Abstract
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%.
Highlights
Nanotechnology holds potential for miniaturization, densification, and increasing device performance and for changing nanometer-scale physical properties and creating products with novel functions [1]
carbon nanocoil (CNC) purity is still low in the carbon deposits as a whole, and improving the CNC
We attempted to reduce the compositional ratio of the carbon layer, which does not contain CNCs, to the CNC layer and performed CVD experiments
Summary
Nanotechnology holds potential for miniaturization, densification, and increasing device performance and for changing nanometer-scale physical properties and creating products with novel functions [1]. In 1990, Motojima et al [6] synthesized carbon microcoil (CMC), which is a regular-shaped helical carbon fiber, via catalytic chemical vapor deposition (CCVD) using a Ni catalyst-coated graphite substrate and feedstock gases (C2H2, H2, N2, and C4H4S). Sn liquid solution mixed with Fe powder on a graphite substrate [43,44] Using this method, the CNC purity on the surface of the deposits reached almost 100%. There was a carbon layer that did not contain CNCs between the upper and lower CNC layers; this was called the carbon layer Both the CNC and carbon layers were grown from a catalyst that was deposited on the substrate. We attempted to reduce the thickness of the catalyst layer by using a spin-coating method and Fe fine powder to increase the CNC yield and purity.
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