Publications (17)82.19 Total impact
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Article: Monazite and Zircon Type LaVO4:Eu Nanocrystals – Synthesis, Luminescent Properties, and Spectroscopic Identification of the Eu3+ Sites
Berichte der deutschen chemischen Gesellschaft 04/2010; 2010(18):2626 - 2635. · 2.94 Impact Factor -
Article: Highly luminescent self-organized sub-2-nm EuOF nanowires.
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ABSTRACT: Monodisperse sub-2-nm EuOF nanowires were obtained by manipulating the fluorophilicity between crystalline seeds and capping surfactant molecules during the thermolysis of Eu(CF(3)COO)(3) in oleic acid (OA) and oleylamine (OM). The uniform EuOF nanowires can self-organize on substrates to form parallel aligned superstructures and display strong Eu(3+)red emissions with high quantum yields of 65% under the UV light excitations due to the presence of dense surface Eu(3+) sites in the ultrathin nanowires as well as the passivation of the surface defects by the capping ligands.Journal of the American Chemical Society 11/2009; 131(45):16364-5. · 9.91 Impact Factor -
Article: Uniform Alkaline Earth Fluoride Nanocrystals with Diverse Shapes Grown from Thermolysis of Metal Trifluoroacetates in Hot Surfactant Solutions
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ABSTRACT: Uniform alkaline earth metal fluoride MF2 (M = Mg, Ca, and Sr) nanocrystals with various shapes (tetragonal MgF2 nanoneedle-constructed 3D networks; cubic CaF2 nanoplates and nanopolyhedra; cubic SrF2 nanoplates and nanowires) have been synthesized from the thermolysis of alkaline earth metal trifluoroacetate (M(CF3COO)2) in hot surfactant solutions (oleic acid, oleylamine, and 1-octadecene). The MF2 nanocrystals were formed by the controlled fluorination of the M−O bond into the M−F bond at the nucleation stage and subsequent growth process. For phase-pure MF2 nanocrystals, the growth of shape-selective MF2 nanocrystals was likely due to the template direction of micellar structures formed by self-assembly of capping ligands and the so-called “Ostwald ripening” process. With the developed synthetic strategy, the uniform upconversion SrF2:Yb,Er and core/shell SrF2:Yb,Er@SrF2 nanocrystals were also obtained. The core/shell-structured nanocrystals exhibited enhanced emission intensity and saturation power with respect to their core counterparts, owing to the suppression of associated nonradiative decays.03/2009; -
Article: Large-scale synthesis of single-crystalline iron oxide magnetic nanorings.
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ABSTRACT: We present an innovative approach to the production of single-crystal iron oxide nanorings employing a solution-based route. Single-crystal hematite (alpha-Fe2O3) nanorings were synthesized using a double anion-assisted hydrothermal method (involving phosphate and sulfate ions), which can be divided into two stages: (1) formation of capsule-shaped alpha-Fe2O3 nanoparticles and (2) preferential dissolution along the long dimension of the elongated nanoparticles (the c axis of alpha-Fe2O3) to form nanorings. The shape of the nanorings is mainly regulated by the adsorption of phosphate ions on faces parallel to c axis of alpha-Fe2O3 during the nanocrystal growth, and the hollow structure is given by the preferential dissolution of the alpha-Fe2O3 along the c axis due to the strong coordination of the sulfate ions. By varying the ratios of phosphate and sulfate ions to ferric ions, we were able to control the size, morphology, and surface architecture to produce a variety of three-dimensional hollow nanostructures. These can then be converted to magnetite (Fe3O4) and maghemite (gamma-Fe2O3) by a reduction or reduction-oxidation process while preserving the same morphology. The structures and magnetic properties of these single-crystal alpha-Fe2O3, Fe3O4, and gamma-Fe2O3 nanorings were characterized by various analytical techniques. Employing off-axis electron holography, we observed the classical single-vortex magnetic state in the thin magnetite nanorings, while the thicker rings displayed an intriguing three-dimensional magnetic configuration. This work provides an easily scaled-up method for preparing tailor-made iron oxide nanorings that could meet the demands of a variety of applications ranging from medicine to magnetoelectronics.Journal of the American Chemical Society 12/2008; 130(50):16968-77. · 9.91 Impact Factor -
Article: Luminescence resonance energy transfer sensors based on the assemblies of oppositely charged lanthanide/gold nanoparticles in aqueous solution.
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ABSTRACT: This work demonstrates luminescence resonance energy transfer (LRET) sensors based on lanthanide-doped nanoparticles as donors (D) and gold nanoparticles as acceptors (A), combined through electrostatic interactions between the oppositely charged nanoparticles. Negatively charged lanthanide-doped nanoparticles, YVO(4):Eu and LaPO(4):Ce,Tb, with high luminescence quantum yield and good water-solubility, are synthesized through a polymer-assisted hydrothermal method. Positively charged polyhedral and spherical gold nanoparticles exhibit surface plasmon resonance (SPR) bands centered at 623 and 535 nm, respectively. These bands overlap well with the emission of the Eu(3+) and Tb(3+) ions within the lanthanide nanoparticles. Herein, the gold nanoparticles are synthesized through a seed-mediated cetyltrimethylammonium bromide (CTAB)-assisted method. The assemblies of the oppositely charged donors and acceptors are developed into LRET-based sensors exhibiting a donor quenching efficiency close to 100 %.Chemistry - An Asian Journal 09/2008; 3(10):1857-64. · 4.50 Impact Factor -
Article: Hierarchical Construction of ZnO Architectures Promoted by Heterogeneous Nucleation
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ABSTRACT: In this work, ZnO hierarchical architectures are successfully fabricated by concentration-controlled heterogeneous nucleation behavior through a one-pot solution method, free of organic structure-directing agents or pretreated substrates. A two-stage nucleation-growth process should account for the assembly process. First, the ZnO flowerlike plate aggregates formed with fast nucleation-growth kinetics. Then, these plate aggregates served as substrates to induce secondary heterogeneous nucleations under appropriate supersaturation degree. Ostwald-ripening assisted oriented attachment was believed to play a key role in the growth behavior. It provides an approach for the construction of hierarchical architectures with the advantage of precluding alien species. Raman scattering and room-temperature photoluminescence studies showed high consistency with respect to the crystallization improvement at elevated temperatures, which further showed that optical methods possess great potential in probing the microstructure of ZnO crystals.08/2008; -
Article: Supramolecular engineering of a 2D Kagomé lattice: synthesis, structures, and magnetic properties.
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ABSTRACT: Two 2D Mn (II) complexes, [Mn3(TzDC)2(phen)3] x 2 H2O (1; H3TzDC = 1,2,3-triazole-4,5-dicarboxylic acid, phen = 1,10-phenanthroline) and [Mn3(TzDC)2(bipy)3] x 4 H2O (2; bipy = 2,2'-bipyridine), were synthesized by hydrothermal reactions and characterized magnetically, and complex 1 was the first example of the chiral complex with a Kagomé lattice connectivity obtained through spontaneous resolution.Inorganic Chemistry 08/2008; 47(14):6115-7. · 4.60 Impact Factor -
Article: Single-crystalline and near-monodispersed NaMF3 (M = Mn, Co, Ni, Mg) and LiMAlF6 (M = Ca, Sr) nanocrystals from cothermolysis of multiple trifluoroacetates in solution.
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ABSTRACT: We report the synthesis of single-crystalline and near-monodispersed NaMF3 (M = Mn, Co, Ni, Mg), LiMAlF6 (M = Ca, Sr), and NaMgF3:Yb,Er nanocrystals (quasisquare nanoplates, nanorods, and nanopolygons) by the cothermolysis of multiple trifluoroacetates in hot combined organic solvents (oleic acid, oleylamine, and 1-octadecene). The nanocrystals were characterized by XRD, TEM, superconductive quantum interference device (SQUID), and upconversion luminescence spectroscopy. By regulating the polarity of the dispersant, the NaMF3 (M = Mn, Co, Ni) nanoplates were partially aligned to form nanoarrays on copper TEM grids. The sizes of the NaMF3 nanocrystals were easily tuned by the use of proper synthetic conditions such as reaction temperature and time and solvent composition. On the basis of a series of experiments in which the reaction conditions were varied, together with GC-MS and FTIR analysis, the reaction pathways for the formation of these nanocrystals from trifluoroacetate precursors were proposed. The magnetic measurements showed that the differently sized NaMnF3 square plates displayed interesting weak ferromagnetic behavior on the nanometer scale. The strong red upconversion luminescence emitted from the NaMgF3:Yb,Er nanorods under 980-nm near-IR laser excitation suggests that NaMgF3 may be a good candidate host material for red upconversion luminescence.Chemistry - An Asian Journal 09/2007; 2(8):965-74. · 4.50 Impact Factor -
Article: Iron Oxide Tube-in-Tube Nanostructures
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ABSTRACT: Single-crystalline hematite tube-in-tube nanostructures were prepared by a facile one-step hydrothermal method. The structure, shape, and formation mechanism of the tube-in-tube nanostructures were investigated. The results disclosed that the hematite tube-in-tube nanostructures were formed through a multisite dissolution process of the ellipsoid precursors. What is more, the tube-in-tube nanostructure is a single crystal in nature, and a simple combination of a small tube filling into a big one can be excluded. Single-crystalline magnetite and maghemite tube-in-tube nanostructures were also obtained via a simple reduction or reduction and reoxidation process with the hematite as the precursor. The facile and mild reaction route could be useful for the fabrication of complex tubular nanostructures.08/2007; -
Article: From trifluoroacetate complex precursors to monodisperse rare-earth fluoride and oxyfluoride nanocrystals with diverse shapes through controlled fluorination in solution phase.
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ABSTRACT: We report the first systematic synthesis of monodisperse rare-earth (RE=La to Lu, Y) fluoride and oxyfluoride nanocrystals with diverse shapes (trigonal REF3 triangular, truncated-triangular, hexagonal, and polygonal nanoplates; orthorhombic REF3 quadrilateral and zigzag-shaped nanoplates; cubic REOF nanopolyhedra and nanorods) from single-source precursors (SSP) of [RE(CF(3)COO)(3)] through controlled fluorination in oleic acid (OA)/oleylamine (OM)/1-octadecene (ODE). To selectively obtain REF3 or REOF nanocrystals, the fluorination of the RE-O bond to the RE-F bond at the nucleation stage was controlled by finely tuning the ratio of OA/ODE or OA/OM, and the reaction temperature. For phase-pure REF3 or REOF naocrystals, their shape-selective syntheses could be realized by further modifying the reaction conditions. The two-dimensional growth of the REF3 nanoplates and the one-dimensional growth of the REOF nanorods were likely due to the selective adsorption of the capping ligands on specific crystal planes of the nanocrystals. Those well-shaped nanocrystals with diverse geometric symmetries (such as D(3h), D(6h), C(2h), O(h), and D(nh)) displayed a remarkable capability to form self-assembled superlattices. By manipulating the solvent-substrate combination, the plate-shaped REF3 nanocrystals could form highly ordered nanoarrays by means of either the face-to-face formation or the edge-to-edge formation. By using this SSP strategy, we also obtained high-quality LaF3:Eu and LaF3:Eu/LaF3 triangular nanoplates that showed photoluminescent red emissions of Eu3+ ions sensitive to the surface effect.Chemistry 02/2007; 13(8):2320-32. · 5.93 Impact Factor -
Article: High-quality sodium rare-earth fluoride nanocrystals: controlled synthesis and optical properties.
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ABSTRACT: We report a general synthesis of high-quality cubic (alpha-phase) and hexagonal (beta-phase) NaREF4 (RE: Pr to Lu, Y) nanocrystals (nanopolyhedra, nanorods, nanoplates, and nanospheres) and NaYF(4):Yb,Er/Tm nanocrystals (nanopolyhedra and nanoplates) via the co-thermolysis of Na(CF3COO) and RE(CF3COO)3 in oleic acid/oleylamine/1-octadecene. By tuning the ratio of Na/RE, solvent composition, reaction temperature and time, we can manipulate phase, shape, and size of the nanocrystals. On the basis of its alpha --> beta phase transition behavior, along the rare-earth series, NaREF4 can be divided into three groups (I: Pr and Nd; II: Sm to Tb; III: Dy to Lu, Y). The whole controlled-synthesis mechanism can be explained from the point of view of free energy. Photoluminescent measurements indicate that the value of I610/I590 and the overall emission intensity of the NaEuF4 nanocrystals are highly correlative with the symmetries of the Eu3+ ions in both the lattice and the surface.Journal of the American Chemical Society 06/2006; 128(19):6426-36. · 9.91 Impact Factor -
Article: Phase evolution, texture behavior, and surface chemistry of hydrothermally derived scandium (hydrous) oxide nanostructures.
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ABSTRACT: Nanostructured scandium hydrous oxides were hydrothermally synthesized at 180 degrees C for 18 h, using NaOH, NH(4)OH, and KOH as the bases. They were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption, thermogravimetry and differential thermal analysis (TG-DTA), infrared and Raman spectroscopy, and pyridine adsorption. XRD and TEM measurements showed that the nature and concentration of the bases played key roles in determining the phasic composition, texture behavior (shape and size), and surface chemistry of the hydrothermal products. In addition, the shape evolution of the crystalline products seemed to be closely connected with their crystal structures. As the basicity value was raised from pH 10 to 5 mol L(-1) NaOH (or KOH), alpha-ScOOH nanorods, alpha-ScOOH nanosized hexagonal-like plates, and cubic Sc(OH)3 cubes/cuboids in micrometer size were produced in turn; while within pH 10-12 using NH4OH, gamma-ScOOH nanosized lozenge-like plates were mainly obtained. According to XRD, TEM, and TG-DTA results, all the as-prepared nanostructured ScOOH and micrometric Sc(OH)3 could be converted to cubic Sc2O3 with sustained crystalline shape via calcination at 500 degrees C. Pyridine adsorption revealed the existence of Lewis acid sites on the surfaces of the nanostructured alpha-ScOOH samples and some of their Sc2O3 counterparts calcined at 700 degrees C. The alpha-ScOOH nanorod sample displayed the strongest Lewis acidity among all the samples tested, due to its highest surface area as determined by N2 adsorption. Finally, an olation-oxolation process based on a dissolution/recrystallization mechanism accounts for the formation of various ScOOH polymorphs and Sc(OH)3 with different shapes.The Journal of Physical Chemistry B 11/2005; 109(39):18324-31. · 3.70 Impact Factor -
Article: Hierarchical assembly of SnO2 nanorod arrays on alpha-Fe2O3 nanotubes: a case of interfacial lattice compatibility.
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ABSTRACT: SnO2 nanorod arrays were hierarchically assembled onto the surface of alpha-Fe2O3 nanotubes via a facile solution method. Determined by the hexagonal geometrical nature of the alpha-Fe2O3 nanotubes, the heterostructures were of 6-fold symmetry. HRTEM characterizations demonstrated that the lattice mismatch at the interface was an important factor in determining the growth direction of the secondary nanorod arrays.Journal of the American Chemical Society 11/2005; 127(39):13492-3. · 9.91 Impact Factor -
Article: Single-crystalline iron oxide nanotubes.
Angewandte Chemie International Edition 08/2005; 44(28):4328-33. · 13.45 Impact Factor -
Article: Single‐Crystalline Iron Oxide Nanotubes
Angewandte Chemie 06/2005; 117(28):4402 - 4407. -
Article: General Synthesis and Characterization of Monocrystalline Lanthanide Orthophosphate Nanowires
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ABSTRACT: Monocrystalline LnPO4 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb) nanowires have been prepared in bulk quantities by a simple, facile, and clean solution-based hydrothermal method at 220−240 °C by finely tuning the acidity of the stock solutions. The length and width of the nanowires were in the range of 1−10 μm and 10−200 nm, respectively. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)Berichte der deutschen chemischen Gesellschaft 11/2003; 2003(22):4099 - 4104. · 2.94 Impact Factor -
Article: Controlled synthesis and characterization of monazite type monocrystalline nanowires of mixed lanthanide orthophosphates
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ABSTRACT: Monazite type monocrystalline nanowires of mixed lanthanide orthophosphates LnTb(PO4)2 (Ln=Ce, Nd, Sm) were synthesized via a simple hydrothermal process under optimal heat-treatment temperature (240 °C) and the starting acidity of the stock solution (pH 0.8). The as-synthesized nanowires were characterized by X-ray diffraction, transmission electron microscopy (TEM) and high-resolution TEM coupled with energy dispersive X-ray analysis, and infrared spectroscopy. The length and width of the nanowires were in the range of 2–10 μm and 20–350 nm, respectively.Solid State Communications.
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Institutions
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2003–2010
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Peking University
- National Laboratory of Rare Earth Material Chemistry and Application
Beijing, Beijing Shi, China
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