JPH06321686A - New production of carbon cluster compound doped with metal atom - Google Patents

Abstract

PURPOSE:To enable high-quality massproduction and to improve productivity by mixing org. solvent soln. respectively dissolving salt of metal org. acid and carbon cluster under stirring in an inert gas flow or under irradiation with ultrasonic waves. CONSTITUTION:A soln. (A) as a metal ion supply is prepared by dissolving a salt of metal org. acid in a polar org. solvent. A soln. (B) is prepared by dissolving carbon cluster in a same solvent as used for the soln. (A) or in an aromatic nonpolar solvent. These solns. are mixed and vigorously stirred in an inert gas flow for several ten min or several ten hours at room temp. or lower, or vigorously stirred under irradiation with ultrasonic waves for several min to several hours to precipitate a fine single crystal. Or, the two solns. (A) and (B) are brought into contact with each other and maintained in a contact state for one to several ten days to diffuse in order to precipitate a single crystal in the interface. Or, salt of metal org. acid and carbon cluster are dissolved in an org. solvent and subjected to electrolytic crystal growing by using platinum or metal electrodes to grow a single crystal on the cathode. Thus, a carbon cluster compd. doped with metal atoms is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention shows a semiconductor property, a conduction property, or a superconducting property, and is therefore expected to be applied and used particularly in the electronics field. Wet chemistry of a carbon cluster compound doped with a metal atom. The present invention relates to a new manufacturing method by a physical method.

2. Description of the Related Art The carbon cluster compound represented by C ₆₀ , whose existence was first revealed in 1985, is 1
Since the discovery of a large-scale synthetic manufacturing method by the arc discharge method in 990, research in the physical and chemical fields has made explosive progress. In particular, those doped with an alkali metal or an alkaline earth metal exhibit conductivity or superconductivity, and are therefore of great interest in terms of physical properties. In the future, electronic materials will be used as new semiconductor materials, conductive materials, or superconducting materials. Applications in fields are also expected. However, this production method has hitherto been a chemical vapor deposition method (CV) in which an alkali metal or an alkaline earth metal is vaporized at a high temperature under a high vacuum, and the vaporized carbon clusters are condensed on a substrate.
D) and the ion cluster beam method (ICB), the morphology of the obtained substance was limited to a fine solid or thin film material. In addition, this substance is extremely sensitive to air, and it is extremely difficult to accurately control the composition by this production method, so that physical property control is an extremely difficult subject. Although the thin film forming technique is advancing day by day due to improvement in vacuum technique and device technique, it is not suitable for general industrialization because an expensive vacuum device is used, and a breakthrough of the technique is required. Recently, single crystal C ₆₀ has been obtained by the Vapour-Transport method, so that superconducting materials other than thin film materials can be obtained as a bulk by doping alkali metal vapor into it. Further, a method using an azide compound (for example, NaN ₃ or the like) as an alkali metal source has become popular. However, in order to obtain a compositionally uniform material, a remarkably complicated procedure such as repeating the operations of doping and annealing is required, and it is very difficult to obtain reproducible results.

[0002]

Problems to be Solved by the Invention Alkali metal and alkaline earth metal-doped carbon cluster compounds, which are expected as novel semiconductors and superconductors, are not suitable for delicate control of the crystal structure in order to exhibit physical properties. Strict processing is required. However, in reality, the manufacturing process of the substance has many problems including delicate control of the vacuum apparatus and high purity of the raw material. Further, as described above, in the manufacturing method by the dry process, since the control of the manufacturing apparatus such as the CVD apparatus is delicate, many voids and cracks are easily generated on the surface of the thin film, and it is technically difficult to manufacture a good quality thin film. There are quite difficult factors in. Other thin film manufacturing methods include sputtering and ion cluster beam methods, but these methods require special equipment that generates high vacuum and high voltage, and materials that are difficult to vaporize There was a problem that it was difficult to handle. Further, even if single crystal C ₆₀ is used, the process of doping an alkali metal or an alkaline earth metal is a dry process, so there is no guarantee that the product is a high-quality single crystal substance. The inhomogeneity of the inevitable. An attempt to produce the substance by the solution method has been conducted by K _x C ₆₀ [Inorg.
m., 30 , 2838 (1991)], Rb _x C ₆₀ [Inorg.Chem., 30 ,
2962 (1991)], but the reaction proceeds in a heterogeneous system due to the use of metal potassium or metal rubidium, and unreacted metal potassium or metal rubidium is mixed in the product. There is a disadvantage that it is not pure. Actually, the superconducting phase is only 1 to 3%, and it is unlikely that a single crystal can be obtained by this method.

[0003]

[Means for Solving the Problems] As a result of intensive studies conducted by the present inventors to solve the above problems, a method for producing a carbon cluster compound doped with metal atoms by a wet chemical single crystal growth method. The present invention has been completed and the present invention has been completed. That is, according to the present invention, the metal organic acid salt and the carbon cluster are respectively dissolved in a soluble organic solvent, and the two liquids are combined and vigorously stirred and mixed under an inert gas stream, or vigorously mixed by ultrasonic irradiation. It is an invention of a method for producing a carbon cluster compound doped with a metal atom (hereinafter abbreviated as a mixing method), which comprises depositing a fine single crystal of the compound. Further, according to the present invention, a metal organic acid salt and a carbon cluster are each dissolved in a soluble organic solvent, and the two liquids are allowed to stand still to diffuse to precipitate a single crystal of the compound from the two liquid interface. This is an invention of a method for producing a carbon cluster compound doped with a metal atom (hereinafter abbreviated as a diffusion method), which is characterized in that Further, the present invention is characterized in that a single crystal of the compound is grown on the cathode side by an electrolytic crystal growth method in an organic solvent in which a metal organic acid salt and a carbon cluster are dissolved, the carbon cluster doped with a metal atom. It is an invention of a method for producing a compound (hereinafter abbreviated as an electrolysis method).

Examples of the metal organic acid salt used in the present invention include carboxylates such as formates and acetates of various metals, metal acetylacetonato salts, metal tetrakis (acetonitrile) salts, metal tetraphenylborate salts, etc. Examples thereof include salts soluble in polar organic solvents, and among them, metal tetraphenyl borate is particularly preferably used. Among the metal tetraphenyl borate salts, there are commercially available sodium salts, which may be used as they are. In the case of other metal salts, for example, commercially available sodium tetraphenylborate (NaB (C ₆ H ₅ ) ₄ ) is reacted with an excess amount of a desired metal halide by a cation exchange reaction using water as a solvent. The obtained metal tetraphenylborate salt crystals can be easily obtained by filtering, drying, etc., and thus it is sufficient to use the thus obtained crystals. Metal atoms that can be doped with carbon clusters by the method of the present invention include 1A group (alkali) metals (Li, N).
a, K, Rb, Cs, Fr), 2A genus (alkaline earth)
Metals (Be, Mg, Ca, Sr, Ba, Ra), 3B group transition metals (Sc, Y), lanthanoids (La, Ce,
Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, H
o, Er, Tm, Yb, Lu), actinoid genus (A
c, Th, Pa, U, Np, Pu, Am, Cm, Bk,
Cf, Es, Fm, Md, No, Lr), Group 4B transition metal (Ti, Zr, Hf), Group 5B transition metal (V, Nb,
Ta), 6B group transition metals (Cr, Mo, W), 7B group transition metals (Mn, Tc, Re), 8B group transition metals (Fe,
Co, Ni, Ru, Rh, Pd, Os, Ir, Pt),
1B group transition metal (Cu, Ag, Au), 2B group transition metal (Zn, Cd, Hg), 3A group typical metal (Al, Ga,
In, Tl), 4A group typical metal (Ge, Sn, Pb),
5A group typical metal (Sb, Bi), 6A group typical metal (P
o) etc. are mentioned. In addition, B, Si, which is highly non-metallic,
According to the method of the present invention, it is possible to use P, As, Se, Te and the like as doped atoms.

The carbon cluster used in the present invention includes a series of fullerene compounds such as C ₆₀ and C ₇₀ . Since these are commercially available products, they may be used as they are or, if necessary, purified by column chromatography or the like before use. The organic solvent in which the metal organic acid salt is dissolved varies depending on the characteristics of the metal organic acid salt, but is preferably a polar organic solvent such as tetrahydrofuran (THF) alone or a mixed solvent thereof with another organic solvent. Used. The organic solvent that dissolves the carbon clusters may be any solvent that can dissolve the carbon clusters used. For example, an aromatic nonpolar solvent, particularly chlorobenzene or the like, alone or with other organic solvents. Usually, it is preferably used in the form of a mixed solvent. The organic solvent in which the metal organic acid salt is dissolved and the organic solvent in which the carbon clusters are dissolved may be the same kind or different kinds. Examples of the inert gas used in the mixing method of the present invention include nitrogen gas and argon gas.
The temperature during stirring and mixing or ultrasonic irradiation and mixing is usually room temperature, but cooling or the like is optional if necessary. The reaction time varies depending on the scale of the reaction and the like and is not constant, but in the case of stirring and mixing, it is usually several tens of minutes to several tens hours, and
In the case of ultrasonic irradiation, it is usually several minutes to several hours. still,
The stirring and mixing is generally performed by stirring with a stirrer under an inert gas flow, but bubbling stirring with an inert gas may be used instead of the stirrer.

In the diffusion method of the present invention, the standing time required for depositing a single crystal varies depending on the compound, but it usually takes 1 to several tens of days. The electrolysis method of the present invention is a constant current electrolysis,
Any of the constant voltage electrolysis can achieve its purpose. The preferred current density during the electrolysis reaction varies depending on the kind of the metal organic acid salt to be used and the kind of the carbon cluster to be combined, and therefore may be appropriately selected according to the target compound. Usually, a platinum electrode or a so-called metal electrode in which a noble metal such as platinum or ruthenium oxide or its oxide is plated or coated on titanium is preferably used on both the cathode side and the anode side.

[0007]

The basic reaction of the present invention is to use various metal organic acid salts soluble in an organic solvent as a metal ion source and to chemically react carbon clusters having a strong electron affinity by the oxidation reaction accompanying the formation of these metal ions. The single crystal of a carbon cluster compound doped with a homogeneous and high-quality metal ion is wet-chemically grown by reducing it to. The size of the single crystal of the metal-doped carbon cluster compound produced is in the order of mixing method <diffusion method <electrolysis method. In the liquid phase homogeneous system, the redox reaction between the molecules occurs very rapidly in the three-dimensional reaction field, so that the homogeneity of the product is extremely high.

EXAMPLES Examples will be shown below, but the present invention is not limited to these examples.

Example 1 Using a diffusion cell made of H-type glass under a nitrogen gas atmosphere, 50 mg of commercially available sodium tetraphenylborate was added to THF.
It was dissolved in 13 ml, and a chlorobenzene solution (26 ml) containing 10 mg of C ₆₀ was gently added dropwise. A few days later, a black needle-shaped single crystal started to grow from the mixed interface of the two liquids, and in about one month, the purple color of the solution completely disappeared and turned into a yellow solution. From this, it was found that the reaction proceeded almost quantitatively. The grown needle crystals were collected by filtration, washed with n-hexane and dried. The material was microscopically observed to be a fine single crystal. (Yield 88%). The results of elemental analysis are shown below. Elemental analysis value (Na _x C ₆₀ ) Actual value (%) C: 85.81 H: 0.97 N: 0 Calculated value (%) x = 1 C: 96.91 x = 3 C: 91.26 x = It is known that 6 C: 83.93 Na _x C ₆₀ has x of 1,3,6.
From the measured C%, it seems that x = 6 is closer,
C is always low in fullerenes (soot does not burn), so it was thought that x = 3, but ¹ H, ¹³ C
From the solid-state NMR measurement result, it was revealed that THF was present as a crystal solvent, and the composition was Na _x C.
It was found to be expressed in the form of ₆₀ (THF) y (0 <x ≦ 0.5, 0 <y ≦ 3). ESR spectrum (apparatus: JEO
L-FE1X, conditions: microwave power 50 mW, modulation 2G) in FIG. 1 and SEM photograph in FIG.
And an IR chart are shown in FIG. 3, respectively. The g value of the ESR spectrum signal is g = 1.999, and the line width is about 35.
It was G. This suggests the presence of C ₆₀ anion radicals. [Matched with the values of J.Am.Chem.Soc., 113 , 2780 (1991) and J.Am.Chem.Soc., 115 , 1185 (1993)] Also, measurement of conductivity (by DC 4-terminal method) As a result of performing a single crystal sample, it was found that it was a metal or a semiconductor from room temperature to around 100 K, and had a metal-metal transition near 170 K, and the conductivity was further improved by one digit or more. (FIG. 4) A photograph of crystal growth of Na _x C ₆₀ (THF) y in this example is shown in FIG.

Example 2 Under a nitrogen gas atmosphere, 30 mg of commercially available sodium tetraphenylborate was dissolved in 5 ml of THF, mixed with 5 mg of C ₆₀ in chlorobenzene (10 ml) and bubbled with nitrogen gas for about 20 minutes. Formation of a black suspension was observed inside. This was collected by filtration, washed with n-hexane and dried. This material was observed to be a fine single crystal under a microscope, and elemental analysis, ESR, SEM and IR
From the results, it was confirmed to be Na _x C ₆₀ (THF) y. (Yield 80%)

Example 3 Under a nitrogen gas atmosphere, 30 mg of commercially available sodium tetraphenylborate was dissolved in 5 ml of THF to obtain 5 mg of C _60.
When this container was irradiated with ultrasonic waves for 5 minutes, the formation of a black suspension was observed in the purple solution. This was collected by filtration, washed with n-hexane and dried. It was confirmed by a microscope that this substance was a fine single crystal, and it was confirmed from the results of elemental analysis, ESR, SEM and IR that it was Na _x C ₆₀ (THF) y. (Yield 85%)

Example 4 Commercially available sodium tetraphenylborate (30 mg) and C using an H-type glass electrolytic cell in a nitrogen gas atmosphere.
₆₀ 5 mg of chlorobenzene / THF = 2: 1 mixed solvent
The solution was dissolved in 15 ml with stirring, and after stirring with ultrasonic waves for 30 minutes or more, electrolysis was performed with a constant direct current (0.7 μA). After a few hours, a black single crystal started to grow on the platinum cathode, but electrolysis was continued for another week. The grown needle-like crystals were collected by filtration and n-
It was washed with hexane and dried. It was confirmed by a microscope that this substance was a fine single crystal, and it was confirmed that it was Na _x C ₆₀ (THF) y in combination with the results of elemental analysis and ESR. (Yield 52%). Among the above examples, the single crystal obtained by the electrolysis method has the highest crystallinity, and it is possible to obtain needle-like or columnar crystals suitable for X-ray crystal structure analysis. The crystal is glossy black and the large one is about 0.3.
It has a size of about x 0.3 x 1.0 mm. The lattice constant obtained by an X-ray four-axis automatic diffractometer is a = 15.310, c =
At 9.914 angstroms, it is suggested to belong to the hexagonal system. From the lattice constant, a structure in which a C ₆₀ ball of about 9.5 Å is packed is estimated. The crystals are stable enough to operate in air for a short time. When the electrical conductivity is measured by the DC four-terminal method, it shows almost metallic conductivity (σ _RT = 50 Scm ⁻¹ ) near room temperature, but as described above, there is a metal-metal transition near 170 K, and
It has a conductivity of up to 1000 Scm ^-1 near K. Furthermore, the behavior at low temperature is sample-dependent. Moreover, from the measurement of the ESR spectrum, C
The presence of ₆₀ anion radicals was confirmed.

Example 5 Potassium tetraphenylborate (synthesized by a conventional method from commercially available sodium tetraphenylborate and potassium chloride) using an H type glass diffusion cell in a nitrogen gas atmosphere.
0 mg was dissolved in 13 ml of THF (partially suspended), and a chlorobenzene solution (26 ml) of 10 mg of C ₆₀ was gently added dropwise. A few days later, a black needle-like single crystal started to grow from the mixed interface of the two liquids. The grown needle-like crystals were collected by filtration and n-
It was washed with hexane and dried. It was confirmed with a microscope that this substance was a fine single crystal, and it was confirmed from the results of X-ray structural diffraction and ESR that it was K _x C ₆₀ (THF) y. (Yield 65%). The obtained compound (K _x C ₆₀ (TH
A photograph of the crystal growth of F) y) is shown in FIG.

Example 6 Barium tetraphenylborate (synthesized by a conventional method from commercially available sodium tetraphenylborate and barium chloride) using an H-type glass diffusion cell under a nitrogen gas atmosphere 5
0 mg was dissolved in 13 ml of THF (partially suspended), and a chlorobenzene solution (26 ml) of 10 mg of C ₆₀ was gently added dropwise. A few days later, a black needle-like single crystal started to grow from the mixed interface of the two liquids. The grown needle-like crystals were collected by filtration and n-
It was washed with hexane and dried. It was confirmed by a microscope that this substance was a fine single crystal, and the presence of C ₆₀ anion radical was confirmed from the result of ESR. (Yield 30
%). A photograph of crystal growth of the obtained compound (Ba _x C ₆₀ (THF) y) is shown in FIG. 7.

Example 7 Lithium tetraphenylborate (synthesized by a conventional method from commercially available sodium tetraphenylborate and lithium chloride) using a H-type glass diffusion cell under a nitrogen gas atmosphere.
0 mg was dissolved in 13 ml of THF (partially suspended), and a chlorobenzene solution (26 ml) of 10 mg of C ₆₀ was gently added dropwise. A few days later, a black needle-like single crystal started to grow from the mixed interface of the two liquids. The grown needle-like crystals were collected by filtration and n-
It was washed with hexane and dried. It was confirmed by a microscope that this substance was a fine single crystal, and the presence of C ₆₀ anion radical was confirmed from the result of ESR. (Yield 70
%). A photograph of crystal growth of the obtained compound (Li _x C ₆₀ (THF) y) is shown in FIG.

[0015]

The metal-doped carbon cluster compound has never been obtained as a single crystal so far, and the wet chemical single-crystal growth method according to the present invention brings a great breakthrough to the physical property research on the metal-doped carbon cluster compound. it is conceivable that. Further, this method can be scaled up, and can be said to be an epoch-making production method suitable for mass production of metal-doped carbon cluster compounds expected as a semiconductor material, a conductive material, or a superconducting material. Even though the conventional method yields only inhomogeneous materials, this manufacturing method, which can obtain high-quality and homogeneous metal-doped carbon cluster compounds, is an extremely excellent method, and also improves productivity and process cost. Since it can be downed, it has great industrial and practical value.

[0016]

[Brief description of drawings]

FIG. 1 is a schematic diagram of Na _x C ₆₀ (TH obtained in Example 1).
F) shows the ESR spectrum of y.

FIG. 2 is a graph of Na _x C ₆₀ (TH obtained in Example 1).
F) y shows a SEM photograph.

FIG. 3 is a graph of Na _x C ₆₀ (TH obtained in Example 1).
F) An IR chart of y is shown.

FIG. 4 is a graph showing the results of Na _x C ₆₀ (TH) obtained in Example 1.
F) shows the temperature change of the resistance value of y.

FIG. 5 is a graph of Na _x C ₆₀ (THF) in Example 1.
It is a photograph of crystal growth of y.

6 is a graph of K _x C ₆₀ (THF) y in Example 5. FIG.
3 is a photograph of the crystal growth of.

FIG. 7 shows Ba _x C ₆₀ (THF) in Example 6.
It is a photograph of crystal growth of y.

FIG. 8 is a graph of Li _x C ₆₀ (THF) in Example 7.
It is a photograph of crystal growth of y.

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[Submission date] May 17, 1994

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FIG. 2 shows Na _X C obtained in Example 1.
_It is a SEM photograph (scanning electron microscope photograph) which shows the crystal structure of ₆₀ (THF) y.

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Claims (3)

[Claims] 1. A metal organic acid salt and a carbon cluster are each dissolved in a soluble organic solvent, and the two liquids are combined and vigorously stirred and mixed under an inert gas stream, or vigorously mixed by ultrasonic irradiation. A method for producing a carbon cluster compound doped with a metal atom, which comprises depositing a fine single crystal of a compound. 2. A metal organic acid salt and a carbon cluster are each dissolved in a soluble organic solvent, and a single crystal of the compound is deposited from the interface between the two liquids by allowing the two liquids to stand and diffuse while being in contact with each other. A method for producing a carbon cluster compound doped with a metal atom, comprising: 3. A carbon cluster compound doped with a metal atom, which comprises growing a single crystal of the compound on the cathode side by electrolytic crystal growth in an organic solvent in which a metal organic acid salt and a carbon cluster are dissolved. Manufacturing method.