scholarly journals Effects of catalyst support and chemical vapor deposition condition on synthesis of multi-walled carbon nanocoils

2016 ◽  
Author(s):  
Yoshiyuki Suda ◽  
Tetsuo Iida ◽  
Hirofumi Takikawa ◽  
Toru Harigai ◽  
Hitoshi Ue ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Catalyst Support ◽  
Chemical Vapor ◽  
Deposition Condition

Growth of Highly Luminescent Silicon Nanocrystals by Rapid Thermal Chemical Vapor Deposition

2005 ◽  
Vol 277-279 ◽  
pp. 977-982 ◽  
Author(s):  
Hea Jeong Cheong ◽  
Jung Hyun Kang ◽  
Jae Kwon Kim ◽  
Kim Yong
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Silicon Nanocrystals ◽  
Quantum Confinement Effect ◽  
Chemical Vapor ◽  
Thickness Variation ◽  
Deposition Condition ◽  
Thermal Chemical Vapor Deposition ◽  
Si Nanocrystals ◽  
Si Wafer

We investigate the growth of highly luminescent silicon nanocrystals by rapid thermal chemical vapor deposition (RTCVD), employing SiH4 and N2O as source gases. For [N2O]/[SiH4] = 7 ∼ 8 and a growth temperature of 650°C, we obtain the optimized deposition condition for silicon rich oxide (SRO) layer having highly luminescent Si nanocrystals after post-deposition annealing. The cross sectional transmission electron microscope investigation reveals the existence of Si nanocrystals in the SRO matrix. Thus, the photoluminescence (PL) from the SRO layer is attributed to the quantum confinement effect of carriers in Si nanocrystals. Based on a single layer growth study, we fabricate ultra-thin SRO/SiO2 superlattice having 25 periods on a 3-inch Si wafer. The superlattice has continuous thickness variation from the center to the edge positions of the Si wafer due to inherent wafer temperature variation during growth. Photoluminescence spectra show a systematic blue-shift from a thicker position (center position) to a thinner position (edge position) which is indicative of nanocrystal size control by SRO layer thickness in the superlattice.

Catalyst Support and Pretreatment Effects on Carbon Nanotubes Synthesis by Chemical Vapor Deposition of Methane on Iron over SiO2, Al2O3 or MgO

2009 ◽  
Vol 7 (1) ◽  
Author(s):  
M. Esmaieli ◽  
A. Khodadadi ◽  
Y. Mortazavi
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Iron Catalyst ◽  
Supported Catalysts ◽  
Catalyst Support ◽  
Multiwall Carbon Nanotubes ◽  
Chemical Vapor ◽  
Pretreatment Conditions ◽  
Temperature Programmed

In this study we report the effects of support and pretreatment conditions on growth of carbon nanotubes (CNTs) by chemical vapor deposition of methane on iron catalyst supported on MgO, silica or alumina. The iron was impregnated onto the supports, and then the samples were dried, calcined at 550°C and pretreated in either helium or hydrogen up to 1000°C before exposure to methane as a carbon source for CNTs growth. Temperature programmed reduction (TPR) of the fresh catalysts and the ones pre-treated in He and in H2 shows various interactions of the iron with supports at pretreatment conditions. The CNTs are characterized by SEM, Raman, FTIR, and TEM. The IG/ID of Raman spectroscopy are 6.2, 3.8 and 0.7 for the CNTs grown on the MgO, alumina, and silica-supported iron catalysts pretreated in helium, respectively. When the Fe/MgO catalyst is pretreated in hydrogen the IG/ID ratio dramatically reduces to 0.8. A less significant effect of pretreating of the catalysts in hydrogen is observed for silica- and alumina-supported catalysts. RBM peaks of Raman spectra along with TEM results indicate the formation of bundles of 0.8-1.2 nm single-wall as well as multiwall carbon nanotubes on the Fe/MgO catalyst pre-treated in He.

Analysis of plasma for carbon nanotube growth by plasma-enhanced chemical vapor deposition

2005 ◽  
Vol 901 ◽  
Author(s):  
Atsushi Ozeki ◽  
Yoshiyuki Suda ◽  
Atsushi Okita ◽  
Junji Nakamura ◽  
Akinori Oda ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Carbon Nanotube ◽  
Relative Density ◽  
Vapor Deposition ◽  
Gas Flow ◽  
Catalyst Support ◽  
Chemical Vapor ◽  
Rf Plasma ◽  
Number Density ◽  
Support Materials

AbstractOptical emission spectra of a CH4/H2/Ar gas mixture plasma were observed during carbon nanotube (CNT) growth in RF plasma-enhanced chemical vapor deposition. CNTs with diameters of ∼10-30 nm and length of ∼6 μm were grown on double- and triple-layered films of catalyst/support materials (FexOy/TiO2 and Al2O3/FexOy/Al2O3) at the total gas pressures of 1-10 Torr with gas flow rates of CH4 = 27 sccm, H2 = 3 sccm, and Ar = 1 sccm. The number density of CNTs increased with the gas pressure, and Al2O3/FexOy/Al2O3 (each thickness of 1 nm) film yielded the thinnest CNTs with a high number density among the present catalysts. The spatial distributions of H atom relative density in the plasma were obtained by actinometry. The H relative density decreased with the pressure, and this suggests the suppression of CH3 radical generation in the plasma.

Controlling the Structure of Carbon Deposit by Nitrogen Doping Catalytic Chemical Vapor Deposition Synthesis

2021 ◽  
Vol 21 (4) ◽  
pp. 2413-2418
Author(s):  
K. Németh ◽  
G. P. Szekeres ◽  
D. Fejes ◽  
B. Reti ◽  
J. W. Seo ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Catalyst Support ◽  
Chemical Vapor ◽  
Catalytic Chemical Vapor Deposition ◽  
Transmission Electron ◽  
Significant Difference ◽  
Multi Walled Carbon Nanotubes

Nitrogen doped multi-walled carbon nanotubes and other carbon nanoparticles were synthesized by catalytic chemical vapor deposition of tripropylamine and acetylene on CaCO3-supported cobalt catalyst (5 wt%), prepared by impregnation, and various precursors. Each synthesis was performed by using either the pure nitrogenous organic compound or its mixture with acetone. Transmission electron microscopy studies revealed a significant difference both in the yield and the diversity of the carbon deposits. Every synthesis resulted in bamboo-like nanotubes, and nearly all of them also in onion-like structures. Electron energy loss spectroscopy studies of the samples indicated the presence of nitrogen and calcium (caused by the catalyst support). High-resolution transmission electron microscopy and X-ray diffraction measurements were also performed to characterize the samples.

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