Magnetoresistance in carbon micro-coils annealed at various temperatures

Fujii, M.; Matsui, Makoto; Motojima, Seiji; Hishikawa, Yukio

doi:10.1016/s0022-0248(01)02254-0

Cited by 31 publications

(22 citation statements)

References 11 publications

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“…They are also used in nanosprings [26][27][28][29][30], electrode materials in fuel cells [31][32][33][34], field emitters [35][36][37], magnetic sensors [38,39], and various industrial fields [40][41][42].…”

Section: Catalystmentioning

confidence: 99%

High-Yield Synthesis of Helical Carbon Nanofibers Using Iron Oxide Fine Powder as a Catalyst

et al. 2015

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Carbon nanocoil (CNC), which is synthesized by a catalytic chemical vapor deposition (CCVD) method, has a coil diameter of 300-900 nm and a length of several tens of μm. Although it is very small, CNC is predicted to have a high mechanical strength and hence is expected to have a use in nanodevices such as electromagnetic wave absorbers and field emitters. For nanodevice applications, it is necessary to synthesize CNC in high yield and purity. In this study, we improved the conditions of catalytic layer formation and CCVD. Using optimized CVD conditions, a CNC layer with a thickness of >40 μm was grown from a SnO2/Fe2O3/SnO2 catalyst on a substrate, and its purity increased to 81% ± 2%.

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Section: Catalystmentioning

confidence: 99%

High-Yield Synthesis of Helical Carbon Nanofibers Using Iron Oxide Fine Powder as a Catalyst

et al. 2015

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“…These helical carbon filaments have lower electrical conductivities than pyrolytic graphite (2000-4000 S/cm) [51], and b-DHCFs generally have a lower electrical conductivity than t-SHCFs because of their crystallinities ( Figure 5) [6,19,24,28]. Fujii et al [52] reported that the electrical conductivity of double helical CMCs increased about 10-fold by heat treatment for 6 h at 3000 °C in Ar atmosphere. As shown in Figure 17, heat treated CMCs at 3000 °C were well graphitized [24].…”

Section: Electrical Propertiesmentioning

confidence: 99%

Growth and Properties of Carbon Microcoils and Nanocoils

2014

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Abstract:Various types of coiled carbon filaments have been synthesized using chemical vapor deposition and other methods. These carbon filaments exhibit unique electrical and mechanical properties due to their versatile shapes and structures. To form coiled shapes, different types of catalyst compositions and reactive gases have been explored. Generally, coiled carbon filaments are classified by coil diameter and shape (e.g., microcoil and nanocoil). In this review, coiled carbon filaments are classified into three growth mechanism categories: (1) bidirectional double helical growth; (2) bidirectional twisted growth; and (3) tip single helical or twisted growth. Next, their synthesis methods and hypothetical growth mechanisms are discussed. Then, their electrical and mechanical properties are listed. Finally, potential applications and uses of coiled carbon filament are mentioned.

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“…3.3.4 Electromagnetic Properties: [21][22][23][24] It is considered that the CMCs are promising candidates for use as EM absorbers, especially in the gigahertz (GHz) range, because of its micro-coiling morphology. In other word, the micro-coiling morphology is the most effective and ideal morphology for the generation of an inductive current by Faraday's Law resulting in absorption of EM wave.…”

Section: Electric Propertiesmentioning

confidence: 99%

Preparation and Characterization of Carbon Microcoils (CMCs)

Motojima

Chen

2007

Bulletin of the Chemical Society of Japan

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Carbon micro-coils (CMCs) with 3D-helical/spiral structures and coil diameters on the order of micrometer were obtained by metal-catalyzed pyrolysis of acetylene at 700-800 C. The preparation conditions, morphology, growth mechanism, microstructure, and some properties of the CMCs were examined in detail. Two pieces of vapor grown carbon fibers grown from a metal catalyst grain curl and entwine each other due to the anisotropic catalytic activity between different crystal faces of the catalyst grain and thus form double-helix CMCs. CMCs have an almost amorphous structure but could be graphitized by high-temperature heat treatment with full preservation of the coiling morphology. The CMCs could effectively generate inductive electromotive force, inductive current and thus Joul's heat under microwave irradiation. The CMCs/elastic polymer composite elements showed high tactile sensing properties which are comparable to that of human skin. The CMCs are a possible candidate for electromagnetic wave absorbers, remote heating materials, visualization elements of microwaves, tactile sensor elements, micro-antennae, chiral catalysts, bio-activators or biodeactivators, energy converters, etc.

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Magnetoresistance in carbon micro-coils annealed at various temperatures

Cited by 31 publications

References 11 publications

High-Yield Synthesis of Helical Carbon Nanofibers Using Iron Oxide Fine Powder as a Catalyst

High-Yield Synthesis of Helical Carbon Nanofibers Using Iron Oxide Fine Powder as a Catalyst

Growth and Properties of Carbon Microcoils and Nanocoils

Preparation and Characterization of Carbon Microcoils (CMCs)

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