scholarly journals Three-Day Continuous Exposure Monitoring of CNT Manufacturing Workplaces

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Ji Hyun Lee ◽  
Kang Ho Ahn ◽  
Sun Man Kim ◽  
Ellen Kim ◽  
Gun Ho Lee ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Multiwall Carbon Nanotubes ◽  
Chemical Vapor ◽  
Single Wall Carbon Nanotubes ◽  
Background Concentration ◽  
Continuous Exposure ◽  
Work Processes ◽  
Scanning Mobility Particle Sizer ◽  
Personal Sampling ◽  
Particle Sizer

Continuous monitoring for possible exposure to carbon nanotubes was conducted over a period of 2 to 3 days at workplaces that manufacture multiwall carbon nanotubes (MWCNTs) and single wall carbon nanotubes (SWCNTs). To estimate the potential emission of carbon nanotubes (CNTs) and potential exposure of workers, personal sampling, area monitoring, and real-time monitoring using an scanning mobility particle sizer (SMPS) and dust monitor were conducted at workplaces where the workers manufactured CNTs. The personal and area sampling of the total suspended particulate (TSP) at the MWCNT manufacturing facilities ranged from 0.031 to 0.254 and from N.D (not detected) to 0.253 mg/m3, respectively. This 2- to 3-day monitoring study found that nanoparticles were released when opening the chemical vapor deposit (CVD) reactor door after the synthesis of MWCNTs, when transferring the MWCNTs to containers and during blending and grinding. However, distinguishing the background concentration from the work process particle emission was complicated due to sustained and even increased particle concentrations after the work processes were terminated. The MWCNTs sampled for transmission electron microscopy (TEM) observation exhibited a tangled shape with no individual dispersed CNT structures.

MICROSCOPIC CHARACTERIZATION OF THIN-MULTIWALL CARBON NANOTUBES SYNTHESIZED BY CATALYTIC CVD METHOD WITH MESOPOROUS SILICA

NANO ◽  
2006 ◽  
Vol 01 (03) ◽  
pp. 207-212 ◽  
Author(s):  
PALANISAMY RAMESH ◽  
KENICHI SATO ◽  
YUJI OZEKI ◽  
MASAHITO YOSHIKAWA ◽  
NAOKI KISHI ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Mesoporous Silica ◽  
Multiwall Carbon Nanotubes ◽  
Chemical Vapor ◽  
Single Wall Carbon Nanotubes ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Structural Deformations ◽  
Multiwall Carbon

Carbon nanotubes with 1–6 walls have been grown on cobalt-loaded mesoporous silica (i.e., MCM41) by using acetylene catalytic chemical vapor deposition. It is found that titanium grafting on the MCM41 pore walls prior to cobalt loading promotes the growth of nanotubes with 1–6 walls. As-grown nanotube material is found to be a mixture of single-wall carbon nanotubes (SWNTs), double-wall carbon nanotubes (DWNTs) and thin-multiwall carbon nanotubes (t-MWNTs) with 3–6 walls. Annealing of the as-grown nanotubes has reduced the amount of SWNTs in the nanotube mixture. Several structural deformations of the t-MWNTs are observed during transmission electron microscopy (TEM) analysis. Complete or partial collapse of the t-MWNTs is also found due to these structural deformations. Graphite-like domains developed at the collapsed regions stabilize these structural deformations.

Thermal and Thermoelectric Measurements of Low Dimensional Nanostructures

2003 ◽  
Author(s):  
Choongho Yu ◽  
Wanyoung Jang ◽  
Tobias Hanrath ◽  
Dohyung Kim ◽  
Zhen Yao ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Thermoelectric Properties ◽  
Multiwall Carbon Nanotubes ◽  
Chemical Vapor ◽  
Single Wall Carbon Nanotubes ◽  
Thermoelectric Measurements ◽  
Improved Design ◽  
Sno2 Nanobelts ◽  
Low Dimensional

Low dimensional materials have unique thermal and thermoelectric properties that can be very different from their bulk counterparts. In a previous work, we and our collaborators have developed a microdevice for measuring thermal and thermoelectric properties of multiwall carbon nanotubes. Here, we used an improved design of the device for measuring single wall carbon nanotubes, Ge nanowires, and SnO2 nanobelts. These nanostructures are trapped between two adjacent symmetric silicon nitride membranes of the micro device using either a wet deposition method or in-situ chemical vapor deposition. The measurements provide the critically needed data of the unique thermophysical properties of these nanomaterials.

CONTROLLABLE CHEMICAL VAPOR DEPOSITION SYNTHESIS OF SINGLE-WALL CARBON NANOTUBES USING MIST FLOW METHOD

NANO ◽  
2012 ◽  
Vol 07 (06) ◽  
pp. 1250045 ◽  
Author(s):  
YUN SUN ◽  
RYO KITAURA ◽  
TAKUYA NAKAYAMA ◽  
YASUMITSU MIYATA ◽  
HISANORI SHINOHARA
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Single Wall Carbon Nanotubes ◽  
Flow Method ◽  
Mist Flow ◽  
Mean Diameter ◽  
The Mean

The influences of synthesis parameters on the mean diameter and diameter distribution of as-grown single-wall carbon nanotubes (SWCNTs) with chemical vapor deposition (CVD) using the mist flow method have been investigated in detail with Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). We found that CVD reaction temperature and flow rate play an essential role in controlling the mean diameter and the quality of as-grown SWCNTs. Furthermore, we found that the carbon supply kinetics can be a dominant factor to determine the diameter of as-grown SWCNTs in the present mist flow method. Under a different combination of various parameters, the mean diameter of SWCNTs can be varied from 0.9 nm to 1.5 nm controllably.

Chemical vapor deposition of nickel-group metals on multiwall carbon nanotubes

2007 ◽  
Vol 85 (10) ◽  
pp. 645-650 ◽  
Author(s):  
Maoqi Feng ◽  
Richard J Puddephatt
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Carbon Nanotube ◽  
Low Temperature ◽  
Vapor Deposition ◽  
Multiwall Carbon Nanotubes ◽  
Chemical Vapor ◽  
Pt Films ◽  
Bimetallic Films ◽  
Multiwall Carbon

Chemical vapor deposition (CVD) of Ni, Pd, and Pt films and of Ni/Pd and Pd/Pt bimetallic films on multiwall carbon nanotubes (MWCNTs) can be effected at low temperature if the nanotubes are pretreated by CVD of titanium carbide. In the absence of the pretreatment, the CVD leads to formation of isolated nanoparticles of the nickel-group metals. The metallized MWCNTs are curved or kinked, as a result of the interaction with the metal. Preliminary oxidation of the carbon nanotubes allows easier metallization, and the bending of the metallated nanotubes is not observed in this case.Key words: Chemical vapor deposition, platinum, palladium, nickel, carbon, nanotube.

Synthesis and Characterization of Carbon Nanotubes from Palm Oil by Aerosol-Assisted CVD

2013 ◽  
Vol 667 ◽  
pp. 218-223
Author(s):  
M. Maryam ◽  
A.B. Suriani ◽  
M.S. Shamsudin ◽  
Mohamad Rusop Mahmood
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Palm Oil ◽  
Deposition Temperature ◽  
Multiwall Carbon Nanotubes ◽  
Single Wall Carbon Nanotubes ◽  
X Ray ◽  
Weight Percentage ◽  
Transmission Electron ◽  
Reaction Furnace

This paper will report on the synthesis of bundles of aligned single wall carbon nanotubes (SWCNTs) and multiwall carbon nanotubes (MWCNTs) from palm oil precursor and ferrocene as catalyst source by two stage aerosol-assisted CVD system at various deposition temperature ranging from 700-900oC. Palm oil was pyrolised into the furnace which contained the catalyst source producing black substances at the wall of the reaction furnace which were then collected to be characterized. Field emission scanning electron microscopy equipped with energy dispersive X-ray was used to obtain weight percentage, identification of samples and image of CNTs which showed different structures and diameters of CNTs relative to the deposition temperature of furnace. Raman Spectroscopy was used to further study the quality and identification of samples and finally X-ray powder diffraction was used to determine the crystalinity of samples. Individual micrograph of MWNTs at optimized deposition temperature was also obtained from the high resolution transmission electron microscopy.

Optimization of Chemical Vapor Deposition Synthesis Conditions for Multiwall Carbon Nanotube by Statistical Analysis of Experiment

2008 ◽  
Vol 55-57 ◽  
pp. 533-536
Author(s):  
P. Saiprasert ◽  
D. Koolpiruck ◽  
S. Chiangga
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Multiwall Carbon Nanotubes ◽  
Statistical Design ◽  
Chemical Vapor ◽  
Multiwall Carbon Nanotube ◽  
Synthesis Conditions ◽  
Fourier Transform Raman ◽  
Multiwall Carbon

The optimization of chemical vapor deposition synthesis conditions for multiwall carbon nanotubes (MWCNTs) was experimentally investigated. Carbon nanotubes were grown on cobalt substrate thicknesses of 20, 100 and 1000 nm at 700 and 900 0C with 2 replications. The configuration and morphology of the carbon nanotubes were investigated by scanning electron microscope and Fourier transform raman spectrometer, respectively. The tendency of the parameters was evaluated by statistical design of experiment. Observations on samples produced under our optimised production process, showed that a large number of MWCNTs bundles were produced. Diameter of MWCNTs bundles ranges between 30 and 100 nm throughout the samples. From the variance analysis of the Raman spectra we observe that the thickness of cobalt and temperature of synthesis are highly significant in which the coherence length and innermost diameter increase for either the thickness increases or the temperature decreases.

Atomically Resolved STM Images of CVD Grown Carbon Nanotubes

2004 ◽  
Vol 838 ◽  
Author(s):  
Daniel Chiang ◽  
Philip Zifeng Lei ◽  
Lifeng Dong ◽  
Jun Jiao
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor ◽  
Bimodal Distribution ◽  
Single Wall Carbon Nanotubes ◽  
Scanning Tunneling ◽  
Ambient Conditions ◽  
Chiral Angle ◽  
Index Pairs ◽  
Zero Degree ◽  
Stm Images

ABSTRACTAtomically resolved images of single-wall carbon nanotubes (CNT) grown in a chemical vapor deposition (CVD) chamber were obtained with the scanning tunneling microscope (STM) under ambient conditions. We found that the average diametersdof the CVD-grown CNTs appear to fall into a bimodal distribution of 1.0 and 0.6 nm, and the chiral angle Ø was observed to be close to zero degree. The summation of the lattice indices(n+m)was determined to be 14 and 9 ford=1.0nm andd=0.6nm, respectively. The most possible lattice index pairs(n, m)with a chiral angle close to zero degree are(7, 7)and(5, 4), which indicates that the larger nanotubes are metallic and the smaller nanotubes are semi-conductive.

Electrical Resistance of Single-Wall Carbon Nanotubes with Determined Chiral Indices

2009 ◽  
Vol 1204 ◽  
Author(s):  
Letian Lin ◽  
Lu-Chang Qin ◽  
Sean Washburn ◽  
Scott Paulson
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Vapor Deposition ◽  
Electrical Resistance ◽  
Room Temperature ◽  
Chemical Vapor ◽  
Single Wall Carbon Nanotubes ◽  
Single Wall Carbon ◽  
Transmission Electron ◽  
Highly Sensitive

AbstractThe properties of a carbon nanotube (CNT), in particular a single-wall carbon nanotube (SWNT), are highly sensitive to the atomic structure of the nanotube described by its chirality (chiral indices). We have grown isolated SWNTs on a silicon substrate using chemical vapor deposition (CVD) and patterned sub-micron probes using electron beam lithography. The SWNT was exposed by etching the underlying substrate for transmission electron microscope (TEM) imaging and diffraction studies. For each individual SWNT, its electrical resistance was measured by the four-probe method at room temperature and the chiral indices of the same SWNT were determined by nano-beam electron diffraction. The contact resistances were reduced by annealing to typically 3-5 kΩ. We have measured the I-V curve and determined the chiral indices of each nanotube individually from four SWNTs selected randomly – two are metallic and two are semiconducting. We will present the electrical resistances in correlation with the carbon nanotube diameter as well as the band gap calculated from the determined chiral indices for the semiconducting carbon nanotubes. These experimental results are also discussed in connection with theoretical estimations.

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