Ballistic- and quantum-conductor carbon nanotubes: A reference experiment put to the test

Kobylko, Mathias; Kociak, Mathieu; Sato, Yuta; Urita, Koki; Bonnot, A.M.; Kasumov, A.; Kasumov, Yu. A.; Suenaga, Kazu; Colliex, C.

doi:10.1103/physrevb.90.195431

Cited by 9 publications

(4 citation statements)

References 37 publications

(76 reference statements)

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“…Unexpectedly however, similar results were shown for several different materials [11,12], and even for lower quality CNTs made in CVD processes [13]. A serious flaw in the method was later revealed, showing that the nanotubes may not actually penetrate the Mercury liquid, but instead the surface of the Mercury is deformed [14][15][16]. The small changes in resistance would then merely reflect resistance changes at the same fixed contact point as the pressure towards the liquid surface was varied [14].…”

Section: Introductionmentioning

confidence: 64%

Accurate determination of electrical conductance in carbon nanostructures

Flygare

Svensson

2022

Mater. Res. Express

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Electrical characterization of nanostructures, such as nanotubes and wires, is a demanding task that is vital for future applications of nanomaterials. The nanostructures should ideally be analyzed in a free-standing state and also allow for other material characterizations to be made of the same individual nanostructures. Several methods have been used for electrical characterizations of carbon nanotubes in the past. The results are widely spread, both between different characterizations methods and within the same materials. This raises questions regarding the reliability of different methods and their accuracy, and there is a need for a measurement standard and classification scheme for carbon nanotube materials. Here we examine a two-probe method performed inside a transmission electron microscope in detail, addressing specifically the accuracy by which the electrical conductivity of individual carbon nanotubes can be determined. We show that two-probe methods can be very reliable using a suitable thermal cleaning method of the contact points. The linear resistance of the outermost nanotube wall can thus be accurately determined even for the highest crystallinity materials, where the linear resistance is only a few kΩ/μm. The method can thereby by used as a valuable tool for future classification schemes of various nanotube material classes.

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Section: Introductionmentioning

confidence: 64%

Accurate determination of electrical conductance in carbon nanostructures

Flygare

Svensson

2022

Mater. Res. Express

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“…However, the reliability of these measurements has been strongly criticized. Studies [40,41] argued that the used liquid-metal contact method gives "false positive" results for the ballistic nature of conductance. The theory of quantum resistance assumes the absence of the CNT structural defects.…”

Section: Introductionmentioning

confidence: 99%

Uncertainties in Electric Circuit Analysis of Anisotropic Electrical Conductivity and Piezoresistivity of Carbon Nanotube Nanocomposites

2022

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Electrical conductivity and piezoresistivity of carbon nanotube (CNT) nanocomposites are analyzed by nodal analysis for aligned and random CNT networks dependent on the intrinsic CNT conductivity and tunneling barrier values. In the literature, these parameters are assigned with significant uncertainty; often, the intrinsic resistivity is neglected. We analyze the variability of homogenized conductivity, its sensitivity to deformation, and the validity of the assumption of zero intrinsic resistivity. A fast algorithm for simulation of a gauge factor is proposed. The modelling shows: (1) the uncertainty of homogenization caused by the uncertainty in CNT electrical properties is higher than the uncertainty, caused by the nanocomposite randomness; (2) for defect-prone nanotubes (intrinsic conductivity ~104 S/m), the influence of tunneling barrier energy on both the homogenized conductivity and gauge factor is weak, but it becomes stronger for CNTs with higher intrinsic conductivity; (3) the assumption of infinite intrinsic conductivity (defect-free nanotubes) has strong influence on the homogenized conductivity.

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“…Both parameters are measurable by experiments. 2,3 At the mesoscopic level, the distribution and geometry of the embedded CNTs in a polymer matrix are crucial for the overall conductivity. The possibility of percolating pathways depends not only on the manufacturing of the CNTs itself but also on the manufacturing process of the composite like infusion or printing of CNRP as well as intentionally set conditions like externally applied electric or magnetic fields 2 that are influencing the orientation.…”

Section: Introductionmentioning

confidence: 99%

Effects of curvature and alignment of carbon nanotubes on the electrical conductivity of carbon nanotube-reinforced polymers investigated by mesoscopic simulations

Bartels

Jürgens

Kuhn

et al. 2018

Journal of Composite Materials

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Carbon nanotube-reinforced polymers belong to a class of composite materials, which have been largely investigated due to their special electrical, thermal and mechanical properties. In the case of electrical conductivity of carbon nanotube-reinforced polymer, a critical amount of carbon nanotubes as a filler material enables a sharp increase of electrical conductivity. At this certain volume fraction of carbon nanotubes, the material turns into a conductor because of the percolation effect. This effect occurs due to the formation of a closed pathway of filler material through the system. Mesoscopic simulation models of these materials were carried out to predict their electrical conductivity. In this paper, the effects of carbon nanotube curvature and their alignment parallel or perpendicular to the electrical flow direction inside a representative volume element were analysed and an optimized carbon nanotube distribution is presented. A network with a longest average path length per (rigid) carbon nanotube but also cross-linking (only nearly isotropic alignment) shows the best conductivity in the preferred direction.

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Ballistic- and quantum-conductor carbon nanotubes: A reference experiment put to the test

Abstract: International audienc

Cited by 9 publications

References 37 publications

Accurate determination of electrical conductance in carbon nanostructures

Accurate determination of electrical conductance in carbon nanostructures

Uncertainties in Electric Circuit Analysis of Anisotropic Electrical Conductivity and Piezoresistivity of Carbon Nanotube Nanocomposites

Effects of curvature and alignment of carbon nanotubes on the electrical conductivity of carbon nanotube-reinforced polymers investigated by mesoscopic simulations

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