| 1. |
- Hou, Yuanyuan, et al.
(författare)
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Comparative study of pressure-induced polymerization of C60 nanorods and single crystals
- 2007
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Ingår i: Journal of Physics Condensed Matter. - Bristol : Institute of Physics. - 0953-8984 .- 1361-648X. ; 19:42, s. 425207-
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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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| 2. |
- Hou, Yuanyuan, et al.
(författare)
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Photoluminescence properties of high-pressure-polymerized C60 nanorods in the orthorhombic and tetragonal phases.
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89:18, s. 181925-
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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.
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| 3. |
- Hou, Yuanyuan, et al.
(författare)
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Pressure-induced polymerization of nano- and submicrometer C60 rods into a rhombohedral phase
- 2006
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 423:1-3, s. 215-219
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Tidskriftsartikel (refereegranskat)abstract
- C-60 rods with nano- and submicrometer dimensions were polymerized at 4.5 GPa and 973 K. Raman spectroscopy showed that the material transformed into a rhombohedral polymeric structure under high pressure and high temperature (HPHT) conditions. The HPHT polymerized samples keep the original rod shape. The position dependence of photoluminescence (PL) spectra have been studied on the rhombohedral polymer C60 rods at room temperature. The intensity of the 1.74 eV peak from the rhombohedral phase varies systematically between the edge of and the middle of the rod. Our results indicate that the 1.74 eV peak originates from surface defects.
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| 4. |
- Liu, Bingbing, et al.
(författare)
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High pressure and high temperature induced polymeric C60 nanocrystal
- 2008
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Ingår i: Diamond and related materials, vol. 17, issue 4-5. - Amsterdam : Elsevier B.V.. ; , s. 620-623
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Konferensbidrag (refereegranskat)abstract
- In this paper, C60 nanosheets with polymeric phases have been obtained under various high pressures and high temperatures, including orthorhombic and tetragonal polymeric phases. The structures have been identified and compared with those of nanorods by photoluminescence and Raman spectroscopies. The main fluorescence band shifted from 1.70 eV in the monomeric phase to near infrared in the polymeric phase when pressure and temperature were increased. The difference of photoluminescence and Raman spectra between nanosheets and nanorods samples treated under the same conditions is probably caused by different polymerization degree in these samples because of different shapes.
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| 5. |
- Liu, Bingbing, et al.
(författare)
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High pressure and high temperature induced polymeric C60 nanorods and their photoluminiscence properties.
- 2007
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Ingår i: Materials Research at High Pressure. - Warrendale : Maerials Research Society. - 9781558999442 ; , s. 99-103
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Konferensbidrag (refereegranskat)abstract
- We report that C60 nanorods of three polymeric phases have been synthesized under high pressure and high temperature and that the photoluminescence properties of these polymeric nanorods also have been studied. C60 nanorods were fabricated by a facile solution evaporation method. Raman spectra indicate that this material transformed into orthorhombic, tetragonal and rhombohedral polymeric phases under various high pressure and high temperature conditions. SEM measurements show that the shape of the nanorods can be kept under quasi-hydrostatic pressure condition. The photoluminescence intensity of the polymeric C60 nanorods has been enhanced compared with that of the pristine C60 nanorods. The main fluorescence band shifted from 1.70 eV in the monomeric phase to near infrared in the polymeric phase when pressure and temperature were increased. The enhanced fluorescence with adjustable frequency for different polymeric C60 nanorods makes possible potential application in luminescent nanomaterials.
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| 6. |
- Liu, Bingbing, et al.
(författare)
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High-pressure induced polymerization of C60 nanorods
- 2005
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Ingår i: Proceedings of the Joint 20th AIRAPT and 43rd EHPRG Conf. on High Pressure Science and Technology, Karlsruhe 2005. - 3923704496 ; , s. Nanomat-O133
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)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. |
- Wang, Lin, et al.
(författare)
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High-pressure studies of Nano/sub-micrometer C70 rods
- 2005
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Ingår i: High Energy Physics and Nuclear Physics B. - 0254-3052. ; 29:Supplement, s. 112-115
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Tidskriftsartikel (refereegranskat)abstract
- We have successfully synthesized C-70 rods in nano/sub-micrometers scale by evaporating solvent method. The diameter of the as grown C-70 rods is similar to 500 nm, and the length is similar to 10 mu m. The EDXD pattern and Raman spectroscopy for as -grown sample indicate that the as grown C-70 rod is in hcp structure. The pressure-induced structural phase transition has been studied by using DAC combined with EDXD and Raman spectroscopy methods under quasi-hydrostatic pressure up to 26.1GPa. It is found that hcp structure transforms into amorphous phase for C-70 rods in the pressure range from 23.3 to 26.1GPa, which is higher than the transformation pressure for bulk C-70 crystals. The phase transition is irreversible and it is induced by the collapse of C-70 cage.
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| 8. |
- Wang, Lin, et al.
(författare)
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Highly Enhanced Luminescence from Single-Crystalline C60·1m-xylene Nanorods
- 2006
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 18:17, s. 4190-4194
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Tidskriftsartikel (refereegranskat)abstract
- Single-crystalline C60â1m-xylene nanorods with a hexagonal structure were successfully synthesizedby evaporating a C60 solution in m-xylene at room temperature. The ratio of the length to the diameterof the nanorods can be controlled in the range of 10 to over 1000 for different applications. Thephotoluminescence (PL) intensity of the nanorods is about 2 orders of magnitude higher than that forpristine C60 crystals in air. Both UV and Raman results indicate that there is no charge transfer betweenC60 and m-xylene. It was found that the interaction between C60 and m-xylene molecules is of the vander Waals type. This interaction reduces the icosahedral symmetry of C60 molecule and induces strongPL from the solvate nanorods.
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| 9. |
- Wang, Lin, et al.
(författare)
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Synthesis and high pressure induced amorphization of C60 nanosheets
- 2007
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 91:10, s. 103112-
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Tidskriftsartikel (refereegranskat)abstract
- C-60 nanosheets with thicknesses in the nanometer range were synthesized by a simple method. Compared to bulk C-60, the lattice of the nanosheets is expanded by about 0.4%. In situ Raman spectroscopy and energy-dispersive x-ray diffraction under high pressures have been employed to study the structure of the nanosheets. The studies indicate that the bulk modulus of the C-60 nanosheets is significantly larger than that of bulk C-60. The C-60 cages in nanosheets can persist at pressures over 30 GPa, 3 GPa higher than for bulk C-60. These results suggest that C-60 crystals in even small size will be a potential candidate of superhard materials.
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| 10. |
- Wang, Lin, et al.
(författare)
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Synthesis of thin, rectangular C60 nanorods using m-xylene as shape controller
- 2006
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Ingår i: Advanced Materials. - : Wiley Interscience. - 0935-9648 .- 1521-4095. ; 18:14, s. 1883-1888
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Tidskriftsartikel (refereegranskat)abstract
- Thin, rectangular C60 nanorods in face-centered cubic structure are synthesized by using m-xylene as a shape controller. These unusual nanorods can easily grow on various substrates. The smallest nanorods have widths smaller than 30 nm. The nanorods are highly crystalline in single phase. A significant expansion of the lattice constant is also found in the C60 nanorods when their widths decrease below about 80 nm.
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