JP2586807B2 - Method for producing fullerene intercalation compound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an intercalation compound of fullerene and another element.

[0002]

2. Description of the Related Art C ₆₀ is a new substance in which 60 carbon atoms are gathered in the form of a soccer ball, and was discovered in 1985 by Kroto et al. In addition, mass production of this substance was discovered by Kretschmer et al. In 1990, and its practical application is expected. The series of C _n substances set is similar new 60 C ₇₀ and more carbon atoms carbon carbon atoms other than C ₆₀ was set was set 70 in the form of carbon have been found. These new substances are collectively called fullerenes.

[0003] Fullerene solids are generally semiconductors. Among them, _C60 substances are expected to have various physical properties due to their symmetry. For example, application to light-emitting elements utilizing the photoelectric effect of this material and application to printer photoconductors, conductors or superconductors using intercalation compounds with alkali metals or alkaline earth metals will be the next generation It has many possibilities as a new material. Further, fullerenes have a size in the nm range, and are expected to have new applications utilizing phenomena such as light confinement or electron confinement in the quantization region or mesotropic region as compared with conventional materials.

[0004]

The [invention is a problem to be solved this way, but fullerene, including the C ₆₀ has been attracting attention as an attractive full of new material, because the fullerene itself is basically is a cluster molecule having a closed shell electronic structure, In order to make electronic properties or magnetic properties appear, it is necessary to introduce electrons or holes as carriers into fullerenes by utilizing intercalation with other elements. For such a purpose, a method of mixing fullerene and a material containing another element and then performing thermal diffusion has been used as a method for producing an intercalation compound. However, in such a method, an intercalation compound with an alkali metal or an alkaline earth metal can be formed, but an intercalation compound with another element cannot be formed at present. In addition, even in the case of an intercalation compound with an alkali metal or an alkaline earth metal, it is difficult to form a desired crystal phase because many crystal phases are formed during synthesis.

An object of the present invention is to provide a production method capable of easily synthesizing an intercalation compound of fullerene and another element.

[0006]

According to a first aspect of the present invention, there is provided a method for producing a fullerene intercalation compound, wherein a fullerene (C ₆₀ or C ₇₀ ) and an intercalation material are separately placed in a cell provided in a vacuum chamber. After being charged, the mixture is evaporated while controlling the amount of flux in a vacuum, and is vapor-deposited on a reaction substrate provided opposite to the cell or introduced into a reaction container and mixed, and the reaction substrate or the reaction container is heated. It is characterized by the following.

A method for producing a fullerene intercalation compound according to a second aspect of the present invention is a method for producing a fullerene (C ₆₀ or C ₇₀ ) and an intercalation material separately in a cell provided in a vacuum chamber, Evaporate while controlling the amount of flux, deposit on a reaction substrate provided opposite to the cell, or introduce into a reaction vessel and mix, and heat the reaction substrate or the reaction vessel in an inert gas atmosphere. It is characterized by the following.

[0008]

The crystal system of the host crystal of fullerene solid is determined by its shape. For example, C ₆₀ crystal shows a crystal system called face-centered cubic. The distance between the fullerene cluster molecules in the crystal, that is, the size of the lattice gap, is determined by each crystal system. Therefore, an intercalation compound with an element having an element radius larger than the lattice gap of the original crystal system cannot be produced in principle. In fact intercalation compound of an element and the C ₆₀ such as silicon or tin is difficult to make a very, it is no exaggeration to say that it can not almost.
Furthermore, even when picking up group 4a to group 7a elements or group 4 group 8 elements in the fourth period, these metals have d-electrons and are therefore very interesting candidates for intercalation compounds from the viewpoint of magnetic material. However, conventional methods require extremely high heat treatments, and these elements often form carbide compounds with carbon, so that C ₆₀ intercalation compounds have not been possible to date. In addition, even in combination with an element that forms an intercalation compound, several types of crystal phases including various compositions may be mixed. For example, in the case of K ₃ C _60, an intercalation compound of potassium and C ₆₀ , which is known as a metal, K ₄ C ₆₀ in a body-centered tetragonal form, which is a crystal phase having a different composition, and K ₄ C _{60 in} a conventional manufacturing method Due to the simultaneous co-mingling of the K ₆ C _{60 in the} centered cubic form, the synthesis had to be given a great deal of attention.

[0009] inventors have the result of various studies with respect to such a problem, each separately fullerene C ₆₀ or C ₇₀ to intercalation other elements and substrate to Deployment or reaction vessel Ryoron It has been found that fullerene and intercalation compounds of various elements can be produced by introducing and mixing in a gaseous state and then applying heat to produce intercalation. For example, C ₆₀ and intercalation conventional method with silicon, i.e. C ₆₀ and in the method of the silicon mixed with heat-treated in an inert gas atmosphere or ^10-6
Although the intercalation compound could not be synthesized by the heat treatment at 1000 ° C. under the reduced pressure of Torr, it can be synthesized according to the method of the present invention. This is because, in the conventional manner, C ⁶⁰
Silicon atomic radius to the grating gap crystal (0.18
For 9 nm) is large, intercalation compounds are difficult to produce, according to the method of the present invention, C ₆₀ in the gas phase
It is considered that the intercalation compound was formed when the cluster molecule and the silicon element were subjected to collision reaction to form a solid state. The heat treatment temperature is 80
0 ° C and low temperature were good.

Furthermore, for reasons such as formation of carbide according to the method of the present invention, even if the fourth period element generating the intercalation compound of C ₆₀ is inhibited, after so mixing in the gas phase The heat treatment process is extremely low temperature,
It can be lower than the carbide formation temperature. For this reason, it has been found that it is possible to form a metastable phase intercalation compound which can prevent the thermal equilibrium from proceeding to the most stable compound, carbide. Also, potassium and C
In the case of intercalation compounds of ₆₀ also, in order to respectively synthesized by controlling the stoichiometric ratio from different evaporation sources, the amount of potassium relative to the amount of C ₆₀ 3: face-centered by controlling 1 Only the cubic K ₃ C ₆₀ metal phase could be produced stably and at low temperature. This is probably because that can control a much uniformity as compared to the reaction of potassium C ₆₀ and the bulk of the bulk.

Among the elements used for forming the intercalation compound, alkali metals include lithium, sodium, potassium, rubidium and cesium. In this case, since the vapor pressures of these elements are extremely high, it is necessary to return to normal pressure in an inert gas atmosphere once after evaporating and mixing, and then to perform heat treatment at 100 to 400 ° C. At 100 ° C. or lower, the reaction does not proceed, and at 400 ° C. or higher, elimination occurs. Also, as alkaline earth elements,
There are calcium, strontium and barium. In the case of these elements, since the vapor pressure is not so high, it has been found that it is necessary to set the heat treatment at 10 ^{−2 to} 300 Torr in an inert gas and at a high heat treatment temperature of 400 to 1000 ° C. As rare earth elements, lanthanum,
Cerium, samarium, gadolinium, yttrium and the like can be mentioned. When making intercalation with these elements, 700 ° C.
It turned out that it is necessary to heat-treat below . Examples of group 4b elements of the periodic table include silicon, germanium, tin, and lead. Intercalation with these elements has proven to be very effective if the gas phase mixture from the evaporation source is treated simultaneously in the reaction vessel.
Especially silicon Among these were found to be formed in high purity C ₆₀ and intercalation by evaporation mixing method. This seems to be correlated with the fact that C ₆₀ is in a hybrid bonding state of sp ² and sp ³ and that the silicon element easily takes these bonding modes. Fourth period 4a, 5a, 6
The elements a and 7a or the elements of the fourth period group 8 include
Titanium, vanadium, chromium, manganese, iron, cobalt, nickel and the like. Since these elements easily form carbide with carbon, it has been found that the heat treatment temperature needs to be sufficiently lower than the carbide formation temperature for these elements.

Further, copper, zinc, cadmium, either or C ₆₀ intercalation compound using these mixtures of mercury is suitable for evaporation mixing method, it was found that it is better intercalation compound quality . This is because these elements and fullerenes, especially C ₆₀
It is considered that the transfer of the charge occurs very smoothly. In addition, scandium, yttrium,
Alternatively, in the case of lanthanum, it has been found to be very effective to supply the vapor deposition raw materials in the form of these halides and to mix them by evaporation.

The temperature range of the heat treatment varies depending on the type of the element used and the type of the fullerene.
In the range of ° C., a considerably lower temperature than in the past is sufficient. The mixing speed also varies depending on the combination used, but is generally 0.1 to
A deposition rate range of 100 nm / min is preferred. This is because if it is too slow, it is not practical, and if it is too fast, the mixing becomes uneven. In addition, the heat treatment may be performed after or during the mixing, but the mixing is more preferable in order to maintain heat uniformity.

[0014]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a manufacturing apparatus used in an embodiment of the present invention.

In FIG. 1, a reaction vessel 12 or a reaction substrate 13 heated by a heater 11 connected to a heating power supply 14 is provided in a vacuum chamber 10. A plurality of cells (heating resistance cells or cells for electron beam evaporation) 16A to 16A to be heated by the evaporation power supply 17 are provided in the vacuum chamber 10 facing the reaction vessel 12.
16C is provided, and a flux monitor system 18 for controlling the amount of flux is provided between the cell and the reaction vessel. Reference numeral 15 denotes an exhaust system composed of a turbo pump, a rotary pump, and the like, and reference numeral 19 denotes a pressure control system having a variable valve, a pipe for introducing an inert gas such as argon, and the like.

The fullerene used in the examples was 100 Torr.
It was produced by using a carbon rod having a diameter of 10 mm as a negative electrode and a carbon rod having a diameter of 6 mm as a positive electrode in a helium atmosphere of r and discharging at a direct current of 20 V. Was separated and purified hexane / toluene as a developing solvent column of C ₆₀ and C ₇₀ are contained within the experimental after soot and alumina as filler.

[0017] As Example 1, placed in C ₆₀ purified to the heating resistance cell 16A, put lanthanum other cell 16B for electron beam evaporation. And the vacuum chamber 10
Was reduced to 10 ⁻⁷ Torr, and C ₆₀ was reduced to a cell temperature of about 40.
At 0 ° C., lanthanum was introduced into the reaction vessel 12 maintained at 200 ° C. with an acceleration voltage of 4 kV and an emission current of 100 mA so that the ratio of C ₆₀ to lanthanum was a stoichiometric ratio of 1: 3. The product is treated under argon at 10 atm for 50 atmospheres.
Heat treatment was performed at 0 ° C. for 2 days. When the generated compound was measured using X-ray diffraction, a face-centered cubic intercalation compound having a lattice spacing of 1.46 nm was obtained.

[0018] In accordance with conventional methods the same experiment as Comparative Example 1, C ₆₀ and lanthanum the stoichiometric ratio 1: heat-treated for 2 days with mixed was sealed to 1000 ° C. at 3. Take out X-
It was line analysis, C ₆₀ and lanthanum remained phase separation does not form intercalation.

As Example 2, an experiment similar to that of Example 1 was performed.
It was carried out with respect to intercalation of the C ₆₀ and the silicon. In this case, put silicon into the heating resistance cell and
At a temperature of 000 ° C., the stoichiometric ratio of C ₆₀ to silicon is 1: 3
Were mixed by evaporation. The temperature of the reaction vessel is 800
C. was maintained during the experiment. When the obtained compound was measured by X-ray diffraction, an intercalation compound having a face-centered cubic crystal with a lattice radius of 1.45 nm was formed.

As Comparative Example 2, an experiment similar to that of Example 2 was performed by a conventional method. The C ₆₀ and silicon were mixed in sealed quartz tube and allowed to react for 1 week at 900 ° C.. When the resulting product was examined by X-ray analysis, no intercalation compound was formed and phase separation occurred.

Was deposited from the heating resistor cell while mixing at a ratio of 1 to the reaction substrate 13 consisting of MoS _2: [0021] Potassium and C ₆₀ is an alkali metal as a third embodiment 3. The temperature of the substrate was 100 ° C. K ₃ C _{60 Lee} centers intercalation compound corresponding to the lattice constant face-centered cubic structure lattice constant 1.42nm Looking can compounds with reflection high-energy electron diffraction (RHEED) were able.

As Comparative Example 3, an experiment similar to that of Example 3 was performed.
As before, a C ₆₀ thin film was deposited on the substrate 13 to a thickness of 200 nm, and then potassium was deposited at a stoichiometric ratio of 3 to the amount of C ₆₀ and thermally diffused. This is Rhee
Observation d revealed that several types of crystal phases were mixed.

As Example 4, the experiment of Example 3 was carried out by gas phase mixing so that the ratio of karimou to C ₆₀ was 6: 1. As a result, Rheed revealed that an intercalation compound having a single crystal phase of K ₆ C ₆₀ having a body-centered cubic structure was formed singly.

[0024] Using barium as the alkaline earth metal as Example 5, 3 barium and C ₆₀ from the heating resistor cells: were mixed and controlled by one of the stoichiometric ratio in the gas phase reaction substrate 13
Was deposited. Thereafter, a heat treatment was carried out at 300 ° C. in a vacuum chamber 10 at a pressure of 200 Torr in an argon atmosphere. as a result. The fact that an intercalation compound having an A15 structure of 1.13 nm is produced
It was confirmed from the head measurement.

[0025] The C ₆₀ purified as in Example 6 was placed in a heating resistance cell was charged with trichloroacetic yttrium to the other cells for electron beam evaporation. And the vacuum chamber 10
Was reduced to 10 ⁻⁷ Torr, and C ₆₀ was reduced to a cell temperature of about 45.
Reaction vessel 1 in which trichloroyttrium was kept at 200 ° C. at 0 ° C. with an acceleration voltage of 4 kV and an emission current of 20 mA
2 to C ₆₀ and the ratio of yttrium bur 1: was introduced in such a manner that a stoichiometric ratio of 3. When the generated compound was measured using X-ray diffraction, a face-centered cubic intercalation compound having a lattice spacing of 1.49 nm was obtained.

In Experimental Example 7, purified C60 and nickel, which is a transition metal of the fourth period, were placed in separate vapor deposition cells at 10 ₋₆ T.
The mixture was evaporated and mixed at a stoichiometric ratio of 1: 6 at orr.
The temperature of the reaction vessel 12 during the mixing experiment was kept at 200 ° C. Then, the pressure is set to 600 Torr in an argon atmosphere for 8 hours.
Heat treatment was continued at 00 ° C. for 24 hours. When purified compound X- is linear analysis, it was confirmed that it is different from another intercalated crystal phase and crystal structure of C _60.

In the eighth embodiment, the same operation as in the first embodiment
Boron, a group b element, was performed using an electron beam evaporation cell. The temperature of the reaction vessel 12 keeps the C ₆₀ and the stoichiometric ratio of the boron to 1:12 were mixed at the conditions 250 ° C.. Thereafter, the reaction was carried out at 900 ° C. for 24 hours under a normal pressure under an argon atmosphere. X-ray analysis of the resulting compound confirmed that an intercalation compound having a face-centered cubic structure with a lattice constant of 1.43 nm was formed.

As Example 9, the same operation as in Example 1 was performed using zinc in an electron beam evaporation cell. The stoichiometric ratio of C ₆₀ to zinc was kept at 1: 6 and the temperature of the reaction vessel 12 was kept at 200 ° C.
Under the same conditions. Thereafter, the reaction was performed at 500 ° C. for 24 hours under an atmospheric pressure under an argon atmosphere. X-ray analysis of the resulting compound confirmed that an intercalation compound having a face-centered cubic structure with a lattice constant of 1.41 nm was formed.

In the above embodiment, C ₆₀ is used as fullerene.
Although the case of using C has been described, even if C ₇₀ is used, C ₆₀
An intercalation compound could be produced as in the case of Ne or the like may be used as the inert gas in addition to Ar.

[0030]

As described above, according to the present invention, it is possible to produce intercalation compounds of various foreign elements and fullerenes which cannot be obtained by the conventional method.
Such various intercalation compounds are expected to produce various new functional materials having fullerene as a basic structure, and their industrial utility is extremely high.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an apparatus used in an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vacuum chamber 11 Heater 12 Reaction container 13 Reaction substrate 14 Heating power supply 15 Exhaust system 16A-16C cell 17 Deposition power supply 18 Flux monitor system 19 Pressure control system

Claims (9)

(57) [Claims] 1. A fullerene (C ₆₀ or C ₇₀ ) and an intercalation material are separately placed in a cell provided in a vacuum chamber, and then evaporated in a vacuum while controlling the amount of flux to face the cell. A method for producing a fullerene intercalation compound, comprising: depositing on a reaction substrate provided in advance or introducing into a reaction vessel and mixing, and heating the reaction substrate or the reaction vessel. 2. The method for producing a fullerene intercalation compound according to claim 1, wherein the intercalation material is a substance consisting of one element of Group 3b or 4b of the periodic table. 3. The intercalation material is a metal composed of one element of the fourth period group 4a, 5a group, 6a group, 7a group or 8 group of the periodic table. The method for producing a fullerene intercalation compound according to claim 1, wherein the temperature is lower than a temperature at which carbon and carbide are formed. 4. An intercalation material comprising copper, zinc,
2. The method for producing a fullerene intercalation compound according to claim 1, wherein the metal is one of cadmium and mercury or a mixture of these metals. 5. The method for producing a fullerene intercalation compound according to claim 1, wherein the intercalation material is a halide of scandium, yttrium or lanthanum. 6. A fullerene (C ₆₀ or C ₇₀ ) and an intercalation material are separately placed in a cell provided in a vacuum chamber, and then vaporized in a vacuum while controlling the amount of flux to face the cell. A method for producing a fullerene intercalation compound, characterized in that the reaction substrate or the reaction vessel is mixed by being vapor-deposited on a reaction substrate or a reaction vessel provided therein and heated in an inert gas atmosphere. . 7. The fullerene intercalation according to claim 6, wherein the intercalation material is a substance composed of one of the alkali metals, and is heated at 100 to 400 ° C. in an inert gas atmosphere at normal pressure. A method for producing a compound. 8. The intercalation material is a substance composed of one element of alkaline earth, and is 10 ^{−2 to} 3.
400 to 100 in an inert gas atmosphere of 00 Torr
The method for producing a fullerene intercalation compound according to claim 6, which is heated at 0 ° C. 9. The fullerene intercalation according to claim 6, wherein the intercalation material is a substance made of one of rare earth elements, and is heated at least at 700 ° C. or less in an inert gas atmosphere under a pressurized state. A method for producing a compound.