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

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Carbon nanotube (CNT) is <strong>the</strong> last carbon structure to be dealt with in <strong>the</strong> following section in this <strong>the</strong>sis. 2.2. Carbon Nanotubes 2.2.1. Historical Background When electron microscopes became popular in <strong>the</strong> research fields, Radushkevich et al. discovered <strong>the</strong> first tubular form <strong>of</strong> carbon by using an electron microscope in 1952 (Radushkevich, et al. 1952). However, not much interest was shown to <strong>the</strong> early reports <strong>of</strong> carbon nanotubes by <strong>the</strong> scientists. In 1991, while <strong>the</strong> Japanese scientist Sumio Ijima was doing some experiments to observe fullerene, he observed ano<strong>the</strong>r form <strong>of</strong> carbon (graphitic tubules). After <strong>the</strong> discovery, that structure <strong>of</strong> carbon has been given a name, „carbon nanotube‟(CNT) (Dupuis 2005). The first observed and described CNT was multi-walled carbon nanotube (MWNT) which was grown by using arc-discharge method. A few years later, <strong>the</strong> second type <strong>of</strong> CNT called single-walled carbon nanotube (SWNT) was discovered by using two different growth methods (chemical vapor deposition (CVD) and laser ablation method) (Dupuis 2005, Iijima and Ichihashi 1993). 2.2.2. Types <strong>of</strong> Carbon Nanotubes Depending on <strong>the</strong> number <strong>of</strong> a CNT‟s graphene cylinders, <strong>the</strong>re are two types <strong>of</strong> CNT. When a CNT contains one graphene cylinder, it is called single-walled carbon nanotube. On <strong>the</strong> o<strong>the</strong>r hand, <strong>the</strong> second type <strong>of</strong> CNT, multi-walled carbon nanotube, has more than one concentric cylinder. 2.2.2.1. Single-Walled Carbon Nanotube A single-walled carbon nanotube (SWNT) can be considered to be formed by <strong>the</strong> rolling <strong>of</strong> a single graphene cylinder with <strong>the</strong> diameter ranging from 0.4 to 5 nm, and also it can be classified as ei<strong>the</strong>r metallic or semiconducting. SWNTs are mostly 5
preferred nanotube type because <strong>of</strong> <strong>the</strong>ir perfect electrical, mechanical and structural properties as well as <strong>the</strong>ir having less defects with compared to MWNT (Dai 2002). The shape <strong>of</strong> a SWNT is depicted in Figure 2.4. Figure 2.4. An illustration <strong>of</strong> a SWNT (Source: Dresselhaus, et al. 2003) 2.2.2.2. Multi-Walled Carbon Nanotube A multi-walled carbon nanotube (MWNT) consists <strong>of</strong> two or more concentric cylindrical shells with an interlayer spacing <strong>of</strong> 0.34 nm (Popov 2004) <strong>of</strong> graphene sheets coaxially arranged around a central hollow core. Each individual tube can have different chirality (Thostenson, et al. 2001). The diameter <strong>of</strong> this type <strong>of</strong> CNT ranges from 2 to 100 nm (Merkoçi 2006), depending on <strong>the</strong> method <strong>of</strong> syn<strong>the</strong>sis, and <strong>the</strong>ir lengths up to µm or even cm (Dai 2002). The shape <strong>of</strong> a MWNT is shown in Figure 2.5. Although <strong>the</strong> atoms <strong>of</strong> SWNT are held with covalent bonding, <strong>the</strong> concentric tubes are held toge<strong>the</strong>r by Van der Waals bonding in MWNT (Thostenson, et al. 2001). MWNT acts primarily like metallic conductors (some can be semiconducting with very small band gaps). MWNT is stronger than SWNT, but <strong>the</strong>y have more defects than SWNT (Dai 2002). MWNT contains imperfections that can limit <strong>the</strong>ir properties because <strong>of</strong> having multiple walls with concentric cylinders around <strong>the</strong> inner tube (Schwartz 2006). 6
Page 1 and 2: THE EFFECTS OF OXIDIZERS ON THE DIA
Page 3 and 4: ACKNOWLEDGEMENTS During my master <
Page 5 and 6: ÖZET KİMYASAL BUHAR BİRİKTİRME
Page 7 and 8: TABLE OF CONTENTS LIST OF FIGURES .
Page 9 and 10: LIST OF FIGURES Figure Page Figure
Page 11 and 12: Figure 5.12. The growths with CO2 (
Page 13 and 14: Figure 5.36. Raman spectra
Page 15 and 16: Table 5.12. The amounts of<
Page 17 and 18: first two methods, arc discharge an
Page 19: Graphite is the mo
Page 23 and 24: Figure 2.7. An illustration <strong
Page 25 and 26: Table 2.1. Advantages and disadvant
Page 27 and 28: 2.3.2. The Laser-Ablation Method Th
Page 29 and 30: hydrocarbons (Cui, et al. 2003) wit
Page 31 and 32: 2.3.3.1.2. Thin Film Support Layer
Page 33 and 34: 2.4. Growth Mechanism of</s
Page 35 and 36: (Amama, et al. 2009, Hata, et al. 2
Page 37 and 38: that the small amo
Page 39 and 40: Figure 4.1. The Magnetron Sputterin
Page 41 and 42: the tube as <stron
Page 43 and 44: Table 4.1 (cont.) FeAlO15CNT840 750
Page 45 and 46: their diameter rou
Page 47 and 48: The principle of R
Page 49 and 50: Figure 4.6. Schematic picture showi
Page 51 and 52: 5.1.1. AFM Results There exists a p
Page 53 and 54: a ) Figure 5.2. AFM micrographs <st
Page 55 and 56: c Figure 5.3. (cont.) Element Wt %
Page 57 and 58: Table 5.2. (cont.) FeAlO12CNT771 76
Page 59 and 60: a b c e Figure 5.4. The growths wit
Page 61 and 62: Figure 5.5. (cont.) Count 35 30 25
Page 63 and 64: Due to the lack <s
Page 65 and 66: a c e Figure 5.8. The growths with
Page 67 and 68: Figure 5.9. (cont.) Count 45 40 35
Page 69 and 70: Table 5.6 shows that the</s
Page 71 and 72:
a c e Figure 5.12. The growths with
Page 73 and 74:
Figure 5.13. (cont.) Count 45 40 35
Page 75 and 76:
In this part, for the</stro
Page 77 and 78:
For FeAlO15 substrate, two differen
Page 79 and 80:
For FeAlO16 substrate, two differen
Page 81 and 82:
e f Figure 5.20. (cont.) Due to <st
Page 83 and 84:
5.2.1.3. CNT Formation at Different
Page 85 and 86:
Count 30 25 20 15 10 5 0 a 5 10 15
Page 87 and 88:
Count 35 30 25 20 15 10 5 0 a CNT 8
Page 89 and 90:
Count 40 35 30 25 20 15 10 5 0 a CN
Page 91 and 92:
Count 45 40 35 30 25 20 15 10 5 0 a
Page 93 and 94:
Count 30 25 20 15 10 5 0 a 5 10 15
Page 95 and 96:
for SWNTs, there i
Page 97 and 98:
Table 5.17. (cont.) FeAlO15 CNT773
Page 99 and 100:
Intensity (a.u.) 2700 1800 900 CNT8
Page 101 and 102:
Intensity (a.u.) 2100 1400 700 CNT9
Page 103 and 104:
whole face. The formed catalyst par
Page 105 and 106:
Diameter Diameter 10 8 6 4 2 0 5 5
Page 107 and 108:
5.4. Statistical Analysis Results A
Page 109 and 110:
Kurtosis value is a descriptor <str
Page 111 and 112:
Very thin Fe films were grown on Si
Page 113 and 114:
REFERENCES Amama, P.B., C.L. Pint,
Page 115 and 116:
Hasegawa, K. and S. Noda. 2011a. Mi
Page 117 and 118:
Makita, Y., S. Suzuki, H. Kataura,
Page 119 and 120:
Vesselényi, I., K. Niesz, A. Siska
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