JPH059013A - Fullerene synthesizing device - Google Patents

Abstract

PURPOSE:To provide the device for easily synthesize fullerene at a high yield. CONSTITUTION:An evaporating carbon rod 1 having a diameter within 1mm and a counter electrode carbon rod 2 having the diameter of >=2 times this diameter are brought into contact with each other. The circumference of the carbon rods 1, 2 is enclosed by a cylinder 20. Two holes facing each other are provided on the cylinder 20. The one of these holes is used as a helium introducing port 4 and the other as a suction port 5a for collecting the formed carbon powder. The suction port is differentially discharged and the carbon powder gathers at the collector 6. The carbon rods 1, 2 are heat under resistance to evaporate the carbon from the carbon rod 1. Since just two holes are bored at the cylinder 20, the smooth flow of the carbon vapor from the introducing port 4 side to the suction port 5a side is generated. More than 85% of the consumed carbon rod 1 is, therefore, collected as the carbon powder in the collector. More than 15% in the recovered carbon powder is the fullerence (C60, C70). Since the diameter of the evaporating carbon rod 1 is confined to <=1mm, there is no need for a large-capacity power source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for synthesizing fullerene, which is a soccer ball-shaped cluster molecule consisting of carbon only.

[0002]

2. Description of the Related Art In 1985, the existence of soccer ball-shaped cluster molecules C ₆₀ / C ₇₀ (fullerene) made of carbon was first confirmed by Kuroto. However, until recently, it was not possible to synthesize and isolate fullerenes in large quantities. However, in 1990, fullerene has been able to be isolated and synthesized since a synthetic technique was reported by researchers such as Smalley. As a result of this isolation and synthesis technology, fullerenes have been discovered to have characteristics such as semiconductors and superconductors, and are expected to be applied in the future.

[0003]

The synthesis apparatus first reported by Smolley et al. Uses a carbon rod having a diameter of 6 mm and a helium electrode while water-cooling the periphery of the carbon rod through a current of 100-150 A at 10-20V. It was synthesized under the arc discharge conditions. The yield of fullerenes present in the powder solids produced is reported to be about 10%. (Journal of Physical Chemistry)
However, this method requires a large-capacity power source, and it is necessary to add a function for cooling in order to prevent the device from overheating due to generated heat. In addition, the various clusters formed were scattered throughout the device, so there was a lot of loss in collecting them, and at most about 40% of the vaporized carbon rods could be collected. In other words, the fullerene finally obtained is 4% (0.4 × 0.1 =) of the evaporated carbon rod.
0.04) It was just a matter of time.

The present invention was born from such a situation, and an apparatus for synthesizing fullerenes easily and in high yield without requiring a large-capacity power source and a cooling function such as water cooling is provided. It was made to provide.

[0005]

[MEANS FOR SOLVING THE PROBLEMS] An evaporated carbon rod having an inside diameter of 1 mm and a carbon counter electrode having a diameter more than twice that of the evaporated carbon rod come into contact with each other, and a cover surrounding at least this contact portion is provided. This cover is provided with two holes, one hole is used as a helium inlet, the other hole is differentially exhausted to serve as a suction port for collecting the generated carbon powder, and the carbon rod is resistant in a helium atmosphere. A fullerene synthesizing apparatus characterized by synthesizing fullerene by heating.

[0006]

[Function] As a result of studying carbon rods of various sizes, the size of the carbon rod that evaporates by resistance heating is 1 m in diameter.
In the case of m or less, it was found that a power source of about 10 volts and 40 amps is sufficient, and since the area of the carbon rod to be evaporated is small, the temperature of the entire apparatus does not rise so much and it is not necessary to add a cooling function. It is said that the temperature of the actual evaporating portion of the carbon rod is about 4000 ° C. Further, the carbon rod serving as the counter electrode needs to be twice as large as the carbon rod to be evaporated. This is because when the size of the carbon rod of the counter electrode is small, the counter electrode itself evaporates, and the carbon rod to be continuously vaporized cannot be consumed. In addition, in order to collect the generated fullerene while suppressing it as much as possible, the absorption opening opened in the cylinder surrounding the carbon evaporation source was differentially exhausted to form a collector. With this differentially evacuated collector, 85% or more of the actually consumed carbon rods could be easily recovered in the form of carbon powder. This is 2 for the cover
It is considered that this is because only one hole is opened and the flow of carbon vapor smoothly occurs on the collector side, which is differentially exhausted from the helium introduction side. The amount of fullerene contained in the carbon powder collected in the collector part largely depends on the voltage / current characteristics used and the pressure of helium in the chamber. Under the best conditions, a high yield of 15% or more is obtained. Yes, and was superior to previous reports. The cause of high yield is
This is because high-pressure helium constantly flows into the carbon evaporation portion.

[0007]

1 is a schematic view showing an example of the apparatus of the present invention. The tip of the evaporated carbon rod 1 having a thickness of 0.95 mm and a length of 70 mm is sharpened into a needle shape, and the tip has a thickness of 2 mm and a length of 1.
mm counter electrode carbon rod 2 is contacted. The degree of contact is the degree of contact between the two. The circumference of the carbon rods 1 and 2 is covered with a stainless cylinder 20 having a diameter of 25 mm and a length of 120 mm. Since the cylinder 20 is long, the carbon rods 1 and 2 are entirely covered. The central axes of the carbon rods 1 and 2 and the cylinder 20 are made to coincide with each other. The cylinder 20 has two holes facing each other.
And a suction port 5a for collecting the produced carbon powder. The line connecting the centers of the inlet 4 and the suction port 5a is set to pass through the contact points of the carbon rods 1 and 2. The tip of the helium introduction nozzle 3 is located at the introduction port 4, and the suction port 5a
A suction port 5b on the collector side is installed in the shape of a funnel in the vicinity of, and a cylindrical collector 6 is provided near the suction port 5b. The collector 6 has a water-cooling pipe 7 wound around the outer solid, and cools it by flowing water during fullerene synthesis. First, the chamber was set to 10 ⁻³ torr with the rotary pump 10. After that, helium is introduced from the helium introducing nozzle 3 and the variable leak valve 9 is adjusted to adjust the pressure in the chamber to 1
It was set to 00 torr. In this state, the carbon rod is degassed from the power source 11 with electric power of 3 volts and 10 amps. The vaporized carbon rod 1 was then heated at 10 volts and 40 amps to vaporize the carbon. The carbon vapor is collected in the collector 6 which is differentially pumped and cooled. As a result of collecting the carbon powder in the collector 6 and measuring the yield, it was found that 85% or more of the evaporated carbon rods could be recovered as carbon powder. When the obtained carbon powder was extracted with benzene using a Soxhlet, the yield of fullerene in the carbon powder was 15% or more. Mass spectrometric analysis confirmed that the fullerene was 720 (12 × 6).
0) and 840 (12 × 70) in mass number, and it was confirmed to be C ₆₀ and C ₇₀ , respectively. In addition, as a generation ratio, C ₆₀ was overwhelmingly larger than C ₇₀ . In addition, the temperature rise of the chamber 30 during the experiment is 7
It was not necessary to provide a cooling function such as water cooling below 0 ° C.

[0008]

As described above, by using the apparatus of the present invention, it is possible to obtain a sample in an amount required for a fullerene experiment conducted in a laboratory in a high yield without using a large-scale apparatus. .. In the above-mentioned Examples, the fullerene finally obtained was 13% (0.85 × 0.15) at the worst, which is far higher than the maximum of 4% in the conventional example. Fullerene is a new substance that shows superconducting properties and is expected to be industrially applied in future research and development. By using this device, fullerene can be easily synthesized in high yield, which is significant.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an apparatus of the present invention.

[Explanation of symbols]

 1 carbon rod for evaporation 2 carbon rod for counter electrode 3 helium introduction nozzle 4 introduction port 5a, 5b suction port 6 collector 7 water cooling pipe 8 differential exhaust 9 variable leak valve 10 rotary pump 11 power supply (AC / DC) 20 cylinder 30 chamber

Claims (1)

Claim: What is claimed is: 1. An evaporated carbon rod having a diameter of 1 mm and a carbon counter electrode having a diameter twice or more that of the evaporated carbon rod are in contact with each other, and at least this contact portion is incorporated. A cover is provided, two holes are provided in this cover, one hole is used as a helium inlet port, and the other hole is differentially exhausted to serve as a suction port for collecting the generated carbon powder. A fullerene synthesizing device, which synthesizes fullerene by resistance heating.