Photonic crystals in biology

Poster Session, Tuesday, June 15
Theme A1 - B702
The Effect of Vacancies on the Mechanical Properties of (10,10) Single Walled Carbon Nanotubes
Gülay Dereli*, Banu Süngü* and Önder Eyeciolu
Department of Physics, Yildiz Technical University, stanbul 34210, Turkey
Abstract— In this work, we aimed to show the effect of vacancies on the structural stability, tensile strength and Young modulus of (10,10)
Single Walled Carbon Nanotubes (SWCNTs). We used O(N) tight-binding molecular dynamics (TBMD) simulation method. We studied at 300K
to except the effect of temperature and to study with the brittle SWCNTs. We have concluded the results with respect to the defect free and single
vacancy defect results of (10,10) SWCNTs.
Soon after their discovery, carbon nanotubes become
most promising materials due to their extremely small
dimensions, mechanical strength, as well as, elasticity and
adjustible electronic properties. These remarkable
characteristics lead to many important applications in
nanotechnology. In our previous works, we have shown that
temperature has significant effects on the thermal stability and
mechanical properties of nanotubes [1-3]. On the other hand,
the recent high-resolution transmission electron microscopy
(HR-TEM) studies and computational simulation results point
out that the structural defects play a crucial role on the
electronic, optical and mechanical properties of carbon
nanotubes [4-13]. These studies show variety of results
according to the methods and the defects. Several kinds of
defects may occur on carbon nanotubes. Here we examined
the vacancy defects on the atomic structure. We used a parallel
O(N) TBMD code designed by Dereli et al [14-16]. We
studied at 300K to except the effect of temperature and to
study with the brittle SWCNTs.
During our simulations, we first optimized a pristine
(10,10) SWCNT using the “thermal equilibrium” method as
described in [1]. Then multiple amount of vacancies are
generated on the tube structure and the tensile loading is
applied to the defected tube. Using this procedure, we
investigated the structural stability and the bond breaking
strain values of the (10,10) SWCNT. The stress-strain curve of
the nanotube is obtained and the mechanical parameters such
as the tensile strength, elastic limit, Young modulus are
calculated. In our work of [17], we investigated the effect of
single vacancy defect on the tensile properties of (10,10)
SWCNTs and we compared the results with the pristine tube
[2]. In the study, we have shown that a single vacancy defect
decreased the bond breaking strain from 23% to 16%. The
elastic limit maintained its value as 10%. A single vacancy
defect did not represent a significant effect on the Young’s
modulus of SWCNTs, which is calculated as a decrease of
1.5%. However it is shown that a single vacancy defect is
observed to reduce the tensile strength from 83.23 GPa to
64.14 GPa which corresponds to 23% decrease.
Here we reach one step ahead from these studies to
clarify the decreasing ratios of tensile strength and mechanical
parameters with respect to the certain amount of vacancies.
Figure 1(a), shows the difference between the total energy
values of pristine (10,10) tube and the (10,10) tube with 4 -
vacancies. Last 2000MD Step in Figure 1(b), (c) and (d) show
the total energy results of (10,10) tube under 5%, 10% and
15% strain, respectively. Figure 1 and the corresponding
simulation pictures of Figure 2, show that the simulated
carbon nanotube with 4 - vacancies can not carry the strain
when it is stretched to 10 -15% of its original length. This
work will set lights to the applications of carbon nanotubes
with vacancy defects which is very common during their
formation. Careful study on the bond breaking values of these
SWCNTs during stretching will be done. Effect of 4-vacancies
on the structural stability, tensile strength and Young modulus
will be reported.
Total energy (eV/atom)
Total energy (eV/atom)
-7,8
-8,0
-8,2
-8,20
-8,24
-8,28
-8,32
(a)
0 2000 4000 6000
MD Step
10%
-8,15
-8,20
-8,25
-8,30
(b)
-8,35
0 2000 4000 6000 8000
MD Step
-7,6
15%
-7,8
(c)
(d)
-8,4
-8,4
0 2000 4000 6000 8000 0 2000 4000 6000 8000
MD Step
MD Step
Figure:1 Total energy per atom results of (10,10) SWCNT (a) with 4 –vacancies;
(b) under 5% strain; (c) under 10% strain; (d) under 15% strain.
-8,0
-8,2
Figure:2 Simulation pictures of (10,10) tube (a) with 4 –vacancies;
(b) under 5% strain; (c) under 10% strain; (d) under 15% strain.
The research reported here is supported through the Yildiz
Technical University Research Fund Project No: 24-01-01-04.
The simulations are performed at the Carbon Nanotubes
Simulation Laboratory at the Department of Physics, Yildiz
Technical University, Istanbul, Turkey.
(http://www.yildiz/edu/tr/~gdereli/lab_homepage/index.html)
*Corresponding author: gdereli@yildiz.edu.tr
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6th Nanoscience and Nanotechnology Conference, zmir, 2010 399