title: Thermal Diffusivity of a Single Carbon Nanocoil: Uncovering the Correlation with Temperature and Domain Size.
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 × 104× e-d/37.7+ 9.5) × 10-7m2/s. Combined with the Raman-based grain size (La) characterization, α and Laare correlated as α = [81.2 × (La- 3.32)1.5+ 9.5] × 10-7m2/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-1) 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, La, and α.
authors.affiliation: School of Physics and Optoelectronic Technology, Dalian University of Technology , No. 2 Linggong Road, Ganjingzi District, Dalian 116024, People's Republic of China.|Department of Mechanical Engineering, Iowa State University , 2010 Black Engineering Building, Ames, Iowa 50011, United States.
authors.forename: Chenghao
authors.initials: C
authors.lastname: Deng
authors.affiliation: School of Physics and Optoelectronic Technology, Dalian University of Technology , No. 2 Linggong Road, Ganjingzi District, Dalian 116024, People's Republic of China.|College of Electronic Science and Technology, Shenzhen University , No. 3688 Nanhai Avenue, Shenzhen 518060, People's Republic of China.
authors.forename: Yanming
authors.initials: Y
authors.lastname: Sun
authors.affiliation: School of Physics and Optoelectronic Technology, Dalian University of Technology , No. 2 Linggong Road, Ganjingzi District, Dalian 116024, People's Republic of China.
authors.forename: Lujun
authors.initials: L
authors.lastname: Pan
authors.affiliation: Department of Mechanical Engineering, Iowa State University , 2010 Black Engineering Building, Ames, Iowa 50011, United States.
authors.forename: Tianyu
authors.initials: T
authors.lastname: Wang
authors.affiliation: Department of Mechanical Engineering, Iowa State University , 2010 Black Engineering Building, Ames, Iowa 50011, United States.
authors.forename: Yangsu
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Department of Mechanical Engineering, Iowa State University , 2010 Black Engineering Building, Ames, Iowa 50011, United States.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Mechanical Engineering, Iowa State University , 2010 Black Engineering Building, Ames, Iowa 50011, United States.
authors.forename: Bowen
authors.initials: B
authors.lastname: Zhu
authors.affiliation: Department of Mechanical Engineering, Iowa State University , 2010 Black Engineering Building, Ames, Iowa 50011, United States.
authors.forename: Xinwei
authors.initials: X
authors.lastname: Wang
keywords: carbon nanocoil; domain size; specific heat; thermal conductivity; thermal diffusivity