JPH1192124A - Multinuclear fullerene and multinuclear fullerene structural body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize aggregation of macrofullerene in a rather easy process, and to realize multifunction or high performance of macrofullerene. SOLUTION: A plurality of nuclear fullerenes 4a, 4b comprising macrofullerene are surrounded by a common outer shell fullerene 5 to constitute a multinuclear fullerene 6. The multinuclear fullerene 6 is formed at a desired position near the surface of an amorphous carbon substrate 1. The multinuclear fullerene 6 is obtd. by irradiating the amorphous carbon substrate 1 where superfine particles 2 are deposited with high energy beams 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a giant fullerene having a multinuclear structure and a multinuclear fullerene structure having such a multinuclear fullerene.

[0002]

BACKGROUND ART fullerene represented by C ₆₀ is bonded by intermolecular force, a molecule of the soccer ball with high symmetry. All carbon atoms in the molecule are equivalent and covalently bonded to each other, and are very stable crystals. Fullerenes such as C ₆₀ from exhibit metallic mechanical properties such as plastic deformability and work hardening properties, application to various applications is expected as a new carbon-based material. Further, based on the properties of fullerene itself, applications to superconducting materials, semiconductor materials, lubricant materials, biomaterials, nonlinear optical materials, and the like have been studied.

Conventionally, fullerenes such as C ₆₀ is produced by a laser ablation method of irradiating an arc discharge method or an ultraviolet laser in which the carbon rod and the particulate carbonaceous an electrode on the graphite surface. Since fullerene is produced in a mixed state in soot, it is extracted by a filter or a collector using benzene or the like.

[0004] The material deposited on the cathode side during the arc discharge described above contains higher fullerenes (giant fullerenes) called carbon nanocapsules and carbon nanotubes. By purifying using an organic solvent such as ethanol,
The above-described carbon nanocapsules and carbon nanotubes are obtained. Since carbon nanocapsules and carbon nanotubes each have a hollow shape, synthesis of new substances and search for new functions are being carried out by confining other metal atoms, fine crystals, etc. in those hollow parts. .

[0005] Giant fullerenes in which other metal atoms or fine crystals are confined in the hollow portions of carbon nanocapsules or carbon nanotubes (hereinafter referred to as giant included fullerenes) are conventionally known as fine particles of carbides of rare earth metals such as La and Y. And those containing metal fine particles such as Fe, Co, and Ni have been reported. These are obtained by performing arc discharge or the like using a carbon electrode charged with a powder of a metal, an oxide, or the like, and purifying the giant fullerene contained in the cathode deposit.

Further, called fullerenes with larger molecular weight to the shell of a core consisting of a C ₆₀ as a kind of giant fullerene is overlapped concentrically, onion-like fullerenes (Onion-Like fullerene (onion-like graphite)) Substances have also been discovered. Using such onion-like graphite to produce giant endohedral fullerenes is also being studied.

[0007]

The giant fullerenes and the giant fullerenes as described above are based on their own characteristics, and are based on device materials such as electronic element materials, sensor materials, filter materials, superconducting materials, biomaterials, and the like. It is expected to be applied to new functional materials such as medical materials. on the other hand,
When considering the application of giant fullerenes to various devices and new functional materials, it is desirable to have more various functions. Can not. Therefore, there is a demand for further increasing the functionality and performance of giant fullerenes.

[0008] Conventional giant fullerenes and encapsulating giant fullerenes are contained in deposits formed by the arc discharge method as described above, and therefore, separation from impurities such as graphite-like substances and amorphous carbon itself is not possible. Is difficult. In particular, when considering the application of giant fullerenes and encapsulated giant fullerenes to devices and new functional materials, it is important to be able to control the aggregation (eg, film formation) of giant fullerenes. Such control cannot be easily performed by the conventional method for producing giant fullerenes.

SUMMARY OF THE INVENTION The present invention has been made to address such a problem, and realizes the aggregation of giant fullerenes by a relatively simple process, and enables the giant fullerenes to have more functions and higher performance. It is an object of the present invention to provide a multi-nuclear fullerene and a multi-nuclear fullerene structure.

[0010]

According to the present invention, there is provided a multi-nuclear fullerene according to the present invention, wherein a plurality of nuclear fullerenes composed of giant fullerenes and an outer shell fullerene existing so as to surround the plurality of nuclear fullerenes are provided. Are provided.

[0011] The multinuclear fullerene structure of the present invention comprises an amorphous carbon substrate and a multinuclear fullerene formed near the surface of the amorphous carbon substrate. A multinuclear fullerene structure,
The multinuclear fullerene has a structure in which a plurality of nuclear fullerenes composed of giant fullerenes are wrapped in a common outer shell fullerene.

In the multinuclear fullerene and the multinuclear fullerene structure of the present invention, for example, onion-like fullerene is used as a giant fullerene as a nuclear fullerene. In this case, the outer shell fullerene has a structure similar to onion-like fullerene as a core fullerene.

In the present invention, a structure in which a plurality of nuclear fullerenes composed of giant fullerenes are wrapped in a common outer shell fullerene, that is, a giant fullerene having a multinuclear structure is realized. According to such a multinuclear fullerene,
By controlling the properties and characteristics of each giant fullerene as a nuclear fullerene, it is possible to obtain a giant fullerene with multiple functions and higher performance.

Further, the multinuclear fullerene can be regarded as an aggregate of giant fullerenes as nuclear fullerenes. Therefore, for example, by controlling the number of nuclear fullerenes, various aggregates of giant fullerenes can be obtained. This is effective when applying giant fullerenes to devices and new functional materials.

[0015]

Embodiments of the present invention will be described below.

FIG. 1 and FIG. 2 are diagrams schematically showing one embodiment of a production process of a multinuclear fullerene and a multinuclear fullerene structure according to the present invention. In these figures, reference numeral 1 denotes an amorphous carbon substrate serving as a material for forming multinuclear fullerenes. As a constituent material of the amorphous carbon substrate 1, for example, i-carbon or the like is used. The thickness of the amorphous carbon substrate 1 is not particularly limited.
A thin film substrate having a thickness of about 100 nm is preferably used.

On the amorphous carbon substrate 1 as described above, for example, as shown in FIG. 1A, ultrafine particles 2 serving as a nucleation material for generating giant fullerene are arranged. The ultrafine particles 2 are basically installed in accordance with the number of giant fullerenes as nuclear fullerenes described later. However, by moving one ultrafine particle 2 by irradiation with a high energy beam such as an electron beam, In some cases, it functions as a nucleation material for a plurality of nuclear fullerenes.

As the ultrafine particles 2 serving as nucleation substances, ultrafine particles made of various solid materials such as metal ultrafine particles, semiconductor ultrafine particles, and compound ultrafine particles can be used.
In other words, a giant fullerene as a nuclear fullerene can be induced and grown using the ultrafine particles 2 made of various solid substances as a nucleation substance (nucleation point) as described later.

Specific examples of the ultrafine particles 2 include Al, A
Metal ultra-fine particles made of various single metals and alloys such as u, Cu, Pt, Sn, Mo, W, semiconductor ultra-fine particles made of Si, GaAs, etc., metal oxides, metal chlorides, metal fluorides, metal borides And ultrafine particles of various metal compounds. In particular, ultrafine metal particles exhibiting a good catalytic effect in a nuclear fullerene activation step described below are preferably used. When two or more ultrafine particles 2 are arranged, different 2
A plurality of types of ultrafine particles having different materials may be used, such as more than one kind of metal ultrafine particles or a metal ultrafine particle and a compound ultrafine particle.

The size of the ultrafine particles 2 may be any size that can provide a nucleation point when generating a giant fullerene as a nuclear fullerene.
It is preferable to use ultrafine particles 2 of about 00 nm. It is to be noted that the ultrafine particles 2 having a diameter of less than 1 nm are difficult to exist and produce themselves, and may not be able to sufficiently exert the function as a nucleation point of giant fullerene.
The more preferred diameter of the ultrafine particles 2 is in the range of 1 to 40 nm.

The method for producing the ultrafine particles 2 is not particularly limited. If the ultrafine particles 2 can be arranged on the amorphous carbon substrate 1, the ultrafine particles 2 produced by various methods can be used.
Can be used.

For example, a target provided with a plurality of pores or slits is arranged on the amorphous carbon substrate 1, and a high energy beam such as an Ar ion beam is obliquely applied to the inner wall of the pores or the inner wall of the slits of the target. By irradiating from the direction to separate constituent atoms and constituent molecules of the target, ultrafine particles made of the constituent material of the target can be obtained. According to such a method (hereinafter, referred to as a transfer method), the size and arrangement shape of the ultrafine particles can be controlled by the shape of the pores and slits of the target.

Further, the θ-positioned on the amorphous carbon substrate 1
By irradiating a metastable compound particle such as an Al ₂ O ₃ particle with a high energy beam such as an electron beam, α-Al ₂ O ₃ particles as a stable phase and Al ultrafine particles as a constituent metal of Al ₂ O ₃ And so on. This method (hereinafter, referred to as a compound decomposition method) is also effective for W, Mo, Cu, and the like, in which compounds, particularly oxides, are easily decomposed.

Next, as shown in FIG. 1A, a high energy beam 3 is applied to the amorphous carbon substrate 1 on which the ultrafine particles 2 are arranged. The high-energy beam 3 to be irradiated is not particularly limited, and it is sufficient that the high-energy beam 3 has energy capable of activating amorphous carbon existing around the ultrafine particles 2 to induce giant fullerene. For example, if the strength is 1 ×
Examples include an electron beam of 10 ¹⁹ e / cm ² · sec or more, a particle beam such as an ion beam having the same intensity as this electron beam, a photon such as a laser, an X-ray, a γ-ray, and a neutron beam.

When an electron beam is used as the high-energy beam 3, if the irradiation intensity is less than 1 × 10 ¹⁹ e / cm ² · sec, the amorphous carbon around the ultrafine particles 2 is converted into a large fullerene so as to be able to produce huge fullerenes. May not be activated. In other words, an electron beam having an intensity of 1 × 10 ¹⁹ e / cm ² · sec or more brings about an activation effect of the ultrafine particles 2 and the amorphous carbon around the particles, which can generate giant fullerene. Become. The same applies to the case where a particle beam, photon, X-ray, γ-ray, neutron beam or the like is used as the high energy beam 3.

The irradiation atmosphere of the high energy beam 3 may be set according to the beam to be used.
An inert atmosphere such as an argon atmosphere may be used. For example, the atmosphere when applying electron beam irradiation is 1 ×
The vacuum atmosphere is preferably 10 ⁻⁵ Pa or less, which can prevent adsorption of residual gas atoms and the like, thereby promoting the generation of giant fullerene.

The high energy beam 3 as described above is
When the amorphous carbon substrate 1 on which the ultrafine particles 2 are arranged is irradiated, the amorphous carbon in the irradiation region of the high energy beam 3 is activated, and as shown in FIGS. 1 (b) and 2 (a). Then, a plurality of giant fullerenes 4 (4a, 4b) are induced using the ultrafine particles 2 as nucleation substances. The induced giant fullerene 4 is a concentric spherical giant fullerene, that is, onion-like fullerene (onion-like graphite).

In the process of producing the giant fullerene 4, each giant fullerene 4a, 4b is a normal single nucleus onion-like fullerene or the like. These giant fullerenes 4a and 4b serve as core fullerenes of a multinuclear fullerene described later. The ultrafine particles 2 used as the nucleation material are dispersed, for example, in an atomic state in each of the giant fullerenes 4a and 4b and in the amorphous carbon substrate 1 around the huge fullerenes 4a and 4b, and function as a catalyst in a subsequent activation step It is.

Next, a plurality of giant fullerenes 4a and 4b generated near the surface of the amorphous carbon substrate 1 are further irradiated with a high energy beam 3 '. The giant fullerenes 4a and 4b are activated by the irradiation of the high energy beam 3 ', and move so that the adjacent giant fullerenes 4a and 4b are gathered. For the activation of the plurality of giant fullerenes 4a and 4b and the aggregation based on the activation,
The catalytic effect of the ultrafine particles 2 used as the nucleation material also contributes.

The high energy beam 3 'irradiated in the activation step of the giant fullerene 4
In activating a and 4b, it is preferable to use a material having a higher strength than that of the step of producing the giant fullerene 4. When an electron beam is used as the high energy beam 3 ', the intensity is 1
It is preferable to use an electron beam of at least × 10 ²⁰ e / cm ² · sec, an ion beam having the same intensity as this electron beam, a laser, an X-ray, a γ-ray, a neutron beam, or the like. Irradiation intensity 1 × 10
^If it is less than ²⁰ e / cm ² · sec, each huge fullerene 4a,
4b may not be activated enough to move.

By continuously irradiating the high energy beam 3 ', as shown in FIG. 2C, for example, a state in which carbon on the outer shell side of the adjacent giant fullerenes 4a and 4b is obtained. Thus, the activation process of the giant fullerene 4 is preferably performed until the outer shell sides of the adjacent giant fullerenes 4a and 4b are overlapped.
Further, by the activation step of the giant fullerene 4, the number of nuclear fullerenes of the multinuclear fullerene generated in the subsequent outer shell commonization step can be controlled. That is,
Although FIGS. 1 and 2 show a state in which carbon on the outer shell side of the two giant fullerenes 4a and 4b is overlapped, it is also possible to assemble a larger number of giant fullerenes 4.
In this case, a larger number of giant fullerenes 4 are gathered by enlarging the irradiation area of the high energy beam 3 'or irradiating the giant fullerenes 4 individually with the high energy beam 3' and moving each of them individually. be able to.

After the step of activating the giant fullerene 4 as described above, as shown in FIG. 1D, the high energy beam 3 having the same intensity as that of the step of generating the giant fullerene 4 is further irradiated. . By the irradiation of the high energy beam 3, as shown in FIGS. 1D and 2D, the carbon atoms on the outer shell side of the adjacent giant fullerenes 4a and 4b are partially shared, and A multi-layer fullerene shell (outer shell fullerene) 5 is induced so as to enclose these giant fullerenes 4a and 4b on the outside.

At this time, since each of the giant fullerenes 4a and 4b almost maintains the original shape except for a part of the carbon on the outer shell side, each of the giant fullerenes 4a and 4b becomes the outer fullerene 5
Inside each other as nuclear fullerenes.
The outer shell fullerene 5 has a structure similar to the core fullerene. For example, when the core fullerene is onion-like fullerene, the outer shell fullerene 5 has a similar crystal structure.

That is, as shown in FIGS. 1D and 2D, a multinuclear fullerene 6 having a structure in which a plurality of nuclear fullerenes composed of giant fullerenes 4a and 4b are wrapped by a common outer shell fullerene 5. Is obtained. In other words, a multi-nuclear fullerene 6 including a plurality of nuclear fullerenes composed of the giant fullerenes 4a and 4b and an outer shell fullerene 5 that surrounds the plurality of nuclear fullerenes 4a and 4b is obtained. Such multi-nuclear fullerenes 6 are formed in the vicinity of the surface of the amorphous carbon substrate 1, thereby forming a multi-nuclear fullerene structure 7.

As described above, the high energy beam 3 '
Giant fullerenes 4a, 4a activated by irradiation
By irradiating b with the high-energy beam 3 at the same time, the multinuclear fullerene 6 and the multinuclear fullerene structure 7 can be obtained. The size of the obtained multinuclear fullerene 6 and the number of nuclear fullerenes can be controlled by the irradiation area, intensity, irradiation time of the high energy beam 3 ′, and the initial number of giant fullerenes 4. Furthermore, the giant fullerene 4 as a nuclear fullerene can be made into a giant fullerene containing ultrafine particles by controlling the intensity and irradiation time of the high energy beam 3 at the time of generation.

Further, as shown in FIG.
Is used as a nucleation point to induce and grow a giant fullerene 4a as a nuclear fullerene (FIG. 3A), and then the ultrafine particles 2 are moved by irradiation with a high energy beam such as an electron beam (FIG. 3B). At the point where the ultrafine particles 2 move, a giant fullerene 4b as a nuclear fullerene can be further induced and grown (FIG. 3C). By irradiating such a plurality of giant fullerenes 4a and 4b with an even higher energy beam, FIG.
As shown in (d), a multinuclear fullerene 6 having a structure in which a plurality of nuclear fullerenes composed of giant fullerenes 4a and 4b are wrapped by a common outer shell fullerene 5 is obtained.

The multi-nuclear fullerene 6 can be regarded as an aggregate of giant fullerenes 4a and 4b as nuclear fullerenes. Therefore, by controlling the properties and characteristics of each of the nuclear fullerenes 4a and 4b, multi-functional fullerenes 6 can be obtained. Giant fullerenes with improved performance can be obtained. For example, when the nuclear fullerene is an ultrafine particle-encapsulated giant fullerene, a giant fullerene obtained by combining (aggregating) a plurality of functions can be obtained by differentiating the encapsulated particles of each nuclear fullerene.

Further, by controlling the activation step as described above, it is possible to obtain multinuclear fullerenes 6 in which the number of nuclear fullerenes is controlled, that is, aggregates of various forms of giant fullerenes. For example, a film having a certain area can be formed by wrapping a large number of giant fullerenes with a common outer shell fullerene. These are effective when giant fullerenes are applied to devices and new functional materials.

When the high energy beams 3 and 3 'are irradiated, the amorphous carbon substrate 1 may be kept at room temperature, and the multinuclear fullerene 6 may be formed on a controllable room temperature stage. it can.

The multi-nuclear fullerene structure 7 as described above is obtained by converting the multi-nuclear fullerene 6 to the amorphous carbon substrate 1.
Since it can be formed at an arbitrary position, it is extremely effective in developing applications utilizing the properties of giant fullerenes including giant fullerenes containing ultrafine particles. That is, by using the multinuclear fullerene structure 7, it is possible to realize various operations and controls of giant fullerenes (giant fullerenes enclosing ultrafine particles), various application developments, and the like.

In the present invention, the size of the multinuclear fullerene 6 to be obtained depends on the irradiation time, irradiation intensity, irradiation atmosphere, size, number, and type of the giant fullerene 4 initially. Since the properties, shape, formation position, and number of nuclear fullerenes can be controlled, the applicable range is extremely wide. For example, the multi-nuclear fullerene structure 7 described above uses the characteristics of the multi-nuclear fullerene 6 or the individual characteristics of the nuclear fullerene to make use of device materials such as electronic element materials, sensor materials, and filter materials, and superconducting materials. It can be applied to new functional materials such as biomaterials and medical materials.

[0042]

Next, specific examples of the present invention will be described.

Example First, a plurality of ultrafine Al particles having a diameter of 10 to 35 nm were arranged on a 20-nm-thick amorphous carbon support film (amorphous carbon substrate) made of i-carbon. The Al ultrafine particles are formed by a compound decomposition method. This was set on a room temperature stage in a vacuum chamber of a 200 kV TEM device (JEM-2010 (trade name) manufactured by JEOL Ltd.).

Next, 1 × 10 ⁻⁵ Pa in a vacuum atmosphere of 1 × 10 ⁻⁵ Pa
An electron beam having an intensity of ²⁰ e / cm ² · sec was irradiated on the amorphous carbon support film on which a plurality of Al ultrafine particles were arranged. The irradiation time of the electron beam was 2400 seconds. After the electron beam irradiation, the state of the amorphous carbon support film was observed with a TEM.
It was confirmed that fullerene nuclei were induced from the underlying amorphous carbon in accordance with the ultrafine particles, and a plurality of concentric spherical fullerenes having a multilayer structure, that is, onion-like fullerenes, were generated. These initial onion-like fullerenes had a single nucleus.

Of the plurality of onion-like fullerenes thus produced, two adjacent onion-like fullerenes were irradiated with an electron beam having an intensity of 3.3 × 10 ²⁰ e / cm ² · sec. As a result, it was confirmed that the two onion-like fullerenes approached, and that the carbon on the outer shell side was overlapped. The irradiation time of the electron beam was 2400 seconds.

With respect to the two onion-like fullerenes activated in this way, 1 × 10 ²⁰ e / cm ² · sec
Is irradiated for 600 seconds, and TE
M observation was performed. As a result, the carbon atoms on the outer shell side of the two onion-like fullerenes are partially shared, and a multi-layer fullerene shell (outer shell fullerene) is induced to further wrap these two onion-like fullerenes. It was confirmed that. The two onion-like fullerenes on the inside maintained that state.

The two onion-like fullerenes were present so as to be enveloped by a common shell fullerene. That is, it was confirmed by TEM observation that a multinuclear fullerene having a structure in which a plurality of nuclear fullerenes composed of two onion-like fullerenes were wrapped by a common outer shell fullerene was obtained. Such multinuclear fullerenes existed in the vicinity of the surface of the amorphous carbon support film, and constituted a multinuclear fullerene structure.

[0048] In the above embodiment, as the ultrafine particles disposed on the amorphous carbon support film, using Au ultrafine particles in place of the Al ultrafine particles, Pt ultra-fine particles, Al ₂ O ₃ ultrafine particles, etc., respectively, Irradiation with an electron beam under the same conditions yielded a similar multinuclear fullerene.

On the other hand, as a comparative example with the present invention, when an amorphous carbon support film on which no ultrafine particles such as Al ultrafine particles were arranged was irradiated with an electron beam under the same conditions as in the above example,
No multinuclear fullerene was produced.

[0050]

As described above, according to the present invention, it is possible to obtain, for example, a multinuclear fullerene capable of imparting new functions and characteristics, and a composite of the multinuclear fullerene and an amorphous carbon substrate. Therefore, such multinuclear fullerenes and composites thereof according to the present invention greatly contribute to application development of giant fullerenes and the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a manufacturing process of a multinuclear fullerene and a multinuclear fullerene structure according to one embodiment of the present invention.

FIG. 2 is a plan view schematically showing a main part of a process of manufacturing a multinuclear fullerene and a multinuclear fullerene structure according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view schematically showing a process for manufacturing a multinuclear fullerene and a multinuclear fullerene structure according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Amorphous carbon substrate 2 ... Ultrafine particle 3 ... High energy beam 4 ... Giant fullerene (nuclear fullerene) 5 ... Shell fullerene 6 ... Multinuclear fullerene 7 ... Multinuclear fullerene structure

Claims (4)

[Claims] 1. A multi-nuclear fullerene comprising: a plurality of nuclear fullerenes composed of giant fullerenes; and an outer shell fullerene that surrounds the plurality of nuclear fullerenes. 2. The multinuclear fullerene according to claim 1, wherein the giant fullerene is an onion-like fullerene. 3. A multi-nuclear fullerene structure comprising an amorphous carbon substrate and a multi-nuclear fullerene formed near a surface of the amorphous carbon substrate, wherein the multi-nuclear fullerene is a giant fullerene. A multi-nuclear fullerene structure, characterized by having a structure in which a plurality of nuclear fullerenes are wrapped with a common outer shell fullerene. 4. The multinuclear fullerene structure according to claim 3, wherein the giant fullerene is an onion-like fullerene.