Yankuan Liu

University of Science and Technology of China, Hefei, Anhui Sheng, China

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Publications (18)18.29 Total impact

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    ABSTRACT: The concentration of the Mn(NO3)2 solution has significant influence on the morphologies and the phases of the MnO2 products. A large number of εε- MnO2 nanowires were prepared via a simple pyrolysis under lower reaction concentration. The nanowires have lengths up to tens of micrometers and diameters in the range of 20–100 nm. The ββ- MnO2 nanobundles and nanoflowers were prepared by increasing the concentration of Mn(NO3)2 solution. The superparamagnetism of εε- MnO2 nanowires and paramagnetism of ββ- MnO2 nanoflowers indicate their potential applications in magnetic materials.
    Solid State Communications 10/2009; 149(s 37–38):1514–1518. · 1.53 Impact Factor
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    ABSTRACT: Well-aligned arrays of cuprous oxide (Cu2O) nanowires were synthesized through the reduction of Cu(CH3COO)2 by ethylene glycol (EG) without the assistance of externally introduced template. The panorama of well-aligned arrays of Cu2O nanowires looks like a biscuit. These Cu2O nanowires are ∼30nm in diameter. A systematic investigation has been carried out to understand the factors influencing the phase composition and Cu2O morphologies.
    Materials Chemistry and Physics - MATER CHEM PHYS. 01/2009; 114(1):213-216.
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    ABSTRACT: Octopod-like PbSe structures with eight symmetric arms of 1.0−3.0 µm in length have been hydrothermally synthesized without any surfactant. Keeping the other conditions the same, only by changing the molar ratio of NaOH/Pb(NO3)2 from 40 to 5, quasi-spherical nanoparticles were obtained. As poly(vinyl pyrrolidone) (PVP) was added, single-crystal PbSe nanosheets of 20−60 nm in thickness and 0.5−5.0 µm in-plane sizes can be formed. Similarly, by changing the molar ratio of NaOH/Pb(NO3)2 from 40 to 5, the nanocubes of 70 nm in edge length were formed. The possible growth mechanisms for the nanosheets and octopod-like structures of PbSe are discussed on the basis of transmission electron microscopy and scanning electron microscopy analysis from the time-dependent experiments.
    Crystal Growth & Design - CRYST GROWTH DES. 03/2008; 8(4).
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    ABSTRACT: A solution route has been developed to synthesize covellite (CuS) nanostructures through the precitation reaction of CuCl2.2H2O, thiourea (Tu), and NaHCO3 in distilled water at room temperature. By regulating the concentration of Tu, CuS nanotubes and hollow nanospheres with diameters of 100-200 nm have been selectively prepared. Structural characterizations indicate that both nanotubes and hollow spheres are composed of CuS nanoparticles with diameters of about 5-10 nm. UV-Vis absorption and room temperature photoluminescence (PL) spectra display different morphology-related absorption phenomena for nanotubes and hollow nanospheres. A systematic investigation has been carried out to understand the factors influencing the CuS morphology. Two different routes are identified to explain the formation of the nanotubes and hollow nanospheres herein.
    Journal of Nanoscience and Nanotechnology 01/2008; 7(12):4501-7. · 1.15 Impact Factor
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    ABSTRACT: A series of β-NiS three-dimensional (3D) flowerlike architectures with an average diameter of 2−4 μm have been hydrothermally synthesized in the presence of ammonia and trisodium citrate. Morphology modification can be conveniently realized by varying the reaction temperature. At 120 °C the flowerlike architectures were composed of nanoneedles. At 180 °C the flowerlike architectures were composed of nanorods, while mixtures of nanoneedle-based and nanorod-based flowerlike architectures were obtained in the temperature range of 140−160 °C. Citrate anion was introduced as both a coordinating reagent and a shape modifier to control the anisotropic growth of β-NiS. Besides a probable growth mechanism, the citrate-assisted Ostwald ripening process was proposed to explain the formation of flowerlike architectures on the basis of transmission electron microscopy observations. Such a simple and mild synthetic route may be extended to fabricate complex 3D architectures of other materials.
    Crystal Growth & Design - CRYST GROWTH DES. 08/2007; 7(9).
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
    Berichte der deutschen chemischen Gesellschaft 07/2007; 2007(28):4508 - 4513. · 2.94 Impact Factor
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    ABSTRACT: Silver nanoparticles were synthesized by gamma-ray irradiation of acetic water solutions containing AgNO3 and chitosan. The resulting particles with the average diameter of 4 5 nm were densely dispersed in the solution due to the protection of chitosan chains. UV vis spectra showed that the irradiation dose would affect the size distribution of nanoparticles.
    Radiation Physics and Chemistry 07/2007; 76:1165-1168. · 1.38 Impact Factor
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    ABSTRACT: A new inorganic/organic (I/O) nanocomposite (ZnS/NaSCH2COONa) with a ribbon-like structure was synthesized by using Zn(NO3)27H2O and thioglycolic acid as reactants under hydrothermal conditions at 160 °C. SEM, TEM, XRD, XPS, IR and XAFS were used to characterize and analyse the morphology, microstructure and formation mechanism of the new I/O composite material. The ZnS nanocrystals are about 4.5 nm in diameter and distribute in the nanoribbons uniformly. The ZnS/NaSCH2COONa nanoribbons would decompose into nearly monodispersed wurtzite ZnS sphere-like nanostructures with a diameter of about 300 nm through hydrothermal treatment. Photoluminescence (PL) was used to study the optical properties of ZnS/NaSCH2COONa nanoribbons. Compared with the wurtzite ZnS sphere-like nanostructures, the I/O composite nanoribbons presented a greatly enhanced light emission at 425 nm, which indicates their potential applications in luminescence materials.
    Nanotechnology 06/2007; 18(28):285605. · 3.84 Impact Factor
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    ABSTRACT: A solution-phase route has been developed for the synthesis of single-crystal CuO nanoribbons with widths of 10−80 nm, thicknesses of 5−20 nm, and lengths ranging from several hundred nanometers to several micrometers and for nanorings with diameters of 100−300 nm. The CuO nanoribbons and nanorings were fabricated by the reaction of CuCl2 and NaOH solutions with sodium dodecyl benzenesulfonate (SDBS). The as-synthesized products were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM), revealing that CuO nanoribbons and nanorings had single-crystal monoclinic structures and nanorings were closed but were not the simple superposition of two ends of the nanoribbons. On the basis of TEM observations, the formation processes of nanoribbons and nanorings can be interpreted by two stages:  initial nanoflakes split into nanoribbons due to the Brownian movement of surfactant molecules, and then these nanoribbons that possess polar surfaces coil into nanorings to reduce the electrostatic energy. This ringlike CuO nanomaterial may have some potential value in nanoscale applications.
    Crystal Growth & Design - CRYST GROWTH DES. 04/2007; 7(5).
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    ABSTRACT: Uniform submicron hydrogenated amorphous carbon “test tubes”, both empty and containing nickel particles, were synthesized via the self-catalysis-decomposition of Ni(Hdmg)2 (Hdmg = dimethylglyoxime anion) at 250 °C. Since one end of the tubular carbon is always open but the other end is closed, they look like “test tubes”. Transmission electron microscopy images show they have an average inner (outer) diameter of 560 nm (740 nm) and an average length of around 5.4 μm. They were characterized by X-ray diffraction, scanning and transmission electron microscopy, energy-dispersive X-ray analysis, Fourier transform infrared spectroscopy, Raman spectroscopy and thermogravimetric analysis. The results indicated that the “test tubes” consist of amorphous hydrogenated carbon. The magnetic properties of the contained nickel reached a coercivity as high as Hc ≈ 153 Oe and showed a remarkable decrease of saturation magnetization. The reaction temperature and solvent are of great importance in determining the final structures. A possible formation mechanism was discussed.
    Carbon. 01/2007; 45(7):1571-1577.
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    ABSTRACT: Copper microstructures assembled with nanowalls have been synthesized in aqueous solution at 200 °C for 24 h. Two different novel morphologies, microstructures with net and radial shapes, were obtained by controlling the concentration of the starting materials. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) technologies. The formation mechanism of the morphology control over the copper microstructures was investigated; the addition of NaOH in aqueous solution and the choice of NaH2PO2·H2O as the reducing agent were found to be important for the final generation of copper microstructures.
    Crystal Growth & Design - CRYST GROWTH DES. 10/2006; 6(11).
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    ABSTRACT: In this paper, a green chemical synthetic route was developed to synthesize single-crystalline Te nanowires with an average diameter of 7 nm at a low temperature (90 °C) by using ascorbic acid as a reducing agent, Na2TeO3 as a tellurium source, and surfactant cetyltrimethylammonium bromide (CTAB) as a structure-directing agent. The morphology of Te nanowires in the presence of CTAB is strongly dependent on the reaction conditions such as the concentration of CTAB, reaction time, and reducing agents. A surfactant-assisted solid−solution−solid growth mechanism was identified to explain the formation of ultrathin Te nanowires. The single-crystalline Te nanowires with an average diameter of 7 nm display strong luminescence emission in the blue-violet region.
    Crystal Growth & Design - CRYST GROWTH DES. 10/2006; 6(11).
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    ABSTRACT: In this article, a novel magnesium-catalyzed co-reduction route was developed for the large-scale synthesis of aligned beta-SiC one-dimensional (1D) nanostructures at relative lower temperature (600 degrees C). By carefully controlling the reagent concentrations, we could synthesize beta-SiC rodlike and needlelike nanostructures. The possible growth mechanism of the as-synthesized beta-SiC 1D nanostructures has been investigated. The structure and morphology of the as-synthesized beta-SiC nanostructures are characterized using X-ray diffraction, Fourier transform infrared absorption, and scanning and transmission electron microscopes. Raman and photoluminescence properties are also investigated at room temperature. The as-synthesized beta-SiC nanostructures exhibit strong shape-dependent field emission properties. Corresponding to their shapes, the as-synthesized nanorods and nanoneedles display the turn-on fields of 12, 8.4, and 1.8 V/microm, respectively.
    The Journal of Physical Chemistry B 08/2006; 110(29):14172-8. · 3.61 Impact Factor
  • Chemistry Letters - CHEM LETT. 01/2006; 35(8):898-899.
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    ABSTRACT: Polymorph discrimination of CaCO3 mineral has been easily realized in an ethanol/water mixed solution system under mild conditions without using any organic additives. The phase transition from a mixture of calcite and aragonite to pure aragonite, and then to almost pure vaterite, can be nicely captured by the choice of a suitable ratio of ethanol to distilled water in the present reaction system. In addition, a complex self-assembly process for the formation of multilayered vaterite cakes in this binary solution system has been proposed. The cakelike vaterite crystals with multilayered structures are porous with an average pore size of 24.9 nm. The results demonstrated that such a binary reaction media could provide an alternative and versatile tool for controlling the polymorph and nanostructures of inorganic minerals through manipulating the thermodynamics and kinetics. This study provides an alternative polymorph switching route for CaCO3 mineral without using any additives and can even be scaled up as a green chemistry method for the industrial production of CaCO3 with different polymorphs.
    ChemInform 12/2005; 18(1).
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    ABSTRACT: A new and efficient Tx-100/cyclohexanol/H2O micellar system has been developed to synthesize rectangular single-crystalline PbCrO4 nanotubes and nanorods through a self-seeding template growth (SSTG) process at room temperature. Studies found that the whole procedure involves the nucleation of nanoparticles, the growth into nanotubes from nanoparticles and the evolution into nanorods from nanotubes, merely by stepwise prolonging the reaction time while keeping other conditions constant. This simple method provides guidance for the morphology control of other nanostructural materials.
    Nanotechnology 09/2005; 16(11):2619. · 3.84 Impact Factor
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    ABSTRACT: The multi-armed CdS architectures can be synthesized from the reaction of the anhydrous CdCl2 and sulfur powders in ethylenediamine, in which a simple one-step reactant–solvent synchronous (RSS) co-assisted effect was proposed to be responsible to the growth of the multi-armed structures. The as-prepared products were characterized by XRD, XPS and TEM. In addition, their optical properties were also shown by UV–vis and fluorescence spectrum. FT-IR spectrum indicated that the dissociation of ethylenediamine molecule absorbed on the surface of CdS resulted in the formation of intermediate CdS(en)m−n cores and thus provided the condition for the anisotropy growth of CdS. The present technique may give a clue to grow the one-dimensional nano-sized semiconductors by the proper choice of the reactant and the solvent.
    Materials Research Bulletin. 01/2005; 40(12):2180-2188.
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    ABSTRACT: For Abstract see ChemInform Abstract in Full Text.
    ChemInform 09/2003; 32(5):426-427.