the effects of oxidizers on the diameters of the carbon nanotubes ...

Figure 2.5. An illustration <strong>of</strong> a MWNT
(Source: Dresselhaus, et al. 2003)
2.2.3. Classification <strong>of</strong> Carbon Nanotubes
When a graphene sheet is rolled into tubular form, <strong>the</strong> structure can be in three
different configurations such as; armchair, zigzag, and finally chiral carbon nanotube.
The formations <strong>of</strong> three different CNTs are shown in Figure 2.6.
Figure 2.6. Classification <strong>of</strong> CNTs a) Zigzag (n, 0) b) Armchair (n=m) c) Chiral (n≠m)
CNTs (Source: Dresselhaus, et al. 1998)
As shown in Figure 2.7, <strong>the</strong> orientation <strong>of</strong> chiral vector is
where a1 and a2 are <strong>the</strong> unit base cell vectors <strong>of</strong> graphene honeycomb lattice and n and
m are integers. The diameter <strong>of</strong> CNT is determined by <strong>the</strong> (n,m) or (m,n) indices called
„chirality‟ (Dai 2002). „Chiral angle (θ)‟ is known as <strong>the</strong> angle between <strong>the</strong> chiral vector
(Ch) and <strong>the</strong> unit vector (a1), which determines <strong>the</strong> direction <strong>of</strong> <strong>the</strong> chiral vector and
gives information about orientations <strong>of</strong> CNTs.
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