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Sökning: WFRF:(Yao Mingguang)

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  • 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.
  • Cui, Jinxing, et al. (författare)
  • Structural Deformation of Sm@C88under High Pressure
  • 2015
  • Ingår i: Scientific Reports. - Nature Publishing Group. - 2045-2322. ; 5
  • Tidskriftsartikel (refereegranskat)abstract
    • We have studied the structural transformation of Sm@C88 under pressure up to 18 GPa by infraredspectroscopy combined with theoretical simulations. The infrared-active vibrational modes of Sm@C88 at ambient conditions have been assigned for the first time. Pressure-induced blue and red shiftsof the corresponding vibrational modes indicate an anisotropic deformation of the carbon cage uponcompression. We propose that the carbon cage changes from ellipsoidal to approximately sphericalaround 7 GPa. A smaller deformation of the carbon bonds in the area close to the Sm atom in thecage suggests that the trapped Sm atom plays a role in minimizing the compression of the adjacentbonds. Pressure induced a significant reduction of the band gap of the crystal. The HOMO-LUMOgap of the Sm@C88 molecule decreases remarkably at 7 GPa as the carbon cage is deformed. Also,compression enhances intermolecular interactions and causes a widening of the energy bands. Botheffects decrease the band gap of the sample. The carbon cage deforms significantly above 7 GPa,from spherical to a peanut-like shape and collapses at 18 GPa.
  • Cui, Wen, et al. (författare)
  • High pressure and high temperature induced polymerization of doped C60 materials
  • 2016
  • Ingår i: Carbon. - Elsevier. - 0008-6223. ; 109, s. 269-275
  • Tidskriftsartikel (refereegranskat)abstract
    • Several metastable doped C60 polymers are synthesized under high pressure and high temperature (1.5GPa, 573K and 2GPa, 700K, respectively), using C60/ferrocene (Fc, Fe(C5H5)2), C60/Ni(OEP) and C60/AgNO3 as starting materials. Raman and IR spectroscopy are used to study the polymerization of these samples after HPHT treatment. It is found that the polymerization degree is always lower than that of pure C60 treated at same conditions, which is attributed to the space limitation by the dopants. We also find that even at same conditions, the three doped materials form different polymeric phases of the doped materials. This is attributed to the unique initial lattice structures and the different degrees of spatial confinement provided by the dopants.
  • Cui, Wen, et al. (författare)
  • Synthesis of alkali-metal-doped C60 nanotubes
  • 2011
  • Ingår i: Diamond and Related Materials : Proceedings of New Diamond and Nano Carbon Conference (NDNC 2010). ; 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.
  • Du, Mingrun, et al. (författare)
  • High pressure infrared spectroscopy study on C60*CS2 solvates
  • 2017
  • Ingår i: Chemical Physics Letters. - Elsevier. - 0009-2614. ; 669, s. 49-53
  • Tidskriftsartikel (refereegranskat)abstract
    • High pressure IR study has been carried out on C-60*CS2 solvates up to 34.8 GPa. It is found that the intercalated CS2 molecules significantly affect the transformations of C-60 molecules under pressure. As a probe, the intercalated CS2 molecules can well detect the orientational ordering transition and deformation of C-60 molecules under pressure. The chemical stability of CS2 molecules under pressure is also dramatically enhanced due to the spacial shielding effet from C-60 molecules around in the solvated crystal. These results provide new insight into the effect of interactions between intercalants and fullerenes on the transformations in fullerene solvates under pressure.
  • Du, Mingrun, et al. (författare)
  • New ordered structure of amorphous carbon clusters induced by fullerene-cubane reactions
  • 2018
  • Ingår i: Advanced Materials. - Wiley-VCH Verlagsgesellschaft. - 0935-9648. ; 30
  • Tidskriftsartikel (refereegranskat)abstract
    • As a new category of solids, crystalline materials constructed with amorphous building blocks expand the structure categorization of solids, for which designing such new structures and understanding the corresponding formation mechanisms are fundamentally important. Unlike previous reports, new amorphous carbon clusters constructed ordered carbon phases are found here by compressing C8H8/C60 cocrystals, in which the highly energetic cubane (C8H8) exhibits unusual roles as to the structure formation and transformations under pressure. The significant role of C8H8 is to stabilize the boundary interactions of the highly compressed or collapsed C60 clusters which preserves their long-range ordered arrangement up to 45 GPa. With increasing time at high pressure, the gradual random bonding between C8H8 and carbon clusters, due to “energy release” of highly compressed cubane, leads to the loss of the ability of C8H8 to stabilize the carbon cluster arrangement. Thus a transition from short-range disorder to long-range disorder (amorphization) occurs in the formed material. The spontaneous bonding reconstruction most likely results in a 3D network in the material,which can create ring cracks on diamond anvils.
  • 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.
  • 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
    • C60nanorods in two polymeric phases have been synthesized under differenthigh pressure and high temperature conditions. Orthorhombic and tetragonal phaseshave been identified from Raman spectra. The rod shape canbe kept under quasihydrostatic pressure. The photoluminescence intensity of thepolymeric C60 nanorods has been greatly enhanced compared with thatof pristine C60 nanorods. The main fluorescence band shifted from730  nm in the unpolymeric phase to 748  nm and near infrared780  nm in the orthorhombic and tetragonal phases, respectively. The enhancedphotoluminescence with tunable frequency for different polymeric C60 nanorods suggestspotential applications in luminescent nanomaterials.
  • 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.
  • Liu, Bingbing, et al. (författare)
  • Effects of silver films with different nano-particle sizes on SERS of single-walled carbon nanotubes
  • 2005
  • Ingår i: Chemical Journal of the Chinese Universities. - 0251-0790. ; 26:10, s. 1930-1933
  • Tidskriftsartikel (refereegranskat)abstract
    • Surface-enhanced Raman scattering (SERS) spectra of single-walled carbon nanotubes (SWCNTs) on silver films with different nano-particle sizes from 20 to 100 nm deposited on quartz and glass substrates were studied systematically. The characteristic Raman spectral features of SWCNT G-band and D-band were analyzed. The two bands show a similar tendency with the change of nano-particle size of silver on quartz and glass substrates. The position and the intensity of the G-band are less sensitive to the films' silver particle sizes in the studied range, indicating that hexagonal carbon rings are stable and have a weak interaction with silver films. The shape of the D-band depends on the silver size. The smaller the silver particle size, the more the contribution of high frequency vibrations to the D-band, indicating that disorder carbon has a strong interaction with the active silver films.
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