Temperature dependence of the tensile properties of single-walled carbon nanotubes: $\mathrm{O}\left(N\right)$ tight-binding molecular-dynamics simulations

This paper examines the effect of temperature on the structural stability and mechanical properties of 20-layered (10,10) single-walled carbon nanotubes (SWCNTs) under tensile loading using an $\mathrm{O}\left(N\right)$ tight-binding molecular-dynamics simulation method. We observed that (10,10) tube can sustain its structural stability for the strain values of 0.23 in elongation and 0.06 in compression at $300\mathrm{K}$. Bond-breaking strain value decreases with increasing temperature under stretching but not under compression. The elastic limit, Young’s modulus, tensile strength, and Poisson ratio are calculated as 0.10, $0.395\mathrm{TPa}$, $83.23\mathrm{GPa}$, and 0.285, respectively, at $300\mathrm{K}$. In the temperature range from $300\text{to}900\mathrm{K}$, Young’s modulus and the tensile strengths decrease with increasing temperature while the Poisson ratio increases. At higher temperatures, Young’s modulus starts to increase while the Poisson ratio and tensile strength decrease. In the temperature range from $1200\text{to}1800\mathrm{K}$, the SWCNT is already deformed and softened. Applying strain on these deformed and softened SWCNTs does not follow the same pattern as in the temperature range of $300\text{to}900\mathrm{K}$.

Figure 1

(Color online) Total energy per atom curves as a function of strain at different temperatures (negative strain values correspond to compression).

Figure 2

(Color online) (a) (10,10) SWCNT is stable for the strains of 0.23 and $-0.06$ at $300\mathrm{K}$. (b)(Color online) Bond breakings are observed between the carbon atoms for the strains of 0.24 and $-0.07$ at $300\mathrm{K}$. System is not in equilibrium.

Figure 3

(Color online) Bond-breaking strain variations as a function of temperature for (a) tension, and (b) compression.

Figure 4

(Color online) (a) (10,10) SWCNT is stable for the strains of 0.14 and $-0.06$ at $900\mathrm{K}$. (b) Bond breakings are observed between the carbon atoms for the strains of 0.15 and $-0.07$ at $900\mathrm{K}$. System is not in equilibrium.

Figure 5

(Color online) (a) (10,10) SWCNT is stable for the strains of 0.08 and $-0.03$ at $1800\mathrm{K}$. (b) Bond breakings are observed between the carbon atoms for the strains of 0.09 and $-0.04$ at $1800\mathrm{K}$. System is not in equilibrium.

Figure 6

(Color online) The stress-strain curves of (10,10) SWCNT at different temperatures.