U.S. patent application number 10/543509 was filed with the patent office on 2006-05-04 for process for producing monolayer carbon nanotube with uniform diameter.
This patent application is currently assigned to BUSSAN NANOTECH RESEARCH INSTITUTE INC.. Invention is credited to Shigeo Maruyama, Yuhei Miyauchi.
Application Number | 20060093545 10/543509 |
Document ID | / |
Family ID | 33487025 |
Filed Date | 2006-05-04 |
United States Patent
Application |
20060093545 |
Kind Code |
A1 |
Maruyama; Shigeo ; et
al. |
May 4, 2006 |
Process for producing monolayer carbon nanotube with uniform
diameter
Abstract
Provided is a process for producing a single-walled carbon
nanotube on a substrate on which a lot of fine particles comprising
at least one kind of a catalyst metal are formed in a reaction
apparatus maintained in vacuum, wherein at least one kind of
fullerene C.sub.2n's (n is an integer of n.gtoreq.18) is sublimated
at a prescribed temperature or higher to produce a fullerene gas in
which a partial pressure is controlled; the fullerene gas is
transported on the substrate heated at a sublimation temperature of
the fullerene or higher; and the fullerene gas is brought into
contact with the catalyst metal fine particles described above to
produce a single-walled carbon nanotube. The vacuum degree is
preferably 0.5 Torr or less, and the sublimation temperature is
preferably 700.degree. C. or higher. The substrate has a thin film
of a porous substance or an inorganic oxide, and transition metal
catalyst fine particles having a particle diameter of 0.5 to 10 nm
are formed on the above thin film.
Inventors: |
Maruyama; Shigeo;
(Setagaya-ku, JP) ; Miyauchi; Yuhei;
(Sagamihara-shi, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
BUSSAN NANOTECH RESEARCH INSTITUTE
INC.
|
Family ID: |
33487025 |
Appl. No.: |
10/543509 |
Filed: |
February 9, 2004 |
PCT Filed: |
February 9, 2004 |
PCT NO: |
PCT/JP04/01348 |
371 Date: |
July 27, 2005 |
Current U.S.
Class: |
423/447.3 |
Current CPC
Class: |
B82Y 40/00 20130101;
C01B 32/162 20170801; C01B 2202/02 20130101; C01B 2202/36 20130101;
B82Y 30/00 20130101 |
Class at
Publication: |
423/447.3 |
International
Class: |
D01F 9/12 20060101
D01F009/12 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 7, 2003 |
JP |
2003-031508 |
Claims
1. A process for producing a single-walled carbon nanotube on a
substrate on which a lot of fine particles comprising at least one
kind of a catalyst metal are formed in a reaction apparatus
maintained in vacuum, wherein at least one kind of fullerene
C.sub.2n's (n is an integer of n.gtoreq.18) is sublimated at a
prescribed temperature or higher to produce a fullerene gas in
which a partial pressure is controlled; the fullerene gas is
transported on the above substrate heated at a sublimation
temperature of the fullerene or higher; and the fullerene gas is
brought into contact with the catalyst metal fine particles
described above to produce a single-walled carbon nanotube.
2. The process for producing a single-walled carbon nanotube as
described in claim 1, wherein a pressure in the reaction apparatus
is 0.5 Torr or less.
3. The process for producing a single-walled carbon nanotube as
described in claim 2, wherein the pressure in the reaction
apparatus is 0.05 Torr or less.
4. The process for producing a single-walled carbon nanotube as
described in claim 1, wherein the sublimation temperature is
700.degree. C. or lower.
5. The process for producing a single-walled carbon nanotube as
described in claim 1, wherein the fullerene involves chemically
modified fullerene.
6. The process for producing a single-walled carbon nanotube as
described in claim 1, wherein the catalyst metal is a transition
metal belonging to the fifth A group, the sixth A group and the
eighth group in the periodic table of elements.
7. The process for producing a single-walled carbon nanotube as
described in claim 6, wherein the catalyst metal is any simple
substance of Fe, Co, Mo, Ni, Rh, Pd and Pt or a mixture of two
kinds thereof or more.
8. The process for producing a single-walled carbon nanotube as
described in claim 1, wherein the substrate has a thin film
comprising at least one of a porous substance and an inorganic
oxide, and the fine particles described above are formed on the
thin film.
9. The process for producing a single-walled carbon nanotube as
described in claim 8, wherein the porous substance is an inorganic
porous substance.
10. The process for producing a single-walled carbon nanotube as
described in claim 9, wherein the inorganic porous substance is
zeolite.
11. The process for producing a single-walled carbon nanotube as
described in claim 10, wherein the zeolite is a Y type.
12. The process for producing a single-walled carbon nanotube as
described in claim 8, wherein the thin film of the inorganic oxide
is a silicon oxide film.
13. The process for producing a single-walled carbon nanotube as
described in claim 1, wherein the fine particles have a particle
diameter of 0.5 to 10 nm.
Description
TECHNICAL FIELD
[0001] The present invention relates to a production process for a
single-walled carbon nanotube (hereinafter referred to as SWNT) by
sublimating fullerene, specifically to a production process for
SWNT in which a diameter of SWNT is controlled by fullerene used or
chemically modified fullerene used.
BACKGROUND ART
[0002] A carbon nanotube (hereinafter referred to as CNT) is a
carbon cluster comprising a cylindrically wound graphene sheet and
having a cross-sectional diameter of 100 nm or less. It is reported
in many cases that particularly a single-walled carbon nanotube
comprising one layer of a graphene sheet is useful as a nano
structural material because of specific electrical and chemical
characteristics thereof. In particular, it has become clear from
theoretical calculation that SWNT shows various properties
extending from semiconductor to metal according to chirality
thereof, and therefore if the chirality can be controlled in
production or at a separating and refining step, SWNT is expected
to have very high industrial usefulness.
[0003] A lot of the above trials are reported in terms of science,
but examples which are possible to be industrially put into
practice have not yet been reported. On the other hand, SWNT has a
structure in which a graphene sheet is wound into a cylinder, and
therefore if a diameter of SWNT can strictly be controlled,
chirality can approximately be controlled without directly
controlling the chirality. On the other hand, a variety of
chirality which can substantially be assumed is narrowed by
narrowing a range of a diameter of SWNT.
[0004] Known as a production process for SWNT are an arc discharge
process, a laser ablation process, a high frequency plasma process
and a thermal decomposition process (a chemical vapor deposition
(CVD) process and a catalytic chemical vapor deposition (CCVD)
process). In respect to controlling a diameter of SWNT, reported
are scientific trials such as controlling a diameter distribution
by controlling production conditions including changing
temperatures of a catalyst and a furnace and changing a kind and a
pressure of an inert gas and obtaining only SWNT falling in the
vicinity of a specific diameter by subjecting a mixture of SWNT to
heat treatment. However, the controlled SWNT has not yet been
surely separated.
[0005] A process in which SWNT is produced by reacting a mixture of
linear single-walled or multi-walled carbon nanotubes in a carbon
material plasma containing --C.ident.C-- or --C.dbd.C-- is
disclosed in Japanese Patent Application Laid-Open No. 203819/2000.
It is described that a length of CNT can be controlled by the above
process.
[0006] It is a subject in Japanese Patent Application Laid-Open No.
058805/2001 to produce CNT in a high yield in a simple manner by a
process in which a mixture of the same or different kind of
fullerene molecules is mixed with a transition metal element or an
alloy thereof to produce CNT at 500.degree. C. or higher under a
reduced pressure in an inert gas atmosphere.
[0007] In Japanese Patent Application Laid-Open No. 089117/2001, a
compound having a five-membered ring of carbon such as fullerene is
added to a laser-irradiation target in producing CNT by a laser
ablation process, and a catalyst is further mixed with the target,
whereby SWNT is produced at a low temperature. However, it is not
described to control a diameter of SWNT.
[0008] Disclosed in Japanese Patent Application Laid-Open No.
029717/2002 is a production process for a carbon material in which
at least one of fullerene and CNT is mixed with amorphous carbon
and the mixture is subjected to heat treatment to turn the
amorphous carbon into fullerene or CNT. It is described that CNT
having a certain length is obtained, but the diameter thereof is
not described.
[0009] Further, Zhang and Iijima showed that when a mixture of
C.sub.60 powder and 5 at % of Co and Ni is used as a
laser-irradiation target in a laser oven process, SWNT could be
produced, though in a trace amount and covered with amorphous
carbon, even at an electric furnace temperature of 400.degree. C.,
and that when used graphite, SWNT could not be produced without
elevating a temperature of an electric furnace (oven) to about
850.degree. C. (Y. Zhang and S. Iijima, Appl. Phys. Lett., 75
(1999), 3087). In this case, it is considered that a fullerene
structure is destroyed by irradiating with laser and that what is
useful for synthesis of SWNT is fragments which are not completely
broken to small pieces by the laser. It is considered that any
carbon material can be a raw material for SWNT by vaporizing with
laser, and as a result, the process can not regard as a process for
synthesizing SWNT from fullerene. In this connection, the oven
temperature is set to 400.degree. C. in order to prevent fullerene
from being sublimated. An amount of SWNT is too small, and
therefore it is difficult to judge the level of the diameter from
Raman spectra, but it is considered that the diameter is almost
unchanged from that obtained by using a graphite material.
[0010] Further, Champbell et al. tried to produce a nanotube by a
CCVD process, but what could be produced was a multi-walled
nanotube (L. P. Biro, R. Ehlich, R. Tellgmann, A. Gromov, K.
Krawez, M. Tschaplyguine, M. M. Pohl, E. Zsoldos, Z. Vertesy, Z. E.
Horvath and E. E. B. Champbell: Chem. Phys. Lett., 306 (1999), 155,
O. A. Nerushev, R. E. Morjan, D. I. Ostrovskii, M. Sveningsson, M.
Jonsson, F. Rohmund and E. E. B. Champbell: Physica B 323 (2002),
51 and O. A. Nerushev, S. Dittmar, R. E. Morjan, F. Rohmund and E.
E. B. Champbell: J. Appl. Phys., 93 (2003), 4185).
[0011] It is tried to synthesize a nanotube using fullerene and a
multilayer thin film of a catalyst metal, and a structure
corresponding to a multi-walled nanotube is produced (E. Czerwosz,
P. Dluzewski, G. Dmowska, R. Nowakowski, E. Starnawska and H.
Wronka: Appl. Surf. Sci., 141 (1999), 350 and E. Czerwosz and P.
Dluzewski: Diamond Related Mater., 9 (2000), 901). After that, a
shocking paper that a single crystal of SWNT could be produced when
using C.sub.60 and a multilayer film of Ni was published on Science
by the group of Gimzewski et al. of IBM (R. R. Schlittler, J. W.
Seo, J. K. Gimzewski, C. Durkan, M. S. M. Saifullah and M. E.
Welland: Science, 292 (2001), 1136). Thereafter, however, it has
been apparent that a TEM image which is evidence for the above
paper is an image of molybdenum oxide (M. F. Chisholm, Y, Wang, A.
R. Lupini, G. Eres, A. A. Puretzky, B. Brinson, A. V. Melechko, D.
B. Geohegan, H. Cui, M. P. Johnson, S. J. Pennycook, D. H. Lowndes,
S. Arepalli, C. Kittrell, S. Sivaram, M. Kim, G. Lavin, J. Kono, R.
Hauge and R. E. Smalley: Science, 300 (2003), 1236b), and the group
of IBM also has announced that they accept the above fact (M. E.
Welland, C. Durkan, M. S. M. Saifullah, J. W. Seo, R. R. Schlittler
and J. K. Gimzewski: Science, 300 (2003), 1236c).
[0012] It is known that peapod in which fullerenes form a line in
the inside of SWNT is turned into DWNT by subjecting to heat
treatment at a high temperature (B. W. Smith, M. Monthioux and D.
E. Luzzi: Chem. Phys. Lett., 315 (1999), 31), and it is considered
that also in the above case, fullerenes in the inside have been
deformed into SWNT. Even if a nanotube formed in the inside is
SWNT, it is difficult to take it out, and only the same amount of
SWNT as that of SWNT which is originally present can be produced at
the most. Accordingly, it can not be technology for producing SWNT
from fullerene.
[0013] An object of the present invention is to produce SWNT having
a controlled diameter by a CCVD process.
DISCLOSURE OF THE INVENTION
[0014] The present invention relates to a process for producing
SWNT by a CCVD process, in which fullerens are used as a raw
material, and they are sublimated and brought into contact with a
heated catalyst to synthesize SWNT, wherein SWNT produced is
controlled in a diameter by fullerene used or chemically modified
fullerene used.
[0015] As described above, the present inventors consider that in
producing carbon nanotube by a conventional publicly known
technology using fullerene for a raw material, it is indispensable
to control a partial pressure of a fullerene gas in order to
produce a multi-walled carbon nanotube from fullerene, and the
present invention has come to be achieved.
[0016] First, at least one kind of fullerene C.sub.2n'S (n is an
integer of n.gtoreq.18, for example, C.sub.60, C.sub.70, C.sub.76,
C.sub.82 and the like) or chemically modified fullerenes is
sublimated at a sublimation temperature of the fullerene or higher
in a reaction apparatus evacuated to 0.5 Torr or less.
[0017] In respect to a vapor pressure of fullerene, conventional
experimental data are collected and reported in Table 3 of
Pankajavalli, Thermochimica Acta, 316 (1998), 101 to 108, and they
are shown in Table 1.
[0018] A vapor pressure of, for example, fullerene C.sub.60 can be
calculated from the following equation by referring to the above
and using an average of conventional experiments:
p(Torr)=7.5.times.10.sup.8.times.10.sup.-9500/T(K)
[0019] As one example, results obtained by calculating a vapor
pressure of fullerene C.sub.60 from the equation described above
are shown in Table 2. TABLE-US-00001 TABLE 2 Temperature
Temperature C.sub.60 vapor pressure (.degree. C.) (K) (Torr) 400
673 5.743E-06 450 723 5.437E-05 500 773 3.848E-04 550 823 2.147E-03
600 873 9.841E-03 650 923 3.824E-02 700 973 1.293E-01 750 1023
3.878E-01 800 1073 1.050E+00
[0020] The above sublimated fullerene gas is sent to a downstream
of a reaction apparatus using a vapor pressure thereof as a driving
force and brought into contact with a transition metal catalyst
carried on a thin film of a porous substance or an oxide of an
inorganic substance which is heated to a vaporization temperature
of the fullerene. SWNT is produced from fullerene by bringing
fullerene into contact with the catalyst. After prescribed time
passes since commencing the reaction, the reaction apparatus is
cooled to take out SWNT.
[0021] If a partial pressure of a fullerene gas (that is, a feeding
speed of fullerene) is suitable, fullerene is decomposed on the
surface of a catalyst particle and deposited on the surface in the
transition state of a carbon atom or molecule, and then a structure
having regularity is formed, whereby a single-walled carbon
nanotube can be deposited. This is because chirality of a carbon
nanotube deposited is considered to be determined according to the
direction and the position of a five-membered ring of a fullerene
molecule. Accordingly, a single-walled carbon nanotube in which
chirality is put in order can be produced in the present process in
which a part of a fullerene molecule can be remained on the surface
of a catalyst particle in an original form. A carbon nanotube
produced by the process of the present invention takes over the
regularity of a molecular structure of the fullerene, and therefore
a diameter distribution thereof can be narrowed.
[0022] However, a production condition of an elevated partial
pressure of fullerene gas (accelerating a feeding speed) can not be
a condition suited for producing a single-walled carbon nanotube.
This is because an amount of carbon staying in a transition state
is increased on the surface of a catalyst particle, whereby a
structure such as that of a multi-walled carbon nanotube in which
plural sheets having regularity are superposed is formed. Further,
it is because solid carbon is deposited before carbon atoms are
regularly arranged, so that amorphous carbon is produced.
[0023] In the process of the present invention, a single-walled
carbon nanotube is produced on a substrate having catalyst
particles in which particle diameters are uniformized. A size of
the catalyst particle is a factor for determining a diameter of a
single-walled carbon nanotube deposited from it, and therefore a
distribution of a diameter of the single-walled carbon nanotube can
further be narrowed by uniformizing a size of the catalyst
particle.
BRIEF DESCRIPTIONS OF THE DRAWINGS
[0024] FIG. 1 is a drawing showing a schematic diagram of a
production apparatus for SWNT prepared in Example 1.
[0025] FIG. 2 is a transmission electron micrograph of SWNT
produced in Example 1.
[0026] FIG. 3 is a Raman spectroscopic spectral chart of SWNT
produced in Example 1.
[0027] FIG. 4 is a drawing showing a schematic diagram of a
production apparatus for SWNT prepared in Example 2.
[0028] FIG. 5 is a Raman spectroscopic spectral chart of SWNT
produced in Example 2.
[0029] FIG. 6 is a drawing showing a schematic diagram of a
production apparatus for SWNT prepared in Example 3.
[0030] FIG. 7 is a drawing showing a heating curve of fullerene and
a change in a vapor pressure thereof in Example 3.
[0031] FIG. 8 is a transmission electron micrograph of SWNT
produced in Example 3.
[0032] FIG. 9 is a transmission electron micrograph of SWNT
produced in Example 3.
[0033] FIG. 10 is a Raman spectroscopic spectral chart of SWNT
produced in Example 3.
[0034] FIG. 11 is a Raman spectroscopic spectral chart of SWNT
produced in Example 4.
[0035] FIG. 12 is Raman spectroscopic spectral charts of SWNT
produced in Examples 3 and 4 and SWNT produced in Comparative
Example 1.
BEST MODE FOR CARRYING OUT THE INVENTION
[0036] FIG. 1 is a schematic drawing showing a production apparatus
for carrying out the present invention.
[0037] In the process of the present invention, at least one kind
of fullerene C.sub.2n's (n is an integer of n.gtoreq.18) or
chemically modified fullerenes is sublimated at a sublimation
temperature of the fullerene or higher in a reaction apparatus
controlled to a vacuum of 0.5 Torr or less, preferably 0.05 Torr or
less. A vaporizing part for fullerenes is in an effusion cell or a
quartz tube having a small diameter. Large flow resistance is
present between it and an outside reaction tube, and the internal
pressure thereof becomes approximately a vapor pressure of the
fullerene at a set temperature.
[0038] This sublimated fullerene gas is guided by means of a
straightening tube and brought into contact with a catalyst in a
downstream. In FIG. 1, the stream of the fullerene gas is
controlled by a method in which fullerene to be vaporized is put in
a closed side of a quartz tube sealed on one side and in which an
open end is turned to a vacuum device side to allow the heated and
vaporized fullerene to flow with a fullerene vapor pressure used as
driving force.
[0039] A pressure of the fullerene gas is controlled by a heating
temperature thereof, and it is important to control the
temperature. If a back pressure of the reaction apparatus is 0.05
Torr, a vapor pressure of fullerene has to be at the lowest 0.05
Torr which is equivalent to the back pressure, which requires it to
be heated at 660.degree. C. On the other hand, if the back pressure
is 0.5 Torr, it has to be heated at 760.degree. C.
[0040] It is reported that when a very pure solid of C.sub.60 is
heated in pure Ar for 10 minutes, thermal decomposition is
commenced at 959.degree. C. or higher and that the thermal
decomposition is almost completed at 977.degree. C. or higher (M.
R. Stetzer et al., Thermal Stability of C.sub.60, Phys. Rev. B. Vol
55 (1997). pp. 127 to 131). On the other hand, it is considered
that when a small amount of a solvent, other fullerenes such as
C.sub.70 and oxygen are present, the thermal decomposition proceeds
at a considerably lower temperature than that in the case described
above, and it is reported that the thermal decomposition already
proceeds, as shown in the following document, at 718.degree. C.
even if a raw material having a relatively high purity is used (Y.
Piacente et al., J. Phys. Chem., Vol 99 (1995). pp. 14052 to
14057).
[0041] Accordingly, it is considered that the decomposition of
C.sub.60 proceeds at 700.degree. C. or higher, and a temperature of
heating fullerene should have an upper limit, so that it is
preferred to reduce the back pressure and to lower the sublimation
temperature.
[0042] Fullerene moved from a vaporizing part collides with a
transition metal catalyst to become an initial nucleus of a
single-walled carbon nanotube while maintaining a part of the
molecular structure thereof, whereby the single-walled carbon
nanotube grows from the metal catalyst. It is considered that once
the initial nucleus is formed, SWNT is then relatively quickly
grown. Accordingly, a speed of elevating the temperature since
commencing vaporization of fullerene becomes important. The
catalyst is heated to a high temperature required for producing an
initial nucleus of SWNT from fullerene. The temperature is
preferably 750 to 900.degree. C.
[0043] A porous substance or an oxide of an inorganic substance is
coated or made into a film on a substrate which can stand the
operating temperature, and particles of at least one kind of a
metal are carried thereon. The sublimated fullerene described above
is allowed to pass on the substrate.
[0044] The transition metal is preferably any simple substance of
Fe, Co, Mo, Ni, Rh, Pd and Pt or a mixture thereof, and it is more
preferably Fe, Co or Mo. The smaller the diameter of the metal
particles, the better, and it is preferably 0.1 .mu.m or less, more
preferably 10 nm or less and further more preferably 3 nm or
less.
[0045] The porous substance shall not be restricted in a material
as long as it can carry the metal fine particles described above
and does not cause a change by a reaction temperature in the
apparatus, and it is preferably the porous body of a metal oxide or
other inorganic substance. Among them, the porous bodies of
zeolite, magnesia, alumina, silica and mesoporous silica are more
preferred, and Y type zeolite is particularly preferred. A thin
film of an inorganic oxide can also preferably be used, and a
silicon oxide film is particularly preferred.
[0046] The substrate on which the porous substance is carried or
the substrate on which an oxide film of an inorganic substance is
formed (hereinafter referred to as the substrate) is put parallel
to a flowing direction of a fullerene gas. Or, a plate worked to a
shape after the inner wall of the reaction tube is preferred.
[0047] The above substrate is cooled after prescribed time passes
since starting the production reaction. In respect to the cooling
method, heating of the reaction tube is stopped, and air of room
temperature is blown thereto from the outside by a fan to quickly
cool the reaction tube. After reaching the room temperature, the
substrate is taken out, and thus SWNT is obtained on the
substrate.
[0048] According to the above production process, SWNT having a
uniformized diameter can be obtained.
EXAMPLES
[0049] The present invention shall be explained below in further
details with reference to examples, but the present invention shall
not be restricted to the examples described below.
Example 1
[0050] As shown in FIG. 1, a quartz tube having an inner diameter
of 4.5 mm and a length of 200 mm in which one side was sealed and
which was filled in the sealed side with 500 mg of fullerene
C.sub.60 was disposed in a quartz tube (reaction tube) having an
inner diameter of 26 mm which was put in a heating furnace so that
a fullerene-filled part was positioned in the middle of the first
heating furnace. A quartz plate which was homogeneously coated
thereon with Y type zeolite particles (particle diameter: 0.3 to 1
.mu.m) carried thereon with Fe/Co catalyst fine particles (particle
diameter: 1 to 2 nm) was put parallel to a flowing direction in the
second heating furnace. The reaction tube was evacuated to 0.5 Torr
or less by means of a rotary pump. The first heating furnace has a
length of 20 cm, and the second heating furnace has a length of 30
cm. The first heating furnace was moved by 20 cm in an opposite
direction of the second heating furnace along the quartz tube, and
the first heating furnace and the second heating furnace were
heated to 850.degree. C. and 900.degree. C. respectively while
allowing argon to flow at 350 Torr and 200 sccm in the state that
fullerene was not heated. After heated, argon was stopped flowing,
and the reaction tube was evacuated again to 0.5 Torr or less.
Then, the first heating furnace was returned to the prescribed
position to start heating fullerene. After continuing the operation
for 10 minutes on the conditions described above, heating was
stopped, and air of room temperature was blown thereto by a fan to
cool the reaction tube. After cooled, the quartz plate coated
thereon with zeolite was taken out to obtain SWNT.
[0051] The sample prepared was subjected to supersonic wave
treatment in toluene to dissolve and remove fullerene, and then it
was observed under a transmission electron microscope (TEM) and
analyzed by Raman spectra.
[0052] A TEM photograph is shown in FIG. 2, and a Raman
spectroscopic spectra thereof are shown in FIG. 3.
[0053] It can be found from FIG. 2 that SWNT containing no
by-products and having a uniformized diameter is produced.
[0054] Observed in FIG. 3 are peaks (1590 cm.sup.-1) originating in
graphite and peaks in the vicinity of 150 to 300 cm.sup.-1 which
are characteristic of SWNT. Further, shown in the figure is a
diameter estimated from the relationship of a diameter of SWNT and
a Raman shift (Jorio et al., Phys. Rev. Lett., Vol. 86 (2001), pp.
1118): d(nm)=248/.nu.(cm.sup.-1) and it can be found that the
diameter is almost 1 nm.
Example 2
[0055] A schematic drawing of the apparatus used is shown in FIG.
4.
[0056] Operation was carried out in the same manner as in Example
1. The back pressure was controlled to 0.05 Torr, and used was a
quartz plate coated thereon with zeolite which was semi-cylindrical
after the inner wall of a reaction tube. A quartz tube in which
fullerene was sealed had the same diameter as that in Example 1 but
had a length reduced to 100 mm. Also, the first heating furnace was
controlled to a temperature of 680.degree. C., and the second
heating furnace was controlled to a temperature of 825.degree.
C.
[0057] Raman spectroscopic spectra of SWNT produced are shown in
FIG. 5.
Example 3
[0058] A schematic drawing of the apparatus used is shown in FIG.
6.
[0059] Operation was carried out in the same manner as in Example
2, and a quartz tube in which fullerene was sealed was equipped
with a thermocouple to measure a heating condition of SWNT.
[0060] Shown in FIG. 7 are a temperature change of the quartz tube
in which fullerene was sealed and a change in a vapor pressure of
fullerene since starting the experiment.
[0061] The TEM photographs of SWNT produced are shown in FIGS. 8
and 9, and Raman spectroscopic spectra thereof are shown in FIG.
10.
Example 4
[0062] Operation was carried out in the same manner as in Example
3, and fullerene C.sub.70 was substituted for fullerene C.sub.60 as
the raw material.
[0063] Raman spectroscopic spectra of SWNT produced is shown in
FIG. 11. It can be found that the similar SWNT to that in the case
of C.sub.60 is formed.
Comparative Example 1
[0064] Raman spectroscopic spectra of SWNT produced from alcohol by
a CCVD process are shown in FIG. 12.
[0065] Comparisons between a diameter distribution in SWNT produced
from alcohol and those in SWNTs produced in Example 3 (C.sub.60)
and Example 4 (C.sub.70) are shown by Raman spectroscopic spectra.
The number of peaks is large in SWNT produced from alcohol, and
diameter distributions of SWNTs produced from fullerenes are
apparently narrowed.
INDUSTRIAL APPLICABILITY
[0066] SWNT obtained by the present invention can widely be used
for an FED display, a fuel cell, an electron microscope, a ultra
high strength material and an electroconductive composite
material.
* * * * *