JPH0733419A - Method and apparatus for collecting carbon 60 - Google Patents

Abstract

PURPOSE:To easily and efficiently capture C60 molecules by arranging a filter which allows passage of the C60 molecules but captures amorphous carbon particles and a collecting means for sticking the crystals of C60 in a specific manner. CONSTITUTION:An inert gaseous atmosphere of about 100Torr is formed within a bell-jar 10. Smoke contg. the C60 molecules of a high concn. past a first net 12 rises together with the convection of the gas and arrives at a second net 13. The temp. of the smoke is about 300 to 350 deg.C in the region of the second net 13 and is the temp. suitable for crystallization of the C60 molecules. Then, the C60 molecules are crystallized on the second net 13 and are stuck to the net 13. The net 13 is recovered at the point of the time when the specified amt. of soot sticks to the second net 13. The soot of the net 13 is dropped by a brush and is collected, by which the C60 is easily collected. The amorphous carbon particles and the C60 are easily separately collected according to the height from carbon electrodes according to such device.

Description

Detailed Description of the Invention

[0001]

2. Description of the Related Art Carbon 60 (hereinafter referred to as "C ₆₀ ")
Is for forming a superconducting salt having a relatively high transition temperature T _c such as K ₃ C ₆₀ (19.28), K ₂ RbC ₆₀ (21.8) (transition temperature (K) in parentheses). , Has been attracting attention in recent years,
Methods for collecting C ₆₀ are already known. This C
According to the ₆₀ collection method, soot is first collected by the gas evaporation method. The soot contains about 10% of C ₆₀ molecules, and the remaining about 90% is amorphous carbon particles. The collected soot is dissolved in an organic solvent such as benzene or toluene. At this time, the amorphous carbon particles are insoluble in the organic solvent, but the C ₆₀ molecules are soluble in the organic solvent. Therefore, the C ₆₀ molecule is separated and then purified by removing the organic solvent in which the C ₆₀ molecule is dissolved.

The collection of soot by the in-gas evaporation method will be briefly described below. A pair of carbon rods for arc discharge are arranged in a bell jar, and arc discharge is performed in an inert gas atmosphere of about 100 Torr to heat the carbon rod. At this time, the carbon rod reaches a temperature of 3000 ° C. or higher, and carbon vapor generated from the carbon rod near the carbon rod collides with gas molecules in the atmosphere and condenses to form clusters, and the vapor is adsorbed on the clusters. It grows in phase to become solid particles (soot).
Then, the soot rises with the convection of the gas and forms smoke. The soot is collected by attaching it to an appropriate means, for example, the inner surface of a bell jar or a glass plate arranged above the carbon rod.

However, this collection method is very laborious and very inefficient, and at present, it is only possible to collect about 100 to 150 mg of C ₆₀ molecules in a day's work. Therefore, 1 g of C ₆₀ molecule currently costs tens of thousands of yen in the market.

[0004]

OBJECTS OF THE INVENTION It is therefore an object of the present invention, in order to overcome the drawbacks of the collection method of the conventional C _60, C ₆₀
It is an object to provide a method and a device capable of collecting molecules easily and efficiently, and thereby to provide C ₆₀ molecules at low cost.

[0005]

In the gas evaporation method, the present inventor measured the temperature of smoke generated from a carbon rod as a function of the height from the carbon rod. As a result of the measurement, it was found that the temperature of the smoke dropped sharply as the smoke rose, and at the point about 60 mm above the carbon rod, the temperature of the C ₆₀ molecule had already dropped to the degree of crystallization. did. Then, by utilizing this temperature characteristic, it was conceived that C ₆₀ and amorphous carbon particles can be easily separated and collected in relation to the height from the carbon rod.

That is, according to the present invention, a pair of carbon electrodes for arc discharge are arranged in an inert gas atmosphere to perform arc discharge, and molecules of carbon 60 in the convection of smoke generated from the pair of carbon electrodes are crystallized. A filter means for allowing the molecules of the carbon 60 to pass therethrough but trapping the amorphous carbon particles is arranged in a temperature range where the carbon 60 molecules are crystallized on the downstream side of the filter means in the smoke convection. The carbon 60 in the temperature range
The method for collecting the carbon 60 is configured by arranging a collecting means for adhering the crystals of the above.

At this time, the filter means is arranged in a temperature range of 400 to 500 ° C. in the convection of the smoke,
The collecting means is operated at a temperature of 300 to 3 during the smoke convection.
It is preferably arranged in the region of 50 ° C. Further, in order to achieve the filter function without disturbing the convection of gas, that is, the convection of smoke as much as possible, it is preferable that the filter means is composed of a net.

Further, as an apparatus suitable for carrying out the above-mentioned method, a vacuum chamber, a pair of carbon electrodes for arc discharge arranged inside the vacuum chamber, and an external unit connected to the pair of carbon electrodes. A power source, a filter means arranged above the carbon electrode inside the vacuum chamber, for allowing molecules of the carbon 60 to pass therethrough, but capturing amorphous carbon particles, and above the filter means inside the vacuum chamber. Collecting means for adhering the crystals of carbon 60 disposed in the vacuum chamber, a vacuum pump connected to the vacuum chamber, an inert gas supply means connected to the vacuum chamber, and a vacuum gauge connected to the vacuum chamber. And the filter means is arranged in a temperature range in which molecules of carbon 60 in the convection of smoke generated from the pair of carbon electrodes during arc discharge do not crystallize. The collection means is configured to apparatus for collecting carbon 60, characterized in that the molecules of carbon 60 in the convection of the smoke is arranged in a temperature region of crystallization.

Preferably, the filter means comprises a net. Also, the net has a dome shape,
It is preferable that the opening of the dome is arranged so as to face the carbon electrode. Furthermore, it is preferable that the filter means is arranged in a region of a temperature of 400 to 500 ° C. in the convection of the smoke, and the collecting means is arranged in a region of a temperature of 300 to 350 ° C. in the convection of the smoke. .

[0010]

In the structure of the present invention, the smoke generated from the carbon compact rises with the convection of the gas. When the smoke passes through the filter means, most of the amorphous carbon particles contained in the smoke are trapped by the filter means, but C _{60 which} remains in a molecular state without being crystallized causes the filter means to pass through the filter means. pass. The smoke containing a large amount of C ₆₀ further rises with the convection of gas and reaches the collection means. Then, here, the C ₆₀ molecules are crystallized and attached to the collecting means.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic diagram illustrating a method for collecting C _{60 according} to the present invention. In FIG. 1, when a pair of carbon electrodes 1 are placed in an atmosphere of an inert gas of about 100 Torr and heated by, for example, an arc discharge, the carbon electrode 1 reaches a temperature of 3000 ° C. or higher, and in the vicinity of the carbon electrode 1. Carbon vapor generated from the carbon electrode 1 collides with gas molecules in the atmosphere and condenses to form clusters. Then, carbon vapor is adsorbed on the clusters, vapor-phase-grown into solid particles (soot), and the soot rises with the convection of the gas due to heating to form smoke 2.

At this time, when the temperature of the smoke 2 is measured as a function of the height from the carbon electrode 1, the graph shown in FIG. 3 is obtained. As is clear from this graph, as the smoke 2 rises, the temperature of the smoke 2 sharply decreases.
By utilizing this temperature characteristic, amorphous carbon particles and C ₆₀ can be separated and collected in relation to the height of the carbon electrode 1.

[0013] That is, the temperature region where the molecules of C ₆₀ not crystallize during convection of smoke, the molecules of C ₆₀ is the amorphous carbon particles is passed is disposed a filter unit 3 for capturing, further in a convection smoke In the temperature region where the C ₆₀ molecules crystallize on the downstream side (upper side) of the filter means in
A collecting means 4 for depositing ₆₀ crystals is arranged. In this case, the filter means 3 is preferably one that can achieve the desired filter function without disturbing the convection of smoke as much as possible, and for example, the first net having a mesh of a certain size is used. The collecting means 4 may be any as long as it can attach C ₆₀ crystals, but like the filter means 3, it is preferable that the convection of the gas is not disturbed as much as possible, and for example, a fixed amount. A second net with a size mesh is used.

Thus, the smoke generated from the carbon electrode 1 is
It rises with the convection of gas. When the smoke passes through the first net 3 (filter means), most of the amorphous carbon particles in the smoke are attached to and trapped on the first net 3, but the C ₆₀ molecules are It goes through the mesh of the first net 3 and further rises toward the second net 4. Then, it crystallizes on the second net 4 and adheres to the net 4. When a certain amount of soot is attached to the second net 4, the second net 4 is collected, and the attached soot is removed by a brush to collect C _60, so that C ₆₀ can be easily obtained. If the first net becomes clogged during the collection, the soot attached by a brush or the like may be appropriately removed.

In order to confirm whether or not the amorphous carbon particles and C ₆₀ are actually separated and collected by the above-mentioned method, the material collected by the first net 3 and the material collected by the second net 4 are collected. The electron microscope image and the diffraction image were examined. As a result, it was found that most of the collected matter from the first net was amorphous carbon particles and that of the second net matter was mostly crystallized C ₆₀ .

FIG. 2 shows an example of a device suitable for carrying out the method according to the invention. As shown in FIG. 2, the device has a cylindrical bell jar 10. A pair of carbon rods 11 for arc discharge are horizontally arranged in the lower portion of the bell jar 10, and the stainless steel upper lid 10 of the bell jar 10 is arranged.
supported by a. One of the carbon rods 11a is formed so that the tip has a smaller diameter than the remaining portion,
In addition, the opposite end surfaces of the pair of carbon rods 11 are in contact with each other. In this case, the front end surfaces of the pair of carbon rods 11 may be placed in pairs at appropriate intervals. The pair of carbon rods 11 are connected to a discharge external power supply 17.

Inside the bell jar 10, a dome-shaped first net 12 made of stainless steel is provided above the carbon rod 11.
The opening is made to face the carbon rod 11, and the upper lid 10a of the bell jar 10 is made by an appropriate member (not shown).
Supported by. The first net 12 is about 2-3 mm
It has a mesh. A flat plate-shaped second stainless net 13 is horizontally arranged above the first net 12 inside the bell jar 10, and is supported by the upper lid 10a of the bell jar 10 by an appropriate member (not shown). There is. The second net 13 has a mesh of about 1 mm.

The first net 12 and the second net 13
Are arranged at height positions that are predetermined based on the temperature characteristics of smoke generated from the carbon rod 11 during arc discharge. That is, the first net 12 has a smoke temperature of about 40
At a height position of 0 to 500 ° C., the second net 13 is
It is arranged at a position where the temperature of smoke is about 300 to 350 ° C.

The lower lid 10b of the bell jar 10 is provided with a vacuum pump 14 for drawing a vacuum inside the bell jar and an inert gas storage device 15 for introducing an inert gas into the bell jar, which are valves 18 and 19, respectively. Connected through. Further, the lower lid 10 of the bell jar 10
A vacuum gauge 16 for measuring the degree of vacuum inside the bell jar is connected to b.

The method of operating this device will be described below. First, the vacuum pump 14 is operated, and the inside of the bell jar 10 is evacuated. When the inside of the bell jar is in an appropriate vacuum state, the valve 18 is closed, while the valve 19 is opened, so that the inert gas storage device 1
Inert gas is introduced into the bell jar from 5. At this time, the gas pressure of the introduced inert gas is measured by the vacuum gauge 16. In this way, inside the bell jar 10,
An inert gas atmosphere of about 100 Torr is formed.

After that, arc discharge is performed. Due to the arc discharge, the carbon rod 11 is heated to 3000 ° C. or higher,
Smoke is generated from the carbon rods 11 and rises toward the first net 12 along with the convection of the gas generated inside the bell jar. The temperature of smoke is about 400-in the area of the net 12.
500 ° C., at which temperature C ₆₀ is still in the molecular state. Therefore, the C ₆₀ molecules pass through the mesh of the first net 12 and further rise, but the amorphous carbon particles are
Attached to the net 12. Thus, the first net 12
This removes most of the amorphous carbon particles in the smoke.

A high concentration of C ₆₀ which has passed through the first net 12
The smoke containing molecules rises with the convection of the gas and reaches the second net 13. The smoke temperature is about 300 to 350 ° C. in the region of the second net 13, which is a temperature suitable for crystallization of C ₆₀ molecules. Therefore, the C ₆₀ molecules crystallize on the second net 13 and attach to the net 13.
When a certain amount of soot is attached to the second net 13, the net 13 is collected, and the soot of the net 13 is dropped and collected to easily obtain C ₆₀ .

As described above, according to the present invention, the amorphous carbon particles and C ₆₀ can be easily separated and collected in relation to the height from the carbon electrode. As a result, as in the conventional method, an organic solvent is used to remove amorphous carbon particles and C from soot.
_The inefficient and time-consuming work of separating the ₆₀ is unnecessary. And, it becomes possible to collect C ₆₀ very easily and efficiently.

In this embodiment, C ₆₀ was collected in a state where the gas did not flow in and out of the bell jar. However, while introducing the gas from the inert gas storage device, the gas was drawn from the upper lid to remove the gas. While balancing the pulling pumping speed and the gas introduction amount, the inside of the bell jar is about 10
It is also possible to collect C ₆₀ while flowing gas so that the pressure becomes 0 Torr. In this case, more C ₆₀ can be collected at one time.

[0025]

As described above, according to the present invention, carbon solids are heated in an inert gas atmosphere, and C ₆₀ and amorphous carbon particles are separated based on the temperature characteristics of smoke produced thereby. Since it is possible to separate and collect C ₆₀ , it is not necessary to separate C ₆₀ from soot using an organic solvent as in the conventional case. Then, it becomes possible to collect C ₆₀ extremely easily and efficiently, and thus C ₆₀ can be provided at low cost.

[Brief description of drawings]

1 is a schematic illustration of a method for collecting C _{60 according} to the present invention.

FIG. 2 is a schematic vertical sectional view showing an embodiment of an apparatus for collecting C _{60 according} to the present invention.

FIG. 3 is a graph plotting the temperature of smoke emanating from a carbon electrode as a function of height above the carbon electrode in the situation shown in FIG.

[Explanation of symbols]

 1 carbon electrode for arc discharge 2 smoke 3 first net (filter means) 4 second net (collection means)

Claims (6)

[Claims] 1. A temperature range in which molecules of carbon 60 are not crystallized in a convection of smoke generated from the pair of carbon electrodes by disposing a pair of carbon electrodes for arc discharge in an inert gas atmosphere to perform arc discharge. In addition, a filter means is arranged to allow the molecules of the carbon 60 to pass through but to capture the amorphous carbon particles, and the temperature region is downstream of the filter means in the smoke convection and where the molecules of the carbon 60 are crystallized. The carbon 60 is characterized in that a collecting means for adhering the crystals of the carbon 60 is arranged on the carbon 60.
Method for collecting. 2. The filter means is arranged in a region of a temperature of 400 to 500 ° C. in the convection of the smoke, and the collecting means is arranged in a region of a temperature of 300 to 350 ° C. in the convection of the smoke. The method of claim 1, wherein 3. The method according to claim 1, wherein the filter means comprises a net. 4. A vacuum chamber, a pair of arc-discharging carbon electrodes arranged inside the vacuum chamber, an external power source connected to the pair of carbon electrodes, and a carbon electrode inside the vacuum chamber. Filter means arranged above, which allows molecules of carbon 60 to pass through but captures amorphous carbon particles, and collecting means which adheres crystals of carbon 60 arranged above the filter means inside the vacuum chamber. A vacuum pump connected to the vacuum chamber, an inert gas supply unit connected to the vacuum chamber, and a vacuum gauge connected to the vacuum chamber, and the filter unit has an arc discharge. Occasionally, the carbon 60 molecules in the smoke convection generated from the pair of carbon electrodes are arranged in a temperature range where they do not crystallize, and the collecting means is arranged to cover the smoke Apparatus for molecules of carbon 60 to collect carbon 60, characterized in that arranged in the temperature range of crystallization. 4. The device according to claim 3, wherein the filter means comprises a net. 5. The device according to claim 4, wherein the net has a dome shape, and the opening of the dome is arranged so as to face the carbon electrode. 6. The filter means is arranged in a region of a temperature of 400 to 500 ° C. in the convection of the smoke, and the collecting means is 300 to 35 in a temperature of the convection of the smoke.
It is arranged in a region of 0 ° C., which is characterized in that
~ The device according to claim 5.