Abstract
Based on first-principles calculations and full iterative solution of the linearized Boltzmann-Peierls transport equation for phonons, we systematically investigate effects of strain, size and temperature on the thermal conductivity k of suspended graphene. The calculated size-dependent and temperature-dependent k for finite samples agree well with experimental data. The results show that, contrast to the convergent room-temperature k = 5450 W/m-K of unstrained graphene at a sample size ∼8 cm, k of strained graphene diverges with increasing the sample size even at high temperature. Out-of-plane acoustic phonons are responsible for the significant size effect in unstrained and strained graphene due to their ultralong mean free path and acoustic phonons with wavelength smaller than 10 nm contribute 80% to the intrinsic room temperature k of unstrained graphene. Tensile strain hardens the flexural modes and increases their lifetimes, causing interesting dependence of k on sample size and strain due to the competition between boundary scattering and intrinsic phonon-phonon scattering. k of graphene can be tuned within a large range by strain for the size larger than 500 μm. These findings shed light on the nature of thermal transport in two-dimensional materials and may guide predicting and engineering k of graphene by varying strain and size.
Original language | English |
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Pages (from-to) | 772-778 |
Number of pages | 7 |
Journal | International Journal of Heat and Mass Transfer |
Volume | 101 |
DOIs | |
State | Published - Oct 1 2016 |
Funding
We are thankful for the financial support from the Hong Kong General Research Fund under Grant Nos. 623212 , 613413 and 152140/14E , the Hong Kong Polytechnic University under Grant No. 1-99QP and the National Natural Science Foundation of China under Grant No. 51271157 . L.L. acknowledges support from the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division and the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility supported by the Office of Science of the U. S. Department of Energy under Contract No. DE-AC02-05CH11231 .
Funders | Funder number |
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Hong Kong General Research Fund | 623212, 152140/14E, 613413 |
U.S. Department of Energy | DE-AC02-05CH11231 |
Office of Science | |
Basic Energy Sciences | |
Division of Materials Sciences and Engineering | |
National Natural Science Foundation of China | 51271157 |
Hong Kong Polytechnic University | 1-99QP |
Keywords
- First principles
- Graphene
- Phonon thermal transport
- Strain and size effects