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11.01.2012

Nature Materials | Letter


Thermal conductivity of isotopically modified graphene





Journal name:

Nature Materials

Year published:

(2012)

DOI:

doi:10.1038/nmat3207


Received


Accepted


Published online


In addition to its exotic electronic properties1, 2 graphene exhibits unusually high intrinsic thermal conductivity3, 4, 5, 6. The physics of phonons—the main heat carriers in graphene—has been shown to be substantially different in two-dimensional (2D) crystals, such as graphene, from in three-dimensional (3D) graphite7, 8, 9, 10. Here, we report our experimental study of the isotope effects on the thermal properties of graphene. Isotopically modified graphene containing various percentages of 13C were synthesized by chemical vapour deposition (CVD). The regions of different isotopic compositions were parts of the same graphene sheet to ensure uniformity in material parameters. The thermal conductivity, K, of isotopically pure 12C (0.01% 13C) graphene determined by the optothermal Raman technique3, 4, 5, 6, 7, 10, was higher than 4,000 W mK−1 at the measured temperature Tm~320 K, and more than a factor of two higher than the value of K in graphene sheets composed of a 50:50 mixture of 12C and 13C. The experimental data agree well with our molecular dynamics (MD) simulations, corrected for the long-wavelength phonon contributions by means of the Klemens model. The experimental results are expected to stimulate further studies aimed at a better understanding of thermal phenomena in 2D crystals.




Figures at a glance


left


  1. Figure 1: Micro-Raman characteristics of the isotopically modified graphene.


    a, Raman map (2,530~2,730 cm−1) of the 2D bands. The colour bar shown below indicates the dosing sequence for the four regions. b, Raman spectra of graphene measured at the positions labelled by the coloured circles in a. c, SEM image of graphene transferred onto the SiNx holey membrane. d, Raman maps of graphene transferred onto the SiNx holey membrane. From left to right, three Raman maps showing the integrated intensity of the 2D band of 0.01% 13C (2,630~2,730 cm−1), the 50:50 12C/13C mixture (2,560~2,660 cm−1) and 99.2% 13C (2,530~2,630 cm−1) graphene, respectively. The x-axis shows counts (cts) from the CCD (charge-coupled device). The arrows indicate wrinkles and cracks in some samples, which were excluded from the thermal measurements.





  2. Figure 2: Thermal conductivity K of the suspended graphene film with 13C isotope concentrations of 0.01%, 1.1% (natural abundance), 50% and 99.2%, respectively, as a function of the temperature measured with the micro-Raman spectrometer.


    The solid lines are a guide to the eye only. The experimental errors were estimated by means of the square-root-sum error propagation approach, including the following error sources: the Raman peak position calibration, temperature resolution of the Raman measurement method, and the uncertainty of the laser absorption.





  3. Figure 3: Thermal conductivity of graphene as a function of its isotopic composition.


    a, Histograms of K for graphene films with 0.01%, 1.1%, 50% and 99.2% 13C isotopic concentration at ~380 K. The solid lines represent fits to the experimental data with the normal distribution. b, The average value of the measured thermal conductivity K as a function of 13C concentration at ~380 K. The MD simulations results for K are shown as yellow squares for comparison.












 



ftp://ihim.uran.ru/localfiles/NM/nmat3207.pdf


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А Б В Г Д Е Ё Ж З И Й К Л М Н О П Р С Т У Ф Х Ц Ч Ш Щ Ъ Ы Ь Э Ю Я
  • Chen Wev .  honorary member of ISSC science council

  • Harton Vladislav Vadim  honorary member of ISSC science council

  • Lichtenstain Alexandr Iosif  honorary member of ISSC science council

  • Novikov Dimirtii Leonid  honorary member of ISSC science council

  • Yakushev Mikhail Vasilii  honorary member of ISSC science council

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