Thermal Diffusivity of a Single Carbon Nanocoil: Uncovering the Correlation with Temperature and Domain Size.

ACS Nano

Department of Mechanical Engineering, Iowa State University, 2010 Black Engineering Building, Ames, Iowa 50011, United States.

Published: October 2016

AI Article Synopsis

  • Carbon nanocoils (CNCs) have unique helical structures and polycrystalline-amorphous characteristics, which lead to different energy transport properties compared to carbon nanotubes and graphene, making them useful in various applications.
  • A study of thermal diffusivity (α) and conductivity (κ) from 290 K to 10 K shows that α correlates with line diameter and grain size, with α increasing as temperature decreases, while κ has a peak around 75 K.
  • The thermal reffusivity (Θ) of CNCs decreases linearly with temperature, contrasting with the exponential decrease seen in graphite and graphene foam, indicating unique structural characteristics that align with X-ray diffraction and Raman spectroscopy findings.

Article Abstract

The helical geometries and polycrystalline-amorphous structure of carbon nanocoils (CNCs), an exotic class of low-dimensional carbon nanostructures, distinguish them from carbon nanotubes and graphene. These distinct structures result in very different energy transport from that in carbon nanotubes and graphene, leading to important roles in applications as wave absorbers, near-infrared sensors, and nanoelectromechanical sensors. Here we report a systematic study of the thermal diffusivity (α) and conductivity (κ) of CNCs from 290 to 10 K and uncover their property-structure aspects. Our room-temperature α study reveals a correlation between α and the line diameter (d): α = (5.43 × 10 × e + 9.5) × 10 m/s. Combined with the Raman-based grain size (L) characterization, α and L are correlated as α = [81.2 × (L - 3.32) + 9.5] × 10 m/s. With temperature decreasing from 290 K to 10 K, α has a 1-1.6-fold increase, and κ shows a peak around 75 K. To best understand the defect level and polycrystalline-amorphous structure of CNCs, the thermal reffusivity (Θ = α) of CNCs is studied and compared with that of graphite and graphene foam from 290 K down to 10 K. Very interestingly, CNC's Θ linearly decreases with decreased temperature, while Θ of graphite and graphene foam have an exponential decrease. The extrapolated 0 K-limit Θ is determined by low-momentum phonon scattering and gives a structure domain size of CNC samples (d = 455, 353, and 334 nm) of 1.28, 2.03 and 3.24 nm. These sizes are coherent with the X-ray diffraction results (3.5 nm) and the Raman spectroscopy study and confirm the correlation among d, L, and α.

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http://dx.doi.org/10.1021/acsnano.6b05715DOI Listing

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