分辨透射电镜(HRTEM)等分别对所制备样品进行了表征。结果表明,所得产物为纯的四方相磷化镍(Ni12P5)微球,粒径约为2～5μm;研究了不同实验参数对样品尺寸、形貌及微球形成过程等的影响。最后对磷化镍微球的发光性进行了研究。     

Fabrication of three-dimensional snowflake-like bismuth sulfide nanostructures by simple refluxing

Three-dimensional snowflake-like bismuth sulfide nanostructures were successfully synthesized by simple refluxing at 160 °C in ethylene glycol, using bismuth citrate and thiourea as reactants. The crystal structures and morphologies of the products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDX). The Bi₂S₃ nanostructure was built up by highly ordered one-dimensional Bi₂S₃ nanorods, which was aligned in an orderly fashion. Ethylene glycol plays a critical role in the creation of bismuth sulfide three-dimensional nanostructures, which serves as an excellent solvent and structure director. Bismuth citrate, a linear polymer, also makes for the formation of the three-dimensional nanostructures.     

CuS:Ni flowerlike morphologies synthesized by the solvothermal route

CuS:Ni flowerlike morphologies composed of nanosheets were fabricated by the solvothermal route with polyvinyl pyrrolidon as surfactant and ethylene glycol as solvent. The as-prepared CuS:Ni morphologies were characterized by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The size of CuS:Ni flowerlike morphologies was about 2 and 5 μm corresponding to the Ni doping concentration of 3.7 and 7.1 at.%, respectively. The thickness of the nanosheets changes with changing Ni doping. The magnetic properties of the CuS:Ni products have been investigated in detail.     

化学还原法合成均匀银纳米线的条件研究

采用化学还原法,以乙二醇为还原剂,聚乙烯砒咯烷酮(PVP K30)为表面活性剂,通过还原硝酸银(AgNO3)溶液直接制备了高浓度的Ag纳米线溶液,并研究了PVP与AgNO3溶液摩尔浓度比和AgNO3溶液浓度对Ag纳米线生长的影响.用扫描电子显微镜(SEM)和透射电子显微镜(TEM)对纳米Ag晶体的生长形貌进行了比较,利...     

Shape-controlled synthesis of cobalt-based nanocubes, nanodiscs, and nanoflowers and their comparative lithium-storage properties

Facile hydrothermal methods have been developed to synthesize large Co3O4 nanocubes, β-Co(OH)2 hexagonal nanodiscs and nanoflowers. Samples are thoroughly characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller method, and thermogravimetric analysis. The Co3O4 nanocubes have an average size of about 350 nm with a perfect cubic shape, and the β-Co(OH)2 nanodiscs are uniform hexagonal platelets, whereas the β-Co(OH)2 nanoflowers are assembled from large sheetlike subunits. After thermal annealing in air at a moderate temperature, the as-prepared β-Co(OH)2 samples can be converted into spinel Co3O4 without significant alterations in morphology. We have also investigated the comparative lithium storage properties of these three Co3O4 samples with distinct morphologies. The nanoflower sample shows highly reversible lithium storage capability after 100 charge-discharge cycles.     

Repeatable synthesis of Cu2O nanorods by a simple and novel reduction route

Cu₂O nanorods were synthesized by reducing bamboo leaf-shaped Cu(OH)₂ with sodium hypophosphite (NaH₂PO₂) in an H₂O/ethylene glycol (EG) mixing solution. The Cu(OH)₂ was prepared by adding an alkaline solution to an aqueous solution containing CuSO₄ and NaH₂PO₂ at room temperature. The optimum temperature range for the reduction of the Cu(OH)₂ to Cu₂O nanorods was 55-70 °C. The products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The result showed the prepared Cu₂O nanorods were uniform and had diameters of 10-20 nm and lengths of 150-200 nm. The synthesis is simple, inexpensive, and highly repeatable.     

溶剂热制备花状ZnO纳米晶及光性能表征

利用溶剂热法,以乙酸锌（Zn（CH3COO）2·2H2O）和氢氧化钠（NaOH）为源,在乙二醇和水的混合溶剂中制备出了花状氧化锌纳米晶体,用X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）和选区电子衍射（SAED）测试分析,发现样品为六方纤锌矿结构的ZnO单晶,花状晶体的大小约为600nm,单个花瓣的长、宽分别约为300nm、100nm。对比实验发现,产物形貌对NaOH浓度的依赖性很大。紫外可见吸收光谱（UV—vis spectra）显示,产物除了本征吸收外,在长波方向（600nm处）也有一宽化的、较强的吸收峰。室温荧光光谱（PL spectra）显示,产物在400—480nm有一明显的发光带,且在405nm和472nm处有两个较强的发光峰。     

Growth and characterization of bamboo-like multiwalled carbon nanotubes over Cu/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalyst

The growth of bamboo-like multiwalled carbon nanotubes (MWCNTs) over Cu/Al₂O₃ catalyst by chemical vapor deposition under atmospheric pressure using ethanol as the carbon source has been demonstrated. The obtained MWCNTs are dominant with bamboo-like morphology. The morphologies, graphitization degree, and microstructures of the products were characterized by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and selected area electron diffraction. The results show that the combination of Cu/Al₂O₃ catalyst and ethanol was critical for the growth of bamboo-like MWCNTs. The possible factors causing the formation of bamboo-like structures were also discussed.     

Sonochemical synthesis of luminescent CeCO3OH one-dimensional quadrangular prisms

Orthorhombic single-crystalline cerium carbonate hydroxide (CeCO₃OH) with one-dimensional (1D) microstructures has been successfully synthesized by a facile sonochemical reaction between cerous nitrate and urea. These 1D microstructures were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM). The as-synthesized CeCO₃OH has uniform lengths and good dispersion. Synthetic parameters, such as the concentration of reagents, were found to have close relationship with the morphologies and sizes of the final products. The ultrasound-induced oriented attachment growth mechanism has been proposed for the possible formation mechanism of sample. Room-temperature photoluminescence of CeCO₃OH samples with different morphologies has also been investigated.     

Rapid synthesis of Bi2S3 nanocrystals with different morphologies by microwave heating

Single-crystalline Bi₂S₃ nanocrystals with urchinlike and rod-like morphologies have been successfully synthesized using Bi₂O₃, HCl, Na₂S₂O₃ and ethylene glycol (EG) by a simple and fast microwave heating method. Both urchinlike and rod-like Bi₂S₃ nanostructures could be formed under microwave heating at 190 °C for 30 s. Urchin-like Bi₂S₃ nanostructures were prepared using sodium dodecyl sulfate (SDS) or in the absence of any surfactant. However, Bi₂S₃ nanorods were obtained in the presence of cetyltrimethylammonium bromide (CTAB). The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), electron diffraction (ED) and ultraviolet-visible (UV-Vis) absorption spectra.     

White light emission from spin coated Gd2O3:Dy nano phosphors synthesized using polyol technique

Water dispersible Gd2O3:Dy3+ (2%) nanophosphors were synthesized through a facile polyol process and characterized by using X-ray diffraction (XRD), transmission electron microscopy (TEM), Dynamic Light Scattering (DLS) and photoluminescence (PL) spectrophotometry. The results of XRD, TEM and DLS show that resultant nanoparticles are single phasic and have spherical shape with 17 to 22% dispersibility. An efficient energy transfer was observed from host to the dopant ions. Characteristic blue and yellow emissions from Dy3+ ions were observed. The CIE coordinates of the nanophosphor lie in the white light region of the chromaticity diagram. Spin coating of the nanophosphor was done on quartz substrate. Bright white luminescence of this film was observed under ultraviolet light with lamda exc = 310 nm.