Note : These pages are in no way an exhaustive review of all the tremendous amount of work that as been published in the field. I welcome any remark or any proposal for links and bibliography.
Quick jumps :
Basically, there are 2 types of methods to get a carbon nanostructure. For those two methods, the morphologies obtained differ quite a lot.
Slow methods (The CVD techniques):
It is a chemical deposition (the deposition can be led for severaldays) through pyrolysis (the sample and the surrounding are heated, typicallyaround 700 C) of a hydrocarbide (acetylene, ethylene, benzene...) overa template substrate (for example, iron nano-particules embedded in silica).
See for instance : Z. W. Pan et al. - Very long carbon nanotube-nature, vol. 394, 13 aug. 1998
Krätschmer arc methods:
It is the most widely used method to synthesize carbon nanostructure because it is rather simple to undertake in laboratory. The principle is to submit 2 graphite electrodes to a high currentdischarge (typically 20V, 50A) inside an enclosure filled with inert gas(helium, argon...) at low pressure (between 50 and 700 mbar). Metallicparticles can be added in the initial electrodes to catalyse single wallnanotubes.
See W. Krätschmer, L.D. Lamb, K. Fostiropoulos, D.R. Huffman
, Solid C60 : a new form of carbon - Nature 347, 354-358 (1990)
and C. Journet et al.- Large scale production of single-walled carbon nanotubes by the electric-arc technique - Nature 388 21 aug. 1997
The laser ablation methods:
It is rather similar to the arc method and was in fact the first one tobe
developed. Studies (mainly in Rice university) have proved that it canlead
to very similar structures to those obtained by the arc method : fullerenes,
nanotube multi or mono-layered, onions...
The main differences are :
See A. Thess et al. - Crystalline ropes of metallic carbon nanotubes- science, vol. 273, 26 july 1996
|Carbon's methods in brief||Slow methods (several days)||Fast methods (several minutes)|
|Techniques||CVD: (chemical vapour deposition)
Pyrolysis (700 °C)of a hydrocarbon (acetylene, ethylene, benzene...) over a template substrate (iron nano-particles embedded in silica…)
Electric arc discharge between graphite rods in inert atmosphere atlow pressure
(Pulsed) laser ablation :
|Results||Large arrays of tubes
long (up to 2 mm)
but thick (diameter > 20 nm)
No other morphology is obtained
|All types of nanostructures
(including Ropes of SWNT)
Tubes are shorter (100 µm)
but thin (> 1 nm)
|Usually proposed Nucleation processes||Growth on surface through atoms of the gas phase captured on large catalyst particles.||Arc discharge :
tubes -> growth on the electrodes tip
spherical structures -> growth in plasma
For BN, many methods were inspired from carbon. But, to make an equivalent of carbon production (thin tubes over the micron scale, ropes, quantity higher that what is needed for electron microscopy observations...) remainded a challenge untill very recent days.
Non ablative laser heating method
Low power continuous CO2 laser on h-BN
target in static N2 atmosphere
Thin BN tubes hundred micron long and nanopolyhedral BN/B particles. Macroscopic crown-like growth around impact.
T. laude, Y matsui, A. Marraud, B. jouffrey, Appl Phys Let 76, 22, p. 3239, (2000)
Arc discharge methods
Arc discharge on a hollow tungsten electrode filled with h-BN
Thin tubes < 200 nm + W particles
Chopra, N. G. et al. Boron nitride nanotubes. Science 269, 966-967(1995)
Arc discharge on a HfB2 electrode in N2
Thin tubes < 700 nm + Hf particles
A. Loiseau, F. Willaime, N. Demoncy, G. Hug, H. Pascard - Boron nitride nanotubes with reduced numbers of layers synthesized by arc-discharge -Phys. Rev. Lett. 76, 4737 (1996).
Arc discharge on a ZrB2 electrode in N2
Thin tubes < 100 nm + Zr particles
Y. saito, M. Maida,J. of Phys. Chem A 103, 10, 1291 (1999)
Arc discharge on B electrode in N2
BN bi-layered tubes several micron long and "nanococoons". Macroscopic quantities.
J. Cumings, A. Zettl, Chem. Phys. Let. 316, 211 (2000)
Laser ablation method
Excimer laser ablation of h-BN (in He)Yu
Thin tubes < 100 nm (+ Ni & Co)
D. P. Yu et al., Apl. Phys. Lett. 72, 16, 1966 (1998)
and G. W. Zhou, Z Zhang, Z. G. Bai, D. P. Yu, Sol. St. Com. 109,555 (1999)
H. P. compression (5-15 Gpa) of c-BN micro-crystals in a diamond anvil
cell induced by laser heating
A few short tubes < 30 nm.
D. Golberg et al, Appl. Phys. Lett. 69 (14), 2045-2047 (1996)
Oven Heating (1200*C) of B and Li in a BN crucible in N2 atmosphere
A few short tubes < 30 nm + Li particles
M. Terauchi, M. Tanaka, H. Matsuda, M. Takeda & K. Kimura, Helical nanotubes of hexagonal boron nitride. Journ. of Elec. Micros. 46 (1), 75-78 (1997)
Oven heating (1000*C) of B previously ball milled in ammonia
Large filaments < 5 µm
Y. Chen, J.F. Gerald, J.S. Williams, S. Bulcock, Chem. Phys. Lett.299, 260 (1999)
Oven heating (1100 *C) of B2H6 + NH3 + ZrB2
Large filaments < 10 µm + ZrB2 particles
P. Gleize, M.C. Schouler, P. Gadelle, M. Caillet, J. of Mat. Science 29, 1575 (1994)
"Substitution" of C to BN in oxydizing atmosphere (Mechanism proposed by the authors of the
Transformation of micrometer carbon multiwalled nanotube into BN nanotube.Or doping carbon SWNT ropes with some percentage of B/N
W. Han, Y. Bando, K. Kurashima, T. Sato, Appl. Phys. Let.73,21, 3085 (1998)
and D. Golberg, Y. Bando, W. Han, K. Kurashima, T. Sato, Chem. Phys.let. 308, 337 (1999)