TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to a method for preparation of carbon peapod.
More particularly, the invention provides a new method for continuous high yield
5 synthesis of fullerene encapsulated in carbon nanotube structures. The present invention
also provides a new design and arrangement of the arc ablation unit used for the
synthesis of fullerene peapod carbon nanotube structure.
BACKGROUND AND THE PRIOR ART
10 The conductivity of C^o fullerene is generally low and this limits its applications in
electronic devices. On the other hand, CNTs have very good conductivity and
mechanical strength, which makes these materials attractive for electronic devices and
for imparting mechanical strength. Despite the huge potentials, the applications of
CNTs are still in laboratory scale in the field of electronic devices. This is mainly due to
15 the problem of tailor make the electronic properties and thermal conductivity of carbon
nanotube. The single walled carbon nanotube (SWCNT) could be either semiconducting
or metallic depending on their chiral angle and all the multi walled carbon nanotubes
(MWCNT) are metallic in nature due to the crossover of conduction and valance band at
room temperature. The synthesis of the carbon nanotube with the desired electronic
20 property and thermal conductivity during the growth of carbon nanotube is a big
challenge and thus limits its application in electronic industry. To address this issue of
carbon nanotube was subjected to chemical functionalization on its side wall or the
suitable elements/compounds were incorporated inside the carbon nanotube to tune its
electronic properties. The choice of functional moiety or the compound to chemically or
25 physically derivatize the nanostructure surface or to insert into the tube structure is
critical to achieve the tailor made the properties of the carbon nanotube derivatives.
It has been demonstrated and realized that the chemical functionalization damages the
sidewall of nanotube and makes them amorphous. The opto-electronic and mechanical
2
properties of the nanostructures would thus be significantly disturbed due to the
functionalization and hence the required electrical properties will not be achieved. On
the other hand a lot of different molecules/compounds have been coated onto the
surface of carbon nanotube and incorporated into the nanotube structure to tune its
5 electrical band gap. The coating of molecules or compounds onto the 1-D
nanostructures by the non-covalent interaction such as pi-pi interaction, van-der waals
interaction and static charge interaction is generally weak and does not significantly
alter the electronic properties of nanotube. The insertion of host molecules/compounds
inside the carbon nanotube by overcoming the strong van-der waals interaction by
10 keeping the nanotube structure intact is a challenge. It has been demonstrated that C6o
fullerene molecules could be successfully encapsulated inside the nanotube structure
due to the excellent compatibility and unique electronic features by heating them in a
sealed vacuum tube at high temperature to optimize the band structure of nanotube. The
amount of fullerene molecules insert into the nanotube structure will critically
15 determine by the ratio of fullerene to carbon nanotube, temperature of the insertion
process and the diameter of the nanotube and fullerenes.
Some non-patent literature are cited herein as reference:
1. M. S. Dresselhaus, G. Dresselhaus, P. C. Eklund, "Science of Fullerenes and
20 Carbon Nanotubes: Their Properties and Applications", Academic press,
Elsevier science, USA, 1996.
2. Teri Wang Odom, Jin-Lin Huang, Philip Kim, Charles M. Lieber, "Structure and
Electronic Properties of Carbon Nanotubes", J. Phys. Chem. B, 104, 2794-2809,
2000
25 3. Y. P. Sun, K. Fu, Y. Lin, W. Huang, Ace Chem Res., 35(12), 1096-1104, 2002.
Some patent documents are also referred herein below:
US2005164001 Al disclosed a hybrid material is provided which comprises a first
single-walled nanotube having a lumen, and a fill molecule contained within the lumen
30 of the single-walled nanotube. A method for producing the hybrid material is also
3
provided wherein a single-walled nanotube is contacted with a fill molecule to cause the
fill molecule to enter the lumen of the single-walled nanotube.
US2005100500 (Al) disclosed a high-density recording medium comprising a
5 fullerene/carbon nanotube complex (peapod) comprising a single-wall carbon tube in
which fullerenes are inserted in series. A structural difference between a locally bound
portion and a non-bound portion of the series of fullerenes is recorded as binary
information. The limit of storage capacity in conventional recording media based on
micrometer-level binarization information recording techniques can be overcome, and a
10 nano-scale binarization information recording technique is provided.
All the earlier processes of insertion of fullerenes into the carbon nanotube involves the
processes of the individual separate synthesis of carbon nanotube and fullerene and then
annealed them at a sealed vacuum tube at elevated temperature for several times to
15 insert the fullerene molecules inside the nanotube structures where there is no control
over the process of fullerene insertion into the nanotube structure. This process also
takes lot of time and thus limits the bulk production of fullerene peapod carbon
nanotube structures with optimized electrical and thermal conduction properties for the
electronic applications.
20
Therefore, the present invention provides a method for continuous high yield synthesis
of fullerene encapsulated in carbon nanotube structures and also provides a new design
of arc ablation chamber for the same. The total time to complete one full cycle of the
fullerene peapod structure is much less as compared to available conventional methods.
25
OBJECTS OF THE INVENTION
One of the objects of the present invention is to provide a method for the continuous
high yield synthesis of fullerene peapod carbon nanotube structures.
4
Another object of the present invention is to provide an arc ablation unit with the
tunable steady state transverse magnetic field to control the metal catalyzed nanotube
formation on the desired direction which is water cooled deposition plate.
5 Another object of present invention is to provide heating upto 500°C of the deposition
plate on which selectively nano materials could be deposited.
Yet another object of the present invention is to optimize the electrical and thermal
conductivity of nanotube by incorporation of the host molecules using the host-guest
10 interaction within the same arc reactor to achieve the high yield continuous production
of tailor made nanotube peapod structures in a much reduced reaction time.
These and other advantages of the present invention will become readily apparent from
the following detailed description taken in conjunction with the accompanying
15 drawings.
SUMMARY OF THE INVENTION
The following presents a simplified summary of the invention in order to provide a
basic understanding of some aspects of the invention. This summary is not an extensive
20 overview of the present invention. It is not intended to identify the key/critical elements
of the invention or to delineate the scope of the invention. Its sole purpose is to present
some concept of the invention in a simplified form as a prelude to a more detailed
description of the invention presented later.
According to an aspect of the present invention, there is provided a method for
25 continuous synthesis of fullerene encapsulated in carbon nanotube structure. The
method for continuous synthesis of fullerene encapsulated in carbon nanotube structure
comprises steps:
5
a) synthesizing a single or double walled carbon nanotube and essentially
depositing said single or double walled carbon nanotube on a deposition
plate,
b) removing by means of controlled heating of said deposition plate in presence
5 of air, a carbonaceous cap(s) formed during the synthesis step (a) from the
end of said single or double walled carbon nanotube, wherein said single or
double walled carbon nanotube become open ended
c) synthesizing fullerene(s) without breaking vacuum and essentially depositing
said fullerene(s) on said open ended single or double walled carbon nanotube
10 obtained from step (b) on said deposition plate,
d) inserting said fullerene(s) obtained from step (c) into said open ended single
or double walled carbon nanotube obtained from step (b) by heating said
fullerene(s) at vacuum.
15 In another aspect of the present invention, there is provided an apparatus for continuous
synthesis of fullerene encapsulated in carbon nanotube peapod structure. The apparatus
comprises:
an arc chamber with a cooling arrangement; said arc chamber being maintained
essentially vacuum;
20 means for feeding inert gas in said arc chamber;
an arc electrode arrangement comprising a cathode and plural anodes in said arc
chamber, wherein said anodes are movably located for facilitate selection of a suitable
anode for producing fullerene molecules inside said arc chamber;
a heater means for heating a deposition plate, wherein said deposition plate provided at
25 the top of said arc chamber for deposition of a single or double walled carbon nanotube
and a fullerene and
a magnetic field arrangement in said arc chamber wherein said magnetic field
arrangement is provided for controlling the direction of the metal nanoparticle
evaporation and deposition on said deposition plate.
6
Other aspects, advantages, and salient features of the invention will become apparent to
those skilled in the art from the following detailed description, which, taken in
conjunction with the annexed drawings, discloses exemplary embodiments of the
invention.
5
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The following drawings are illustrative of particular examples for enabling methods of
the present invention, are descriptive of some of the methods, and are not intended to
limit the scope of the invention. The drawings are not to scale (unless so stated) and are
10 intended for use in conjunction with the explanations in the following detailed
description.
Figure. 1 illustrates the schematic design of the arc ablation system and conventional arc
system for the continuous high yield peapod productions.
Figure.2 illustrates the schematic representation of the process steps for the continuous
15 high yield peapod productions.
Figure.3 illustrates the molecular dynamics study of the peapod formation using
computer modeling by HyperChem software.
Figure.4 illustrates the TEM images of the DWCNT (A) on the aluminum plate,
fullerene deposited on the DWCNT (B) and fullerene molecules inserted into the
20 DWCNT (C).
Figure.5 illustrates the front view of the Arc Ablation System Electrode layout.
Figure.6 illustrates the side view of the Arc Ablation System Electrode layout.
Figure.7 illustrates the magnet arrangement between the electrodes.
Figure.8 illustrates the MIMIC software screen first step.
25 Figure.9 illustrates the MIMIC software screen second step.
7
Figure. 10 illustrates the MIMIC software screen third step.
Persons skilled in the art will appreciate that elements in the figures are illustrated for
simplicity and clarity and may have not been drawn to scale. For example the
dimensions of some of the elements in the figure may be exaggerated relative to other
5 elements to help to improve understanding of various exemplary embodiments of the
present disclosure.
Throughout the drawings, it should be noted that like reference numerals are used to
depict the same or similar elements, features and structures.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
10 The following description with reference to the accompanying drawings is provided to
assist in a comprehensive understanding of exemplary embodiments of the invention as
defined by the claims and their equivalents. It includes various specific details to assist
in that understanding but these are to be regarded as merely exemplary.
Accordingly, those of ordinary skill in the art will recognize that various changes and
15 modifications of the embodiments described herein can be made without departing from
the scope and spirit of the invention. In addition, descriptions of well-known functions
and constructions are omitted for clarity and conciseness.
The terms and words used in the following description and claims are not limited to the
bibliographical meanings, but, are merely used by the inventor to enable a clear and
20 consistent understanding of the invention. Accordingly, it should be apparent to those
skilled in the art that the following description of exemplary embodiments of the present
invention are provided for illustration purpose only and not for the purpose of limiting
the invention as defined by the appended claims and their equivalents.
It is to be understood that the singular forms "a," "an," and "the" include plural
25 referents unless the context clearly dictates otherwise.
By the term "substantially" it is meant that the recited characteristic, parameter, or value
need not be achieved exactly, but that deviations or variations, including for example,
8
tolerances, measurement error, measurement accuracy limitations and other factors
known to those of skill in the art, may occur in amounts that do not preclude the effect
the characteristic was intended to provide.
Features that are described and/or illustrated with respect to one embodiment
5 may be used in the same way or in a similar way in one or more other
embodiments and/or in combination with or instead of the features of the other
embodiments.
It should be emphasized that the term "comprises/comprising" when used in this
specification is taken to specify the presence of stated features, integers, steps or
10 components but does not preclude the presence or addition of one or more other
features, integers, steps, components or groups thereof.
Accordingly, the present invention provides a method for continuous synthesis of
fullerene encapsulated in carbon nanotube structure and corresponding apparatus
thereof.
15 In present invention there is provided a method for the continuous high yield synthesis
of the fullerene peapod structures by designing a suitable arc ablation unit. The
complete one cycle to produce the fullerene peapod structure consists of four steps and
this cycle could be repeated any number of times to increase the yield of peapod
structures in layer by layer on the aluminum plate as described in figure. 1. The
20 fabrication of peapod structure first involves the synthesis of SWCNT or DWCNT
where the d block metal sulfide impregnated anode is used. It has been found that for
the fabrication of lower diameter nanotube (SWCNT or DWCNT), the metals salt are
required to catalyze the growth of nanotube in arc method. The iron, nickel and cobalt
are the most used catalyst to grow carbon nanotube and the addition of the small amount
25 of sulfur is found to promote the growth of SWCNT/DWCNT. The phase diagram of
carbon, metal and sulfur suggests a broadening of temperature zone which provides an
ideal condition of SWCNT/DWCNT growth in arc plasma. The replacement of Helium
by argon and hydrogen mixture also helps to increase the SWCNT/DWCNT production
by increasing the temperature of the arc plasma. The iron/nickel/cobalt in nanoform are
9
magnetic in nature and evaporate in the transverse direction of the arc carbon plasma
due to the application of in built Lorentz force and thus all metal nanoparticles catalyzed
nanotubes are deposited on the chamber wall of the arc ablation system. We have
introduced an external magnetic field to control the direction of the metal nanoparticles
5 evaporation and deposit the corresponding SWCNT/DWCNT on the water cooled
aluminum plate (figure. 1).
The carbon nanotube produced in arc always comes with the closed cap of either metal
of carbonaceous material due the nanotube nucleation on the metal nanoparticles
dissolved in the pool of liquid carbons. It thus required removing the cap from the two
10 ends of nanotube to introduce fullerene into nanotube structure. In the second step, the
capping from the carbon nanotubes is removed by heating them in air at the controlled
atmosphere using mass flow controller. The heating coils under the Aluminum plates
provide us the opportunity to heat the aluminum plate at a desired temperature by
controlling the current flow through the heating coils (figure. 1).
15 The present invention provided a turret on the calottes where multiple anodes could be
introduced and a new anode could be selected without breaking the vacuum. In the third
step we have select an anode which comprises of only graphite to produce fullerene
molecules on the open ended carbon nanotube at the water cooled aluminum plate. The
helium atmosphere pressure in the arc ablation system has been controlled to reduce the
20 concentration of carbon ions in arc plasma to produce a conductive atmosphere for
fullerene growth. The ratio of the fullerene to carbon nanotube is controlled by the
duration of the arcing to produce fullerene molecules on the open ended carbon
nanotube at the water cooled aluminum plate (figure. 1).
In the final step the fullerene molecules on the carbon nanotubes is heated at a very high
25 vacuum to insert fullerene into the carbon nanotube structures. The process parameters
have been schematically illustrated in Figure.2 for better clarity.
A computer based molecular dynamic studies were carried out to theoretically identify
the required temperature and the duration to insert a fullerene molecule inside the
nanotube. It is always advantageous to theoretically determine the optimal parameters
30 for the peapod synthesis using fullerene and open ended carbon nanotube and hence the
10
theoretical molecular dynamics study of the insertion of fullerene into the carbon
nanotube process is carried out using computer modeling by HyperChem software (Fig
3).
The products obtained at each step are characterized by the analytical techniques like
5 Raman, TGA and TEM (Fig 4).
Method steps involved in continuous synthesis of fullerene encapsulated in carbon
nanotube structure
1. In the first step, synthesized the single and double walled carbon nanotube and
selectively deposited them on the water cooled aluminum plate by using the
10 tunable external magnetic field and composite graphite rod of iron, nickel,
cobalt, sulphur and carbon in the ratio of 1.4:2.6:0.7:0.75:94.5 as anode.
2. In the second step, removal of the carbonaceous cap from the two end of carbon
nanotube by controlled heating of the aluminum plate in presence of desired
amount of air which is controlled by the mass flow controller.
15 3. In the third step, fullerenes are synthesized by selecting the desire anode by
rotating the turrets of the calotte to choose the suitable pure graphitic electrode
and deposited these fullerenes on the open ended carbon nanotube on the water
cooled aluminum plate. The amount of fullerene deposited on the nanotube, i.e.
the ratio of fullerene and carbon nanotube is controlled and optimized by the
20 duration of the arcing for producing fullerene.
4. In fourth step, the fullerenes are forced to enter into the carbon nanotube from
the open end by heating them at vacuum.
25 DESCRIPTION OF THE INSTRUMENT:
Arc Chamber:
Cylindrical arc chamber is designed and fabricated as doubly jacketed Arc chamber.
Design layout of the chamber with multiple electrode system is shown in Fig 5 as front
view and in Fig. 5 as side view. It is designed to withstand high arc temperature by
30 suitable water based cooling system. Separation between the layers is 10mm ±5% and
11
welded at ends to eliminate any water leakage. Arc chamber dimension is 300 mm
internal diameter (I.D) 327 mm external diameter, length is 500mm. thickness of inner
cylinder is 2mm and 1.3 mm outer cylinder. Inter cylinder space is filled with water
completely. Water inlet is provided at the lower side of cylinder and water out is at the
5 top of cylinder. Stainless steel tubular ring water cooling system is not suitable because
it will have two major disadvantages -
1. Welding of the stainless steel tubing on the cylinder will deform tube as well as
internal chamber of the electrical arc chamber.
2. It will not able to provide adequate effective cooling to the electrical arc chamber for
10 maintaining optimum operational chamber temperature.
Flow rate of cooled water to the arc ablation inter cylinder space is 15 liters/ minutes.
Connecting tube internal diameter is 8mm and tube is made of poly urethane. For
achieving required flow rate of cooling water, magnetic drive pump is installed. View
port is provided to the arc chamber at front side and circular quartz window is fitted.
15 Arc ablation chamber is designed to withstand ultimate pressure of 10"6 mbar, but
minimum process pressure required is only 10"3 mbar for evacuation of the chamber.
Vacuum System:
Arc chamber is connected with direct drive rotary pump, 500 liters/ minute pumping
capacity and direct drive root pump, 400 m3/hr pumping capacity. Direct drive root
20 pump is required because direct drive rotary pump is not capable of creating 10"3 mbar
pressure under loading condition. Piranni gauge is provided to measure ultimate
evacuation pressure which lies in the range of 10"3 mbar. Dial gauge is attached with
chamber for monitoring process operation pressure range.
Gas purging inlet is provided for gas purging process or other gases into chamber. Gas
25 flow rate is controlled by mass flow controller 0-100 seem. Sevenstar made, which
work on thermal principle and installed on the front operation panel. Gas flow rate can
be adjusted by rotating the knob. Chamber vent valve is provided with chamber to bring
it on atmospheric pressure and rotary went valve is provided to isolate chamber from
vacuum system.
12
Arc Electrode
One cathode and four coupled anode is provided inside arc chamber. Position of the
cathode is fixed while anode is equipped for linear movement as shown in Fig 5 and Fig
6. Linear movement is controlled by stepper motor. Stepper motor speed is controllable
5 and can also be programmed. In auto run mode the motor speed is 0.67mm/sec. four
coupled anode is also equipped with 4 step rotary A.C. motor. Precise anode position is
determined and controlled by Autonix proximity sensor fitted on the chamber. Cathode
and anode both are water cooled and main housing is made of stainless steel. Cathode
tip is made of copper and having diameter 20 mm and an adjustable hole in side for
10 holding 6 mm or 8 mm cathode rod. Anode tips are also made of copper and capable to
hold 6 mm or 8 mm graphite or other material rod.
Heater and Top Deposition Plate:
Nichrome heater is installed in the Arc Ablation Chamber for heating the deposition
plate. Deposition plate is made of stainless steel 304 L and fitted on the top of the
15 chamber. This heater is capable to heat the deposition plate up to 450 °C which can be
controlled by the temperature controller, make- Fujicon, by setting up process values.
Heater plate dimension is 100 mm diameter and deposition plate diameter is same. In
order to hold vacuum, the heater assembly is sealed by neoprene O ring.
Magnetic field arrangement:
20 Magnetic field arrangement is provided perpendicular to cathode and anode plane by
two external electromagnetic poles as shown in Fig 7. These assemblies can create a
magnetic field of 1 tesla intensity. Magnetic field can be controlled by current flowing
through solenoid magnetic coils. Constant current power supply is provided in the
system which delivers current to the solenoid at 90 volts D.C. for supplying and
25 controlling required amount of current. Current limit of the module is 6 ampere.
Arc Power Supply:
13
Power supply is designed to deliver O/P power at 33 volts D.C. and current up to 300
ampere. Power supply draws power from 220 volts, single phase A.C. mains. Arc power
supply consists of 5 main modules-
1. Relay based contactor
5 2. Variable transformer
3. Primary- secondary transformer.
4. AC to DC converter circuit
5. Output stage
Chiller Unit:
10 Electrical Arc Ablation System is cooled by cold water circulation arrangement. Chiller
is the main driving equipment of cooling arrangement. It consists of condensing unit,
compressor unit operated on 230 volts, 50 Hz, single phase, 12 ampere. Compressor of
the chiller compresses the Freon gas filled inside. During this heat is released. High
pressure gas is released through nozzle which cools down heat exchanger in contact
15 with circulating water. Main supply passes through 25 ampere MCB. Temperature
indicator and control and ON-OFF indicators are installed on front side. Temperature of
the outgoing water can be set. Compressor rated capacity is 2 tons. Gas dryer is also
fitted to remove moisture present in circulating water. Magnetic/ chemical drive pump
is for pumping or circulating water. Magnetic drive pump is having advantage against
20 leak in compression in comparison to normal pump. No moving part comes out through
seal which degrades over the time. J-type thermocouple is suspended in water for
physical temperature measurement. Output of this thermocouple makes it to ON-OFF.
Exhaust fan is also provided to accelerate cooling action.
14
Electrical Console:
Arc ablation System operates on three phase power supply. It consumes 10 kW power
excluding chiller unit. Direct drive rotary pump and direct drive root pump are three
5 phase. Electrical control panel operates at single phase. Main power supply enters the
system at electrical contactor point. One of the phases reaches latch push NO switch.
This NO push switch and latch are in parallel connection. Then phase goes to push off
NC switch i.e. push OFF NC switch and push ON NO switch are connected in series.
This phase line actuates the electrical contactor coil and makes contactor ON or OFF.
10 All the three phases' line of main supply goes to 32 ampere fuse. These fuses are used
to protect the instrument from accidental short circuit or overloading. There are three
phase lines indicator lamp mounted on the front panel of the instrument. This indicates
the presence of all the three phases of the power supply.
Power lines are distributed for direct drive rotary pump motor, direct drive root pump
15 motor, heater and process module through MCB-1 (16 ampere, 3 phase), MCB-2 (16
ampere, 3 phase), CB-3 (16 ampere, single phase) and MCB-4 (16 ampere, single
phase) respectively. Output of the MCB-1 goes to electrical contactor C-2 through fuses
of 16 ampere rating value. Contactor is operated/ controlled by program logic controller
(PLC) which makes contactor ON or OFF depending upon the user or auto sequence
20 requirement. If contactor C-2 is ON all three phase lines power reaches the direct drive
rotary pump motor and make it operational.
Output of the MCB-2 goes to contactor C-3 through fuses of 16 ampere rated capacity.
Contactor is operated through PLC which turns contactor ON or OFF. If the contactor
C-3 is ON, all the three phases power reaches to direct drive root pump motor and make
25 it operational. Interlocking circuitry is provided between direct drive rotary pump and
direct drive root pump. So that root pump can only be started if rotary pump is already
ON. This arrangement is necessary for the protection of direct drive root pump, which
may be damaged otherwise.
15
Output of the MCB-3 goes to electrical contactor C-4 through fuse. Again the contactor
C-4 is controlled/ operated by PLC. If the electrical contactor is ON, the power supply
reaches heater. Heater power supply is independent of other process parameter i.e. it can
be ON or OFF at any time.
5 Output of the MCB-4 goes to electrical contactor C-5 through fuse of 16 ampere rated
capacity. This electrical contactor is also controlled by PLC and power supply to
process module can be available only when this contactor is at ON position. It can ONOFF
at any time in manual operation mode but in automatic mode, it can be ON only
when direct drive rotary and direct drive root pump are in ON condition.
10 Computer Interface:
Arc ablation system is automated and controlled by computer where MIMIC software is
installed. PLC FINIX 24 of Mitsubishi make and SCADA of Siemens make are used for
automatic control of arc ablation system. All the process parameters are controlled by
computer. As we select MIMIC software MIMIC screen will appear as shown in Fig 8
15 and as we proceed further screen will appear as shown in Fig 9 and Fig 10, on the
computer monitor which shows the running/ current status of the Arc Ablation System.
Before proceeding to any arc operation we have to initialize the system by homing
action for which soft switch is present in MIMIC screen. MIMIC screen shows the text
that describes the homing ON and its status.
20 Once homing is complete, vacuum button has to be selected and then START switch
and after this text will appear that system is ready for process. Direct drive rotary pump
starts at first and after 1 minute delay direct drive root pump will start. Process switch is
selected for making process module ON and the MIMIC screen will display the running
status of the process parameters like the anode number selected for arc, arc current and
25 time spent in arcing etc. Heater temperature is also displayed in degree Celsius. Start
and stop button is provided for starting a cycle and stopping of a currently running cycle
or operation. All above process start will subject to the proper functioning of chiller,
water flow, door close, phase loss and vacuum.
16
Operation switches: User can turn ON and OFF the switches by clicking on the
particular button. Manual operation involve basically three stages of arcing-
1. Homing- In homing, the anode will reach to its initial position irrespective of its
current position. This action is essential for starting of a fresh cycle.
5 2. Vacuum- Direct drive rotary pump button is selected for making it ON. After
some delay direct drive root pump button has to be selected for making it ON. If
user first select direct drive root pump, it would not work for root pump
protection reason. System will become ready for arcing if vacuum stage is
completed successfully.
10 3. Arc Process- Mass flow Controller (MFC) power supply and magnet power
supply is turn ON by selecting suitable switches and selected anode will be
arced. One has to repeat all the above mentioned process stages for start of a
fresh cycle.
Software program automatically save all process parameter data in the form of excel
15 sheet. These data can be retrieved by clicking search option and appear on the computer
monitor.
Applications:
The present invention have its electronic applications and other potential applications in
such as photovoltaics, sensors, field emission, light emitting diodes, smart textile &
20 conducting fibers, field effect transistors and non-volatile random access memory for
molecular computing devices.
17

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WE CLAIM:
1. A method for continuous synthesis of fullerene encapsulated in carbon nanotube
5 structure, said method comprising steps of:
(a) synthesizing a single or double walled carbon nanotube and essentially
depositing said single or double walled carbon nanotube on a
deposition plate,
(b) removing by means of controlled heating of said deposition plate in
10 presence of air, carbonaceous cap(s) formed during the synthesis step
(a) from the end of said single or double walled carbon nanotube,
wherein said single or double walled carbon nanotube become open
ended
(c) synthesizing fullerene(s) without breaking vacuum and essentially
15 depositing said fullerene(s) on said open ended single or double
walled carbon nanotube obtained from step (b) on said deposition
plate,
(d) inserting said fullerene(s) obtained from step (c) into said open ended
single or double walled carbon nanotube obtained from step (b) by
20 heating said fullerene(s) at vacuum.
2. The method as claimed in claim 1, wherein deposition of said single or double
walled carbon nanotube on said deposition plate is attained by controlling the
direction of said single or double walled carbon nanotube formation using a
25 magnetic field arrangement.
3. The method as claimed in claim 1, wherein controlled heating of said deposition
plate is provided by controlling a current flow through a heating coil provided
under said deposition plate.
30
18
^ o
10
F
€ \ *
4. The method as claimed in claim 1, wherein ratio of fullerene to carbon nanotube
in the arc chamber is controlled and optimized by the duration of the arcing for
producing said fullerene(s).
5. The method as claimed in claim 1, wherein said deposition plate is an aluminum
plate.
6. The method as claimed in claim 1, wherein said magnetic field arrangement
comprises two electromagnetic pole(s) perpendicular to an arc electrode
arrangement in said arc chamber.
7. The method as claimed in claim 6, wherein said arc electrode arrangement
comprises a cathode and multiple coupled anode in said arc chamber.
8. An apparatus for continuous synthesis of fullerene encapsulated in carbon
15 nanotube peapod structure, said apparatus comprising:
an arc chamber with a cooling arrangement; said arc chamber being
maintained essentially vacuum;
means for feeding inert gas in said arc chamber;
an arc electrode arrangement comprising a cathode and plural anodes in said
20 arc chamber, wherein said anodes are movably located for facilitate selection
of a suitable anode without breaking the vacuum for producing fullerene
molecules inside said arc chamber;
a heater means for heating a deposition plate, wherein said deposition plate
provided at the top of said arc chamber for deposition of a single or double
25 walled carbon nanotube and a fullerene and
a magnetic field arrangement in said arc chamber wherein said magnetic
field arrangement is provided for controlling the direction of the metal
nanoparticle evaporation and deposition on said deposition plate.
30 9. The apparatus as claimed in claim 8 further comprising a chiller unit for driving
said cooling arrangement provided in said arc chamber.
19
10
15
5
10. The apparatus as claimed in claim 8, wherein said deposition plate is an
aluminum plate.
11. The apparatus as claimed in claim 8, wherein said magnetic field arrangement
comprises two electromagnetic pole(s) perpendicular to said arc electrode
arrangement in said arc chamber.
12. The apparatus as claimed in claim 8, wherein said anodes are located on a
rotatable turret.
13. The apparatus as claimed in claim 12 further comprising a stepper motor
connected to said turret for controlling the forward movement of the anode to
control the rate of evaporation of the said anode without breaking vacuum in
said arc chamber.
14. The apparatus as claimed in claim 8, wherein said arc chamber is double
layered.
15. The apparatus as claimed in claims 8 and 14, wherein said cooling arrangement
20 is provided by filling water in the intermediate space between said outer and
inner layers of the arc chamber.