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Träfflista för sökning "WFRF:(Yao Mingguang) "

Sökning: WFRF:(Yao Mingguang)

  • Resultat 1-10 av 38
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1.
  • Cui, Wen, et al. (författare)
  • Reversible pressure-induced polymerization of Fe(C5H5)(2) doped C-70
  • 2013
  • Ingår i: Carbon. - Pergamon-Elsevier Science. - 0008-6223. ; 62, s. 447-454
  • Tidskriftsartikel (refereegranskat)abstract
    • High pressure Raman, IR and X-ray diffraction (XRD) studies have been carried out on C-70(Fe(C5H5)(2))(2) (hereafter, "C-70(Fc)(2)") sheets. Theoretical calculation is further used to analyze the Electron Localization Function (ELF) and charge transfer in the crystal and thus to understand the transformation of C-70(Fc)(2) under pressure. Our results show that even at room temperature dimeric phase and one dimensional (1D) polymer phase of C-70 molecules can be formed at about 3 and 8 GPa, respectively. The polymerization is found to be reversible Upon decompression and the reversibility is related to the pressure-tuned charge transfer, as well as the overridden steric repulsion of counter ions. According to the layered structure of the intercalated ferrocene molecules formed in the crystal, we suggest that ferrocene acts as not only a spacer to restrict the polymerization of C-70 molecules within a layer, but also as charge reservoir to tune the polymerization process. This supplies a possible way for us to design the polymerization of fullerenes at suitable conditions.
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2.
  • Cui, Wen, et al. (författare)
  • Synthesis of alkali-metal-doped C60 nanotubes
  • 2011
  • Ingår i: Diamond and Related Materials vol. 20, issue 2 : Proceedings of New Diamond and Nano Carbon Conference (NDNC 2010). - Elsevier. ; s. 93-96
  • Konferensbidrag (refereegranskat)abstract
    • C60 nanotubes have been synthesized by a solution–solution method. After degassing in a dynamic vacuum, the C60 nanotubes were doped with alkali metals by means of vapor evaporation method. Different temperatures have been studied to evaporate the alkali metals for the doping experiments. Raman spectrum was further employed to analyze the doping concentration of the obtained samples. It was found that all three alkali metals (Li, Na and K) used can be efficiently doped into the C60 nanotubes, forming AxC60 nanotubes. The doping concentration of Li, Na changed from low to high level, depending on the experiment temperatures, while K doping always gave saturated doping. The melt points, the ionic sizes and vapor pressures of alkali metals were thought to affect the final doping results.
3.
  • Hou, Yuanyuan, et al. (författare)
  • Comparative study of pressure-induced polymerization of C60 nanorods and single crystals
  • 2007
  • Ingår i: Journal of Physics Condensed Matter. - Bristol : Institute of Physics. - 0953-8984. ; 19:42, s. 425207
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, we report a comparative study of pressure-induced polymerization in C60 nanorods and bulk single crystals, treated simultaneously under various pressures and temperatures in the same experiment. For both materials, orthorhombic, tetragonal and rhombohedral phases have been produced under high pressure and high temperature. The structures have been identified and compared between the two sample types by Raman and photoluminescence spectroscopy. There are differences between the Raman and photoluminescence spectra from the two types of materials for all polymeric phases, but especially for the tetragonal phase. From the comparison between nanorods and bulk samples, we tentatively assign photoluminescence peaks for various polymeric phases.
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4.
  • Hou, Yuanyuan, et al. (författare)
  • Photoluminescence properties of high-pressure-polymerized C60 nanorods in the orthorhombic and tetragonal phases.
  • 2006
  • Ingår i: Applied Physics Letters. - 0003-6951. ; 89:18, s. 181925
  • Tidskriftsartikel (refereegranskat)abstract
    • C60 nanorods in two polymeric phases have been synthesized under different high pressure and high temperature conditions. Orthorhombic and tetragonal phases have been identified from Raman spectra. The rod shape can be kept under quasihydrostatic pressure. The photoluminescence intensity of the polymeric C60 nanorods has been greatly enhanced compared with that of pristine C60 nanorods. The main fluorescence band shifted from 730  nm in the unpolymeric phase to 748  nm and near infrared 780  nm in the orthorhombic and tetragonal phases, respectively. The enhanced photoluminescence with tunable frequency for different polymeric C60 nanorods suggests potential applications in luminescent nanomaterials.
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5.
  • Jiang, Linhai, et al. (författare)
  • Controlled Synthesis of CeO2/Graphene Nanocomposites with Highly Enhanced Optical and Catalytic Properties
  • 2012
  • Ingår i: The Journal of Physical Chemistry C. - 1932-7447. ; 116:21, s. 11741-11745
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, CeO2 nanocubes with the (200)-terminated surface/graphene sheet composites have been prepared successfully by a simple hydrothermal method. It is found that the CeO2 nanocubes with high crystallinity and specific exposed surface are well dispersed on well-exfoliated graphene surface. The (200)-terminated surface/graphene sheet composites modified electrode showed much higher sensitivity and excellent selectivity in its catalytic performance compared to a CeO2 nanoparticle-modified electrode. The photoluminescence intensity of the CeO2 anchored on graphene is about 30 times higher than that of pristine CeO2 crystals in air. The higher oxygen vacancy concentration in CeO2 is supposed to be an important cause for the higher photoluminescence and better electrochemical catalytic performance observed in the (200)-terminated surface/graphene sheet composites. Such ingenious design of supported well-dispersed catalysts in nanostructured ceria catalysts, synthesized in one step with an exposed high-activity surface, is important for technical applications and theoretical investigations.
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6.
  • Liu, Bingbing, et al. (författare)
  • High-pressure induced polymerization of C60 nanorods
  • 2005
  • Ingår i: Proceedings of the Joint 20th AIRAPT and 43rd EHPRG Conf. on High Pressure Science and Technology, Karlsruhe 2005. - 3-923704-49-6. ; s. Nanomat-O133
  • Konferensbidrag (övrigt vetenskapligt)abstract
    • C60 nanorods, about 200 nm in diameter and several micrometers in length and with a rectangular cross section, have been synthesized by a simple solution-growth method. Raman spectroscopy and TEM indicate that the C60 nanorods have a fcc crystalline structure similar to that of pristine C60. Nanorods were polymerized at high temperature and high pressure below 2 GPa. Two different polymeric structures, orthorhombic and tetragonal as determined by Raman spectroscopy, have been obtained under different high temperature and high pressure conditions. The high-pressure induced polymeric samples keep the original nanometer scale rod shape.
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7.
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8.
  • Liu, Dedi, et al. (författare)
  • Effects of alcohols on shape-tuning and luminescence-enhancing of C70 nanocrystals
  • 2013
  • Ingår i: Optical materials (Amsterdam). - Elsevier. - 0925-3467. ; 36:2, s. 449-454
  • Tidskriftsartikel (refereegranskat)abstract
    • C70 nanotubes, nanorods and nanoparticles were produced by introducing a series of alcohols as precipitant into a C70/m-xylene solution. The effects of alcohols with different carbon chain lengths on the shape control of C70 nanocrystals were investigated. Alcohols with more than two carbon atoms in the longest chain linked to the hydroxyl groups induced the formation of C70 nanotube/rods. In contrast, alcohols containing two or fewer carbon atoms resulted in C70 nanoparticles. Structural analysis indicated that alcohol molecules exist in the C70 nanocrystals, forming solvated structures. The freshly formed C70 nanotubes and nanoparticles have orthorhombic and hexagonal solvated structures, respectively. Room temperature photoluminescence was further carried out on the solvated C70 nanocrystals to investigate their optical properties. We found that the luminescence intensities of C70 nanocrystals were significantly enhanced by the introduction of alcohols.
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9.
  • Liu, Dedi, et al. (författare)
  • High pressure and high temperature induced polymerization of C60 nanotubes
  • 2011
  • Ingår i: CrysteEngComm. - Royal Society of Chemistry. - 1466-8033. ; 13:10, s. 3600-3605
  • Tidskriftsartikel (refereegranskat)abstract
    • C60 nanotubes with outer diameters ranging from 400–800 nm were polymerized at 1.5 GPa, 573 K and 2.0 GPa, 700 K, respectively. Raman and photoluminescence spectroscopy were employed to characterize the polymeric phases of the treated samples. Both Raman and photoluminescence spectra showed that the C60 nanotubes transformed into the dimer and orthorhombic phases under the two different conditions, respectively. The photoluminescence peaks were tuned from visible to near infrared range. Comparative studies indicated that C60 nanotubes were more difficult to polymerize than bulk C60 material under the same conditions due to the nanoscale size effect in the C60 nanotubes.
10.
  • Liu, Dedi, et al. (författare)
  • In situ Raman and photoluminescence study on pressure-induced phase transition in C60 nanotubes
  • 2012
  • Ingår i: Journal of Raman Spectroscopy. - 0377-0486. ; 43:6, s. 737-740
  • Tidskriftsartikel (refereegranskat)abstract
    • Single crystalline C60 nanotubes having face-centered-cubic structure with diameters in the nanometer range were synthesized by a solution method. In situ Raman and photoluminescence spectroscopy under high pressure were employed to study the structural stabilities and transitions of the pristine C60 nanotubes. A phase transition, probably because of the orientational ordering of C60 molecules, from face-centered-cubic structure to simple cubic structure occurred at the pressure between 1.46 and 2.26 GPa. At above 20.41 GPa, the Raman spectrum became very diffuse and lost its fine structure in all wavenumber regions, and only two broad and asymmetry peaks initially centered at 1469 and 1570cm-1 were observed, indicating an occurrence of amorphization. This amorphous phase remained to be reversible until 31.1 GPa, and it became irreversible to the ambient pressure after the pressure cycle of 34.3 GPa was applied.
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  • Resultat 1-10 av 38
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