Carbon Nanotubes--the Route Toward Applications
02 Aug 2002-Science (American Association for the Advancement of Science)-Vol. 297, Iss: 5582, pp 787-792
TL;DR: Many potential applications have been proposed for carbon nanotubes, including conductive and high-strength composites; energy storage and energy conversion devices; sensors; field emission displays and radiation sources; hydrogen storage media; and nanometer-sized semiconductor devices, probes, and interconnects.
Abstract: Many potential applications have been proposed for carbon nanotubes, including conductive and high-strength composites; energy storage and energy conversion devices; sensors; field emission displays and radiation sources; hydrogen storage media; and nanometer-sized semiconductor devices, probes, and interconnects. Some of these applications are now realized in products. Others are demonstrated in early to advanced devices, and one, hydrogen storage, is clouded by controversy. Nanotube cost, polydispersity in nanotube type, and limitations in processing and assembly methods are important barriers for some applications of single-walled nanotubes.
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TL;DR: In this article, conductive yarns from carbon nanotubes (CNTs) and polyvinyl alcohol (PVA) were prepared by two different methods, wet-spinning and coating processes.
127 citations
TL;DR: Physicochemical methods indicate that the carbon nanoparticles obtained from nanodiamonds (N-CNOs) are smaller and contain more defects than the CNOs obtained from arcing (A-C NOs), which explain the enhanced reactivity of the N-Cnos in cycloaddition and oxidation reactions, as well as in reactions involving radicals.
Abstract: The carbon nanoparticles obtained from either arcing of graphite under water or thermal annealing of nanodiamonds are commonly called carbon nano onions (CNOs), or spherical graphite, as they are made of concentric fullerene cages separated by the same distance as the shells of graphite. A more careful analysis reveals some dramatic differences between the particles obtained by these two synthetic methods. Physicochemical methods indicate that the CNOs obtained from nanodiamonds (N-CNOs) are smaller and contain more defects than the CNOs obtained from arcing (A-CNOs). These properties explain the enhanced reactivity of the N-CNOs in cycloaddition and oxidation reactions, as well as in reactions involving radicals. Given the easier functionalization of the N-CNOs, they are the most obvious choice for studying the potential applications of these multi-shelled fullerenes.
127 citations
01 Jan 2010
TL;DR: A brief history of mechanical computing is provided followed by an overview of the various types of micromechanical switches, with particular emphasis on electromechanical relays since they are among the most promising for IC applications.
Abstract: Power density has grown to be the dominant challenge for continued complementary metal-oxide- semiconductor (CMOS) technology scaling. Together with recent improvements in microrelay design and process tech- nology, this has led to renewed interest in mechanical computing for ultralow-power integrated circuit (IC) applica- tions. This paper provides a brief history of mechanical computing followed by an overview of the various types of micromechanical switches, with particular emphasis on elec- tromechanical relays since they are among the most promising for IC applications. Relay reliability and process integration challenges are discussed. Demonstrations of functional relay logic circuits are then presented, and relay scaling for improved device density and performance is described. Finally, the energy efficiency benefit of a scaled relay technology versus a CMOS technology with comparable minimum dimensions is assessed.
127 citations
Cites background or methods from "Carbon Nanotubes--the Route Toward ..."
...A proper understanding of electromechanical (EM) contact physics, friction, and wear at the nanometer scale is essential for the development of reliable microrelays for RF MEMS [32], active power management [54], and logic applications [ 39 ]....
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...3T electrostatic switches employing carbon nanotubes (CNTs) as the structural electrodes have been proposed [ 39 ] because of their low mass density (� 1g /cm 3 )a nd high Young’s modulus (� 1 TPa) which are beneficial for highspeed operation, as well as their high strength (> 10 GPa) which is beneficial for high endurance....
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TL;DR: In this article, yarn-spinnable and sheet-drawable carbon nanotube forests on highly flexible stainless steel sheets, instead of the conventionally used silicon wafers, were fabricated from the 16 cm maximum demonstrated forest width from both sides of a stainless steel sheet.
127 citations
Cites background from "Carbon Nanotubes--the Route Toward ..."
...[1] Baughman RH, Zakhidov AA, de Heer WA....
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...Individual carbon nanotubes (CNTs) have been long well known to have exceptional mechanical, electronic, photonic, and optical properties, which could provide important applications for both nanoscale devices and macroscopic applications [1]....
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TL;DR: Stable and reproducible photocurrents with monochromatic internal photoconversion efficiency values for H(2)Pc-Py/SWNT as large as 15 and 23% without and with an applied bias of +0.1 V are revealed.
Abstract: In the present work, a new family of pyrene (Py)-substituted phthalocyanines (Pcs), i.e., ZnPc-Py and H2Pc-Py, were designed, synthesized, and probed in light of their spectroscopic properties as well as their interactions with single-wall carbon nanotubes (SWNTs). The pyrene units provide the means for non-covalent functionalization of SWNTs via π−π interactions. Such a versatile approach ensures that the electronic properties of SWNTs are not impacted by the chemical modification of the carbon skeleton. The characterization of ZnPc-Py/SWNT and H2Pc-Py/SWNT has been performed in suspension and in thin films by means of different spectroscopic and photoelectrochemical techniques. Transient absorption experiments reveal photoinduced electron transfer between the photoactive components. ZnPc-Py/SWNT and H2Pc-Py/SWNT have been integrated into photoactive electrodes, revealing stable and reproducible photocurrents with monochromatic internal photoconversion efficiency values for H2Pc-Py/SWNT as large as 15 an...
127 citations
References
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TL;DR: The nanotubes sensors exhibit a fast response and a substantially higher sensitivity than that of existing solid-state sensors at room temperature and the mechanisms of molecular sensing with nanotube molecular wires are investigated.
Abstract: Chemical sensors based on individual single-walled carbon nanotubes (SWNTs) are demonstrated. Upon exposure to gaseous molecules such as NO 2 or NH 3 , the electrical resistance of a semiconducting SWNT is found to dramatically increase or decrease. This serves as the basis for nanotube molecular sensors. The nanotube sensors exhibit a fast response and a substantially higher sensitivity than that of existing solid-state sensors at room temperature. Sensor reversibility is achieved by slow recovery under ambient conditions or by heating to high temperatures. The interactions between molecular species and SWNTs and the mechanisms of molecular sensing with nanotube molecular wires are investigated.
5,908 citations
TL;DR: In this paper, the fabrication of a three-terminal switching device at the level of a single molecule represents an important step towards molecular electronics and has attracted much interest, particularly because it could lead to new miniaturization strategies in the electronics and computer industry.
Abstract: The use of individual molecules as functional electronic devices was first proposed in the 1970s (ref 1) Since then, molecular electronics2,3 has attracted much interest, particularly because it could lead to conceptually new miniaturization strategies in the electronics and computer industry The realization of single-molecule devices has remained challenging, largely owing to difficulties in achieving electrical contact to individual molecules Recent advances in nanotechnology, however, have resulted in electrical measurements on single molecules4,5,6,7 Here we report the fabrication of a field-effect transistor—a three-terminal switching device—that consists of one semiconducting8,9,10 single-wall carbon nanotube11,12 connected to two metal electrodes By applying a voltage to a gate electrode, the nanotube can be switched from a conducting to an insulating state We have previously reported5 similar behaviour for a metallic single-wall carbon nanotube operated at extremely low temperatures The present device, in contrast, operates at room temperature, thereby meeting an important requirement for potential practical applications Electrical measurements on the nanotube transistor indicate that its operation characteristics can be qualitatively described by the semiclassical band-bending models currently used for traditional semiconductor devices The fabrication of the three-terminal switching device at the level of a single molecule represents an important step towards molecular electronics
5,258 citations
TL;DR: X-ray diffraction and electron microscopy showed that fullerene single-wall nanotubes (SWNTs) are nearly uniform in diameter and that they self-organize into “ropes,” which consist of 100 to 500 SWNTs in a two-dimensional triangular lattice with a lattice constant of 17 angstroms.
Abstract: The major part of this chapter has already appeared in [1], but because of the length restrictions (in Science), the discussion on why we think this form is given in only brief detail. This chapter goes into more depth to try to answer the questions of why the fullerenes form themselves. This is another example of the very special behavior of carbon. From a chemist’s standpoint, it is carbon’s ability to form multiple bonds that allows it to make these low dimensional forms rather than to produce tetrahedral forms. Carbon can readily accomplish this and it is in the mathematics and physics of the way this universe was put together, that carbon is given this property. One of the consequences of this property is that, if left to its own devices as carbon condenses from the vapor and if the temperature range is just right, above 1000°C, but lower than 1400°C, there is an efficient self-assembly process whose endpoint is C60.
5,215 citations
TL;DR: In this paper, the Young's modulus, strength, and toughness of nanostructures are evaluated using an atomic force microscopy (AFM) approach. And the results showed that the strength of the SiC NRs were substantially greater than those found previously for larger SiC structures, and they approach theoretical values.
Abstract: The Young's modulus, strength, and toughness of nanostructures are important to proposed applications ranging from nanocomposites to probe microscopy, yet there is little direct knowledge of these key mechanical properties. Atomic force microscopy was used to determine the mechanical properties of individual, structurally isolated silicon carbide (SiC) nanorods (NRs) and multiwall carbon nanotubes (MWNTs) that were pinned at one end to molybdenum disulfide surfaces. The bending force was measured versus displacement along the unpinned lengths. The MWNTs were about two times as stiff as the SiC NRs. Continued bending of the SiC NRs ultimately led to fracture, whereas the MWNTs exhibited an interesting elastic buckling process. The strengths of the SiC NRs were substantially greater than those found previously for larger SiC structures, and they approach theoretical values. Because of buckling, the ultimate strengths of the stiffer MWNTs were less than those of the SiC NRs, although the MWNTs represent a uniquely tough, energy-absorbing material.
4,627 citations
TL;DR: The thermal conductivity and thermoelectric power of a single carbon nanotube were measured using a microfabricated suspended device and shows linear temperature dependence with a value of 80 microV/K at room temperature.
Abstract: The thermal conductivity and thermoelectric power of a single carbon nanotube were measured using a microfabricated suspended device. The observed thermal conductivity is more than 3000 W/K m at room temperature, which is 2 orders of magnitude higher than the estimation from previous experiments that used macroscopic mat samples. The temperature dependence of the thermal conductivity of nanotubes exhibits a peak at 320 K due to the onset of umklapp phonon scattering. The measured thermoelectric power shows linear temperature dependence with a value of 80 microV/K at room temperature.
3,166 citations