SENSITIVITY OF THERMAL CONDUCTIVITY OF CARBON NANOTUBES TO DEFECT CONCENTRATIONS AND HEAT-TREATMENT
MFP Bifano and J Park and V Prakash, INTERNATIONAL MECHANICAL ENGINEERING CONGRESS AND EXPOSITION - 2012, VOL 9, PTS A AND B, 801-811 (2013).
In the present study, classical MD simulations using reverse non- equilibrium molecular dynamics with the AMEBO interatomic potential are used to investigate the sensitivity of thermal conductivity in SWCNTs to side-wall defect concentration and heat-treatment. Two types of defects are investigated. First, the thermal conductivity of (6,6) SWCNTs is obtained as a function of concentration of chemisorbed hydrogen adatoms. Secondly, the thermal conductivity is obtained as a function of point- vacancy concentrations. The results of the studies show that 2 atom % of hydrogenation and 1.5 - 2 % vacancy concentrations have very similar detrimental effects on the thermal conductivity of SWCNT. Vacancy repair is evident with heat treatment, and heat-treatments at 3000 C for up to 22 ns are found to transform point vacancies into various types of non- hexagonal side-wall defects; this vacancy repair is accompanied by a ca. 10% increase in thermal conductivity. Thermal conductivity measurements in both heat-treated and non-heat treated chemical vapor deposition grown MWCNTs are also reviewed. The results suggest that CNT thermal conductivity can be drastically increased if measures are taken to remove common defects from the SWCNT side-walls.
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