Abstract
The elastic modulus of carbyne, a one-dimensional carbon chain, was recently predicted to be much higher than graphene. Inspired by this discovery and the fundamental correlation between elastic modulus and thermal conductivity, we investigate the intrinsic thermal transport in two carbon allotropes: carbyne and cumulene. Using molecular dynamics simulations, we discover that thermal conductivities of carbyne and cumulene at the quantum-corrected room temperature can exceed 54 and 148 kW/m/K, respectively, much higher than that for graphene. Such conductivity is attributed to high phonon energies and group velocities, as well as reduced scattering from non-overlapped acoustic and optical phonon modes. The prolonged spectral acoustic phonon lifetime of 30–110 ps and mean free path of 0.5–2.5 μm exceed those for graphene, and allow ballistic phonon transport along micron-length carbon chains. Tensile extensions can enhance the thermal conductivity of carbyne due to the increased phonon density of states in the acoustic modes and the increased phonon lifetime from phonon bandgap opening. These findings provide fundamental insights into phonon transport and band structure engineering through tensile deformation in low-dimensional materials, and will inspire studies on carbyne, cumulene, and boron nitride chains for their practical deployments in nano-devices.
Highlights
Very recently, ultrahigh elastic modulus was reported, using molecular dynamics (MD) simulations[14] and first-principle calculations[15], for carbyne, an sp-hybridized carbon allotrope which can be viewed as a 1D linear acetylenic carbon chain (Fig. 1(a))
Tensile extensions can enhance the thermal conductivity of carbyne, partially due to the enhanced density of states (DOS) in low-frequency acoustic modes as well as the increased phonon lifetime
Acoustic phonon modes dominate the thermal transport in both carbyne and cumulene, among which the longitudinal acoustic (LA) mode is the primary contributor to the total thermal conductivity
Summary
Ultrahigh elastic modulus was reported, using molecular dynamics (MD) simulations[14] and first-principle calculations[15], for carbyne, an sp-hybridized carbon allotrope which can be viewed as a 1D linear acetylenic carbon chain (Fig. 1(a)). It has been discovered that multi-walled carbon nanotubes (MWCNTs) can serve as reaction capsules to synthesize stable linear carbon chains (up to 100 carbon atoms) embedded in their hollow cylindrical cores[20,21]. Are these atomic chains of fundamental interests in nanoscale phonon transport, but they have many potential applications in ultra-compact nano-electronic/spintronic devices[22,23]. Tensile extensions can enhance the thermal conductivity of carbyne, partially due to the enhanced DOS in low-frequency acoustic modes as well as the increased phonon lifetime
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