Influence of Different Type of Irradiation to Carbon Nanotubes
585
Radiation irradiation with a dose of D ≈ 10
17 r.p./cm
2 leads to a decrease in
electrical conductivity and an increase in the Seebeck coefficient (α): when electrons
are irradiated with E = 21 MeV, α increases from 26 to 36 μV/K, and from E =
2 MeV—up to 45 μV/K, when γ-irradiated with E = 1.2 MeV the highest increase
of Seebeck coefficient up to 55 μV/K is observed. These results indicate the different
nature of the defects that are formed during the growth of nanotubes and under the
action of radiation. The prospect is to create defects in the CNTs that reduce the
potential barriers between the contacting nanotubes through which charge carriers
are tuned, and the phonons on them are scattered, which reduces unwanted heat
dissipation and is important for increasing the thermoelectric figure of merit of the
carbon nanotube array.
The density of the transition to the conductive state of the CNT array is determined by the concentration of topological defects (Stone–Wales, paired vacancies,
adsorbed carbon atoms), which increase the degree of curvature of the shape relatively
straightforward for defect-free nanotubes.
Each of the defects of different genesis: growth and radiation origin, separately
leads to distortion of the nanotube shape, which indicates the creation of a topological
disorder, which is accompanied by a decrease in electrical conductivity and the
increase of thermo-EMF. But with their combined action, the degree of curvature of
the nanotube shape does not increase, and on the contrary, it substantially decreases,
which indicates the interaction of defects and the effective “healing” of both radiation
and growth defects by the migration of broken carbon atoms along with graphene
layers and their recombination.
References
1. Yao Z, Postma HWCh, Balents L, Dekker C (1999) Carbon nanotube intramolecular junctions.
Nature 402:273–276
2. Seamus A, Curran SA, Talla J, Dias S, Zhang D (2009) Electrical transport measurements of
highly conductive carbon nanotube/poly(bisphenol A carbonate) composite. Carroll D J Appl
Phys 105:073711–073718
3. Ahmad K, Pan W, Shi SL (2006) Electrical conductivity and electrical properties of multiwall
carbon nanotubes and alumina composities. Appl Phys Lett 89:133122–133128
4. Sandler JKW, Kirk JE, Kinloch IA, Shaffer MSP, Windle AH (2003) Ultra-low electrical
percolation threshold in carbon-nanotube-epoxy composites. Polymer 44:5893–5899
5. Bryning MB, Islam MF, Kikkawa JM, Yodh AG (2005) Very low conductivity threshold in
bulk isotropic single-walled carbon nanotube-epoxy composites. Adv Mater 17: 1186–1191
6. Kymakis E, Alexandou I, Amaratunga GA (2002) Single-walled carbon nanotube-polymer
composites: electrical, optical and structural investigation. Synthetic Metals 127:59–62
7. Bryning MB, Milkie DE, Islam MF, Kikkawa JM, Yodh AG (2005) Thermal conductivity
and interfacial resistance in single-wall carbon nanotube epoxy composites. Appl Phys Lett
87:161909–161909-3
8. DeHeer WA (1995) Aligned carbon nanotu be films: production and optical and electronic
properties. DeHeer WA, Bacsa WS, Chatelain A, Gerfin T, Humphreybaker R, Forro L, Ugarte
D. Science 268:845–847
9. Fischer JE, Dai H, Thess A, Lee R, Hanjani NM, Dehaas DL, Smalley RE (1997) Metallic
resistivity in crystalline ropes of single-wall carbon nanotubes. Phys Rev B 55:R4921–R4924
585
Radiation irradiation with a dose of D ≈ 10
17 r.p./cm
2 leads to a decrease in
electrical conductivity and an increase in the Seebeck coefficient (α): when electrons
are irradiated with E = 21 MeV, α increases from 26 to 36 μV/K, and from E =
2 MeV—up to 45 μV/K, when γ-irradiated with E = 1.2 MeV the highest increase
of Seebeck coefficient up to 55 μV/K is observed. These results indicate the different
nature of the defects that are formed during the growth of nanotubes and under the
action of radiation. The prospect is to create defects in the CNTs that reduce the
potential barriers between the contacting nanotubes through which charge carriers
are tuned, and the phonons on them are scattered, which reduces unwanted heat
dissipation and is important for increasing the thermoelectric figure of merit of the
carbon nanotube array.
The density of the transition to the conductive state of the CNT array is determined by the concentration of topological defects (Stone–Wales, paired vacancies,
adsorbed carbon atoms), which increase the degree of curvature of the shape relatively
straightforward for defect-free nanotubes.
Each of the defects of different genesis: growth and radiation origin, separately
leads to distortion of the nanotube shape, which indicates the creation of a topological
disorder, which is accompanied by a decrease in electrical conductivity and the
increase of thermo-EMF. But with their combined action, the degree of curvature of
the nanotube shape does not increase, and on the contrary, it substantially decreases,
which indicates the interaction of defects and the effective “healing” of both radiation
and growth defects by the migration of broken carbon atoms along with graphene
layers and their recombination.
References
1. Yao Z, Postma HWCh, Balents L, Dekker C (1999) Carbon nanotube intramolecular junctions.
Nature 402:273–276
2. Seamus A, Curran SA, Talla J, Dias S, Zhang D (2009) Electrical transport measurements of
highly conductive carbon nanotube/poly(bisphenol A carbonate) composite. Carroll D J Appl
Phys 105:073711–073718
3. Ahmad K, Pan W, Shi SL (2006) Electrical conductivity and electrical properties of multiwall
carbon nanotubes and alumina composities. Appl Phys Lett 89:133122–133128
4. Sandler JKW, Kirk JE, Kinloch IA, Shaffer MSP, Windle AH (2003) Ultra-low electrical
percolation threshold in carbon-nanotube-epoxy composites. Polymer 44:5893–5899
5. Bryning MB, Islam MF, Kikkawa JM, Yodh AG (2005) Very low conductivity threshold in
bulk isotropic single-walled carbon nanotube-epoxy composites. Adv Mater 17: 1186–1191
6. Kymakis E, Alexandou I, Amaratunga GA (2002) Single-walled carbon nanotube-polymer
composites: electrical, optical and structural investigation. Synthetic Metals 127:59–62
7. Bryning MB, Milkie DE, Islam MF, Kikkawa JM, Yodh AG (2005) Thermal conductivity
and interfacial resistance in single-wall carbon nanotube epoxy composites. Appl Phys Lett
87:161909–161909-3
8. DeHeer WA (1995) Aligned carbon nanotu be films: production and optical and electronic
properties. DeHeer WA, Bacsa WS, Chatelain A, Gerfin T, Humphreybaker R, Forro L, Ugarte
D. Science 268:845–847
9. Fischer JE, Dai H, Thess A, Lee R, Hanjani NM, Dehaas DL, Smalley RE (1997) Metallic
resistivity in crystalline ropes of single-wall carbon nanotubes. Phys Rev B 55:R4921–R4924