Browsing by Author "Chin, Tsung-Shune"

Now showing 1 - 4 of 4

Cone-stacked carbon nanofibers with cone angle increasing along the longitudinal axis
(2007-02-01)
Lin, Cheng-Te
;
Chen, Wen-Chao
;
Yen, Ming-Yu
;
Wang, Lung-Shen
;
Lee, Chi-Young
Using porous anodic aluminum oxide as template and petroleum pitch as precursor, a massive amount of uniform carbon nanofibers was obtained after thermal treatment. The diameter and length were 300 nm and 60 pm, respectively. The difference between these and the classic herringbone structure is that the angle between the graphenes and the fiber axis increases regularly along the axis instead of being fixed. TEM observations show that the nanofiber consists of stacked conical graphenes with cone angles that steadily increase from 60 degrees to 180 degrees along the fiber axis. This structure is the first to be produced without using catalytic CVD, and has not been reported using template procedures. The large deformation of the graphene planes at the tip of the nanofiber may produce interesting electronic applications. (c) 2006 Elsevier Ltd. All rights reserved.
Graphene structure in carbon nanocones and nanodiscs
(2007-12-18)
Lin, Cheng-Te
;
Lee, Chi-Young
;
Chiu, Hsin-Tien
;
Chin, Tsung-Shune
;
應用化學系
Carbon nanoparticles, like nanocones and nanodiscs, can be obtained by mechanical treatment of carbon nanofilaments. Microstructural studies suggest that in nanocones the conical graphene stacking with progressively increasing apex (cone) angles does not fully agree with current theoretical geometry models, such as a closed cones model and a cone-helix model. The unusual stacking form of nanocones was taken into account in a modified cone-helix model. The formation mechanism of the distinctive microstructure is attributed to the inclined anchoring effect, and the relaxation of internal stresses, which were induced by the confined pyrolysis process, resulting in easier disintegration by sonication the nanofilaments. This is disclosed for the first time in literature regarding the attainment of uniform carbon nanoparticles.
Quantitative appraisal of the interfacial anchoring state of polyaromatic hydrocarbons during the formation of C/C composites
(2010-04-01)
Lin, Cheng-Te
;
Tsai, Min-Chiao
;
Lee, Chi-Young
;
Chiu, Hsin-Tien
;
Chin, Tsung-Shune
The preferred anchoring state for polycyclic aromatic hydrocarbons (PAHs) pyrolyzed onto carbon substrates has been studied by semi-quantitative methods, examining their interfacial lattice arrangements. The samples were prepared by decomposing petroleum pitch inside carbon nanotubes resulting in a variety of crystallinities forming one-dimensional C/C composites. Studies indicate that the preferred anchoring state of PAH molecules depends on the nature of the substrate. Accordingly the PAHs in mesophase pitch should exhibit a face-on orientation on the carbonaceous substrates, including a graphite sheet, glassy carbon, and pyrolytic carbon. However, it showed that the anchoring state (face-on or edge-on) of PAH units can be altered even on carbonaceous substrates. The results demonstrated that in C/C composites the anchoring state is predominantly determined by the relative degree of crystallinity of the pitch/carbon substrate, and can be semi-quantitatively estimated using the I(D)/I(G) ratio from Raman spectra. Face-on anchoring is preferred when the I(D)/I(G); ratio of substrate is smaller (higher crystallinity) than that of the pyrolyzed precursor, whereas edge-on anchoring is favored when it is larger. Such an estimation method is useful in tailoring microstructures in the fabrication of C/C composites using PAH precursors. (C) 2009 Elsevier Ltd. All rights reserved.
Quasi two-dimensional carbon nanobelts synthesized using a template method
(2008-04-01)
Lin, Cheng-Te
;
Chen, Tsung-Han
;
Chin, Tsung-Shune
;
Lee, Chi-Young
;
Chiu, Hsin-Tien
Carbon nanobelts have been synthesized using nanoporous anodic alumina as template and ethanol as precursor. The length and width are tens of micrometers and 470 nm, respectively The thickness was measured to be 5 nm, exhibiting a high-aspect-ratio morphology. After annealing, the crystallinity of the nanobelts can be improved. The formation mechanism of such morphology is demonstrated as a radial deformation of large thin nanotubes. This is disclosed for the first time in the literature regarding the attainment of a quasi two-dimensional nanocarbon via a template route. Field emission measurements on the sample annealed at 800 degrees C show a turn-on voltage 3.25V/mu m and stable long-term emission efficiency The lower threshold voltage is attributed to the strong edge emitter effect. (C) 2008 Elsevier Ltd. All rights reserved.