Effect of purification of the electrical conductivity and complex permittivity of multiwall carbon nanotubes

Grimes, Craig A.; Dickey, Elizabeth C.; Mungle, Casey; Ong, Keat Ghee; Qian, Dali

doi:10.1063/1.1400100

Cited by 125 publications

(83 citation statements)

References 28 publications

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“…In fact, the extracted real parts of permeability µ r ' for the papers ranged from 0.7 to 1.5. Figure 6 summarizes ε r ' as a function of frequency for our composites along with those reported in the literature [24,30,[34][35][36]54,[65][66][67][68][69][70][71][72][73][74][75]. Our composite papers are among the highest in the microwave region.…”

Section: Resultsmentioning

confidence: 81%

“…The effective permittivities of composites have been evaluated with effective medium theories (EMTs), such as the Maxwell-Garnett formula. Grimes et al [65] successfully reproduced their experimental permittivity of MWCNT/polystyrene composites with an EMT modified by Lagarkov and Sarychev [76]. We tried to reproduce the measured data with the Lagarkov-Sarychev, Maxwell-Garnett, and Bruggeman formulae but unfortunately did not succeed.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Highly strong and conductive carbon nanotube/cellulose composite paper

Imai¹,

Akiyama²,

Tomo

et al. 2010

Composites Science and Technology

127

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Carbon nanotube (CNT)/cellulose composite materials were fabricated in a paper making process optimized for a CNT network to form on the cellulose fibers. The measured electric conductivity was from 0.05-671 S/m for 0.5-16.7-wt% CNT content, higher than that for other polymer composites. The real permittivities were the highest in the microwave region. The unique CNT network structure is thought to be the reason for these high conductivity and permittivity values. Compared to other carbon materials, our carbon CNT/cellulose composite material had improved parameters without decreased mechanical strength. The near-field electromagnetic shielding effectiveness (EMI SE) measured by a microstrip line method depended on the sheet conductivity and qualitatively matched the results of electromagnetic field simulations using a finite-difference time-domain simulator. A high near-field EMI SE of 50-dB was achieved in the 5-10 GHz frequency region with 4.8-wt% composite paper. The far-field EMI SE was measured by a free space method. Fairly good agreement was obtained between the measured and calculated results. Approximately 10-wt% CNT is required to achieve composite paper with 20-dB far-field EMI SE.

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Section: Resultsmentioning

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Highly strong and conductive carbon nanotube/cellulose composite paper

Imai¹,

Akiyama²,

Tomo

et al. 2010

Composites Science and Technology

127

View full text Add to dashboard Cite

show abstract

“…Assuming that the MWNT is a long prolate spheroid with the longest axis aligned with the electric field, the induced dipole moment is (2) where and are absolute permittivity of the medium, the half-length of the MWNT, and the radius of the MWNT, respectively. Therefore, the complex polarization factor is given by (3) where and are the absolute complex permittivities of the MWNT [21] and the medium (ethanol) [22], respectively, and the approximated depolarization factor [20] . Since the electric-field components are in-phase, the time-averaged DEP force deduced from the above equations is (4) where is the gradient of the square of the root mean square (rms) of the electric field.…”

Section: A Theoretical Background and Modelingmentioning

confidence: 99%

Dielectrophoretic Batch Fabrication of Bundled Carbon Nanotube Thermal Sensors

Fung

Wong

Chan

et al. 2004

IEEE Trans. Nanotechnology

114

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Abstract-We present a feasible technology for batch assembly of carbon nanotube (CNT) devices by utilizing ac electrophoretic technique to manipulate multiwalled bundles on an Si/SiO 2 substrate. Based on this technique, CNTs were successfully and repeatably manipulated between microfabricated electrodes. By using this parallel assembly process, we have investigated the possibility of batch fabricating functional CNT devices when an ac electrical field is applied to an array of microelectrodes that are electrically connected together. Preliminary experimental results showed that over 70% of CNT functional devices can be assembled successfully using our technique, which is considered to be a good yield for nanodevices manufacturing. Besides, the devices were demonstrated to potentially serve as novel thermal sensors with low power consumption ( microwatts) with electronic circuit response of approximately 100 kHz in constant current mode operation. In this paper, we will present the fabrication process of this feasible batch manufacturable method for functional CNT-based thermal sensors, which will dramatically reduce production costs and production time of nanosensing devices and potentially enable fully automated assembly of CNT-based devices. Experimental results from the thermal sensors fabricated by this batch process will also be discussed.Index Terms-AC electrophoretic manipulation, carbon nanotube (CNT), CNT sensors, nano batch fabrication, nanomanufacturing.

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“…Nevertheless, the electrical characterization of carbon nanotube networks can be challenging because it usually requires special preparation of either a thin film or embedding CNTs into a host medium which decreases the accuracy of extracted complex permittivity. The effects of a sample preparation are difficult to characterize which explains the variations of the extracted permittivity previously reported in [6]- [7]. EL Sabbagh et al present a technique of extraction based on planar transmission line measurements where the metallic trace of the transmission line is replaced by CNT networks [8].…”

Section: Introductionmentioning

confidence: 99%

Rigorous Characterization of Carbon Nanotube Complex Permittivity Over a Broadband of RF Frequencies

Decrossas

Sabbagh

Hanna

et al. 2012

IEEE Trans. Electromagn. Compat.

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Abstract-Thiswork presents a comprehensive characterization of the frequency dependence of the effective complex permittivity of bundled carbon nanotubes considering different densities over a broadband of frequencies from 10 MHz to 50 GHz using only one measurement setup. The extraction technique is based on rigorous modeling of coaxial and circular discontinuities using mode matching technique in conjunction with inverse optimization method to map the simulated scattering parameters to those measured by vector network analyzer. The dramatic values of complex permittivity obtained at low frequencies are physically explained by the percolation theory. The effective permittivity of a mixture of nano-particles of alumina and carbon nanotubes versus frequency and packing density is studied to verify the previously obtained phenomenon.

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Effect of purification of the electrical conductivity and complex permittivity of multiwall carbon nanotubes

Cited by 125 publications

References 28 publications

Highly strong and conductive carbon nanotube/cellulose composite paper

Highly strong and conductive carbon nanotube/cellulose composite paper

Dielectrophoretic Batch Fabrication of Bundled Carbon Nanotube Thermal Sensors

Rigorous Characterization of Carbon Nanotube Complex Permittivity Over a Broadband of RF Frequencies

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