Browsing by Author "Young, Colin C."

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    Carbon nanotube fiber terahertz polarizer
    (AIP Publishing, 2016) Zubair, Ahmed; Tsentalovich, Dmitri E.; Young, Colin C.; Heimbeck, Martin S.; Everitt, Henry O.; Pasquali, Matteo; Kono, Junichiro
    Conventional, commercially available terahertz (THz) polarizers are made of uniformly and precisely spaced metallic wires. They are fragile and expensive, with performance characteristics highly reliant on wire diameters and spacings. Here, we report a simple and highly error-tolerant method for fabricating a freestanding THz polarizer with nearly ideal performance, reliant on the intrinsically one-dimensional character of conduction electrons in well-aligned carbon nanotubes(CNTs). The polarizer was constructed on a mechanical frame over which we manually wound acid-doped CNT fibers with ultrahigh electrical conductivity. We demonstrated that the polarizer has an extinction ratio of ∼−30 dB with a low insertion loss (<0.5 dB) throughout a frequency range of 0.2–1.1 THz. In addition, we used a THzellipsometer to measure the Müller matrix of the CNT-fiber polarizer and found comparable attenuation to a commercial metallic wire-grid polarizer. Furthermore, based on the classical theory of light transmission through an array of metallic wires, we demonstrated the most striking difference between the CNT-fiber and metallic wire-grid polarizers: the latter fails to work in the zero-spacing limit, where it acts as a simple mirror, while the former continues to work as an excellent polarizer even in that limit due to the one-dimensional conductivity of individual CNTs.
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    High-Ampacity Power Cables of Tightly-Packed and Aligned Carbon Nanotubes
    (Wiley, 2014) Wang, Xuan; Behabtu, Natnael; Young, Colin C.; Tsentalovich, Dmitri E.; Pasquali, Matteo; Kono, Junichiro; Richard E. Smalley Institute for Nanoscale Science and Technology
    The current-carrying capacity (CCC), or ampacity, of highly-conductive, light, and strong carbon nanotube (CNT) fibers is characterized by measuring their failure current density (FCD) and continuous current rating (CCR) values. It is shown, both experimentally and theoretically, that the CCC of these fibers is determined by the balance between current-induced Joule heating and heat exchange with the surroundings. The measured FCD values of the fibers range from 107 to 109 A m−2 and are generally higher than the previously reported values for aligned buckypapers, carbon fibers, and CNT fibers. To the authors’ knowledge, this is the first time the CCR for a CNT fiber has been reported. The specific CCC value (i.e., normalized by the linear mass density) of these CNT fibers are demonstrated to be higher than those of copper.
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    Strong, Light, Multifunctional Fibers of Carbon Nanotubes with Ultrahigh Conductivity
    (AAAS, 2013) Behabtu, Natnael; Young, Colin C.; Tsentalovich, Dmitri E.; Kleinerman, Olga; Wang, Xuan; Ma, Anson W.K.; Bengio, E. Amram; ter Waarbeek, Ron F.; de Jong, Jorrit J.; Hoogerwerf, Ron E.; Fairchild, Steven B.; Ferguson, John B.; Maruyama, Benji; Kono, Junichiro; Talmon, Yeshayahu; Cohen, Yachin; Otto, Marcin J.; Pasquali, Matteo; Richard E. Smalley Institute for Nanoscale Science and Technology
    Broader applications of carbon nanotubes to real-world problems have largely gone unfulfilled because of difficult material synthesis and laborious processing. We report high-performance multifunctional carbon nanotube (CNT) fibers that combine the specific strength, stiffness, and thermal conductivity of carbon fibers with the specific electrical conductivity of metals. These fibers consist of bulk-grown CNTs and are produced by high-throughput wet spinning, the same process used to produce high-performance industrial fibers. These scalable CNT fibers are positioned for high-value applications, such as aerospace electronics and field emission, and can evolve into engineered materials with broad long-term impact, from consumer electronics to long-range power transmission.