JPH05148273A - Copper complex and its production - Google Patents

Abstract

PURPOSE:To obtain a copper raw material for a sol-gel method to realize low- temperature synthesis or to give a desired shape both of which are original characteristics of the sol-gel method in synthesis of copper oxide superconductor by the sol-gel method. CONSTITUTION:A copper complex in which a copper atom is coordinated with a secondary butoxy group and a hydroxy group. The copper complex is produced by using an introduction group-exchanging reaction of a copper compound in a liquid phase with a secondary butoxide of other metal and a hydroxide of other metal or by using a partial hydrolysis reaction of secondary butoxide of copper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper complex and a method for producing the same, and more particularly to a copper complex used for producing a copper oxide superconductor.

[0002]

2. Description of the Related Art There are three main methods for synthesizing a copper oxide superconductor: a solid phase reaction method, a liquid phase reaction method (sol-gel method, coprecipitation method) and a gas phase reaction method (sputtering method, vapor deposition method, CVD method). is there.
The solid-phase reaction method has a simple process and is easy to synthesize, and the liquid-phase reaction method has a possibility of synthesizing at low temperature and giving shape to bulk, film, fiber and the like. Further, the gas phase reaction method can form a thin film. As described above, each of the three synthesizing methods has its own characteristics, and is properly used according to the purpose.

[0003]

However, in the liquid phase reaction method, the characteristic low temperature synthesis or shape imparting has not been sufficiently realized. For example, regarding low temperature synthesis, synthesis of a 124 type superconductor (YBa ₂ Cu ₄ O ₈ ) which is one of copper oxide superconductors is mentioned. This 124 type superconductor (YBa ₂ Cu ₄ O ₈ ) (Natur
e Vol. 336 (1988) p660) is 80K
Although it is a high temperature superconductor of the class, Tc rises up to 90K by substituting a part of Y for Ca (Natur
eVol. 341 (1989) p660). The 124-type superconductor containing Ca was synthesized under high pressure oxygen, but had a relatively high Tc,
It is considered to be a material that is thermally stable and practically important. However, the synthesis requires treatment under high pressure oxygen, and there are difficulties in the synthesis. Recently, using the coprecipitation method, Ca
124 type superconductor including
Example synthesized at 0 ° C. (Physica C Vol. 1)
73 (1991) p208). However, the Tc was 85K, and the increase in Tc due to Ca dove was small, and the superconducting transition was broad. It is considered that this is because the temperature of 820 ° C. was too high for the synthesis of the 124-type superconductor containing Ca.

Regarding the shape imparting, so far,
Precursors such as bulk, film and fiber of copper oxide superconductor by hydrolysis and polycondensation reaction from alkoxide raw material have not been synthesized.

The sol-gel method using an alkoxide is an excellent method that enables low-temperature synthesis or shape formation by synthesizing a homogeneous precursor at the atomic level by hydrolysis and polycondensation reaction. However, conventionally, in the synthesis of copper oxide superconductors, there is no appropriate alkoxide raw material of copper, which is an essential element, and appropriate hydrolysis and polycondensation reactions cannot be caused, so low temperature synthesis or shape imparting is realized. could not. For example, a method of synthesizing a Ca-free 124 type superconductor by Murakami et al.
pan J.P. Appl. Phys. Vol. 29 (1
990) When p2720) is applied to the synthesis of a 124-type superconductor containing Ca, alkoxide raw materials are used for elements other than Cu, but nitrate raw materials are used for Cu, and this crystal water is used as another alkoxide raw material. Is instantly hydrolyzed to precipitate as powder,
The nitrate group is selectively combined with Ba to be precipitated, and at the moment when the Cu nitrate raw material is mixed, all the metal components become powdery,
It cannot be made into fiber, etc., and the effect of Ca dove cannot be fully realized (Tcon = 85K).
The present inventors have found out. In addition, general C such as methoxide, ethoxide, broxide, butoxide, etc.
It was also found that the u alkoxide raw material does not have a practical level of solubility.

The present invention has been made to solve this problem.

An object of the present invention is to provide a copper raw material for the sol-gel method for realizing the low-temperature synthesis or shape imparting which is the characteristic of the original sol-gel method in the synthesis of the copper oxide superconductor by the sol-gel method. ..

The above and other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

[0009]

In order to achieve the above object, the copper complex of the present invention is most characterized in that a copper atom is coordinated with two of a secondary butoxy group and a hydroxyl group.

In the method for producing the copper complex of the present invention,
It is characterized by using a derivatization group exchange reaction between a copper compound and a secondary butoxide of another metal and a hydroxide of another metal in a liquid phase.

In the method for producing the copper complex of the present invention,
It is characterized by using a partial hydrolysis reaction of copper secondary butoxide.

[0012]

According to the above-mentioned means, the copper complex of the present invention has a solubility of about 0.05 M in a butanol solvent, does not decompose other alkoxides, and, by adding water, a hydrolysis reaction. And was confirmed to be useful in the synthesis by the sol-gel method. This contains Ca 1
750 under normal pressure when applied to the synthesis of 24 type superconductor
As a synthesis of a 124 type superconductor at a low temperature of 40 ° C. for 40 hours, it is possible to obtain an almost single phase (Y _{0.95
Ca 0.05) Ba 2 Cu 4 O} y (y~8) superconductor was synthesized. This superconductor shows a sharp X-ray diffraction peak due to the 124 phase, and has a superconducting transition start temperature T due to electric resistance.
c (on) is 89K, zero resistance temperature Tc (R = 0) is 84K, and it shows sharp superconducting transition at high temperature. Moreover, superconducting transition start temperature Tcmag (on) is 90K in magnetization measurement.
Showed a sharp superconducting transition. The superconductor integration ratio also shows the same value as the sample without Ca dosing,
The deterioration of crystallinity due to the dove was considered to be small.

Therefore, when the copper complex of the present invention is used in the sol-gel method, it is possible to synthesize a copper oxide superconductor which cannot be synthesized at a low temperature, such as a Ca-containing 124 type superconductor.

The mixed solution used in the synthesis of the 124 type superconductor containing Ca is spin-coated on a strontium titanate substrate, hydrolyzed in air, and then 75
As a result of heat treatment at 0 ° C in an oxygen stream for 10 hours, Tc (on)
= 79K, Tc (R = 0) = 70K c-axis oriented film was obtained.

Therefore, when the copper complex of the present invention is used in the sol-gel method, it can be shaped into a film.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings.

(Example 1) Method for synthesizing copper complex of the present invention Example 1 and the chemical properties and chemical composition of the copper complex according to the method of Example 1 will be described. The synthesis of the copper complex of Example 1 used the derivatization group exchange reaction of cupric chloride with sodium secondary butoxide and sodium hydroxide in secondary butanol. The reaction formula is shown below.

CuCl ₂ + Na (OBu) + NaOH → (BuO) .Cu.OH + 2NaCl ↓ The obtained suspension was centrifuged to remove NaCl to obtain a butanol solution of a copper complex. Na is contained in the removed solid matter.
The presence of Cl was confirmed by X-ray diffraction, and it was found that an exchange reaction between chlorine in cupric chloride and a secondary butoxy group or a hydroxyl group occurred. The solution had a deep green color, and as a result of inductively coupled plasma emission (ICP) analysis, the concentration as copper was 0.05M. In order to investigate whether this solution decomposes other alkoxides, a copper complex solution was added to a butanol solution in which three butoxides of Y, Ca and Ba were dissolved. The copper complex prepared by the synthesis method of Example 1 was
It was found to not decompose other alkoxides.

Further, when water was added to the copper complex solution, it was suspended in an instant, and when it was centrifuged, it was separated into a dark green solid matter and a transparent solvent. It was found by ICP analysis that no copper component was present in the transparent solvent.

From the above results, the copper complex prepared by the synthesis method of Example 1 was added to 0.05 mol (M) in a butanol solvent.
It can be seen that the sol-gel method dissolves to some extent, does not decompose other alkoxides, and hydrolyzes like alkoxides, and is useful for the sol-gel method.

According to the above-mentioned synthesis method, the ratio of sodium secondary butoxide and sodium hydroxide is changed so that the total of sodium secondary butoxide and sodium hydroxide is 2 atoms per Cul atom. As a result of synthesis, when the ratio of sodium hydroxide is 0, the Cu concentration in the solution is almost 0 (below the detection limit).
Then, when the ratio of sodium hydroxide was 0 to 0.5, the Cu concentration in the solution increased linearly almost in accordance with the equivalent amount of sodium hydroxide.
Almost equal to the equivalent of secondary butoxide (ratio of 1-sodium hydroxide), decreases linearly, and when the ratio of sodium hydroxide is 1, the Cu concentration in the solution is almost 0.
Became. From this, it was found that in the reaction used for the synthesis, the derivatization group exchange reaction of cupric chloride with sodium secondary butoxide and sodium hydroxide proceeds according to the above reaction formula. Therefore, the copper complex prepared by the synthesis method of Example 1 is considered to have a secondary butoxy group and a hydroxyl group coordinated to the copper atom.

Example 2 Example 2 in which the copper complex of the present invention was synthesized by another method will be described.

(1) Synthesis from Various Copper Compounds Copper Nitrate A part of the crystal water of trihydrate of copper nitrate was removed and dissolved in secondary butanol as about monohydrate. A butanol solution in which an equivalent amount of sodium secondary butoxide was dissolved with respect to copper was added to the bright blue solution, and the mixture was stirred and mixed. At the moment of mixing, the solution changed from blue to dark green and was suspended. The solution after centrifugation was dark green and
As a result of CP analysis, it was found that the concentration of the copper component was 0.02M. Once water was added to this solution, it separated into a clear solvent and a dark green solid.

Copper acetate monohydrate The copper acetate monohydrate was dissolved in secondary butanol. Although the solubility was low, a part of it was dissolved and a blue solution was obtained. A butanol solution in which an equivalent amount of sodium secondary butoxide was dissolved in copper was added to this solution and mixed with stirring. The solution changed from blue to brown at the moment of mixing and suspended. The solution after centrifugation was brown and as a result of ICP analysis, it was found that the concentration of the copper component was 0.005M. Once water was added to this solution, it separated into a clear solvent and a brown solid.

Anhydrous Salt of Copper Acetate Copper acetate monohydrate was dried at 100 ° C., and the powder changed from blue green to black was dissolved in secondary butanol. Although the solubility was low, a part of it was dissolved to give a greenish solution. A butanol solution in which an equivalent amount of sodium secondary butoxide and an equivalent amount of sodium hydroxide were dissolved in copper was added to this solution and mixed with stirring. The solution changed from green to brown at the moment of mixing and suspended. The solution after centrifugation was brown, and as a result of ICP analysis, it was found that the concentration of the copper component was 0.004M. Once water was added to this solution, it separated into a clear solvent and a brown solid.

From the above results, it is understood that the copper compound used in the synthesis of the copper complex of the present invention may be any compound which causes an exchange reaction of a derivative group in a solvent. Further, it can be seen that the water of crystallization is useful for the formation of a copper complex if it is in the same amount as copper.

(2) Synthesis Using Secondary Butoxides and Hydroxides of Various Metals Secondary sodium butoxides and hydroxides of sodium, secondary butoxides of lithium, barium and strontium were prepared by the synthesis method of Example 1. And the synthesis was tried by replacing with hydroxide. In either case, 0.05 mol (M)
A solution of the copper complex with a concentration of about 4 was obtained. Once water was added to this solution, it separated into a clear solvent and a brown solid.

From these results, the secondary butoxides and hydroxides used in the synthesis of the copper complex of the present invention are as follows:
It will be understood that any substance that causes an exchange reaction between the copper compound and the derivative group in the solvent may be used.

(3) Synthesis of copper secondary butoxide by partial hydrolysis: Copper chloride secondary butanol solution and sodium secondary butoxide side butanol solution were mixed to form copper secondary butoxide and NaCl. A suspension was obtained. A part of the suspension was taken out and centrifuged, and as a result, the suspension was separated into a transparent solvent and a green solid. It was found by ICP analysis that almost no Cu was present in the transparent solvent. On the other hand, when water was added to the suspension and mixed by stirring, Cu was 0.03 M in the solution after centrifugation.
Was dissolved at a concentration of. Once water was added to this solution, it separated into a clear solvent and a brown solid.

From these results, it is understood that the copper complex of the present invention can be synthesized also by the partial hydrolysis reaction after once synthesizing the copper secondary butoxide.

(Example 3) Example 3 in which the copper complex of the present invention is applied to the synthesis of a 124-type superconductor containing Ca will be described.

FIG. 1 illustrates the application of the copper complex of the present invention 124.
3 is a schematic diagram for explaining the crystal structure of a type superconductor (YBa ₂ Cu ₄ O ₈ ), where 1 is barium (Ba), 2 is copper (Cu), and 3 is oxygen (O) on the intersection of lattices. 4 is yttrium (Y).

FIG. 2 is a flow chart for synthesizing a 124-type superconductor containing Ca. The three solutions in which butoxides of Y, Ca, and Ba are dissolved and the butanol solvent of the copper complex of the present invention are Y: Ca: Ba: Cu (1-
x): x: 2: 4 (x = 0, 0.05) and weigh it (step 101), and 2 at 70 ° C. in an argon stream.
Mix for 0 hours (step 102). Air in the room was introduced into this solution at a flow rate of 50 ml / min for 30 minutes to cause hydrolysis (step 103). 1 suspended liquid
A gel was formed by evaporating and drying while pulling a vacuum at 20 ° C. (step 104). The obtained gel powder is vacuumed at 500 ° C.
And dried for 1 hour to give a dry powder (step 10
5). Then, the dry powder is molded into a mold (step 10
6) Then, firing was carried out in an oxygen stream at each temperature for 40 hours (step 107). FIG. 3 is a diagram showing a powder X-ray diffraction pattern of a gel powder of x = 0.05 and a sample fired at 750 ° C. and 800 ° C., respectively. From FIG. 3, the gel powder has no diffraction peaks other than the diffraction peak of NaCl, which is the residue, and Y, which is a constituent component of the 124 type superconductor containing Ca
It can be seen that Ca, Ba and Cu exist in an amorphous form and are not segregated. Further, all the fired samples show a sharp diffraction peak due to the 124 phase, and almost no diffraction peak due to the impurity phase is observed. Figure 4
Shows the temperature dependence of the electrical resistivity of the samples fired at x = 0.05 at 750 ° C. and 800 ° C., respectively. Both are Tc (o
Although n) is the same, Tc (R = 0) is higher in the sample fired at 750 ° C., and the superconducting transition is sharper. From this, it is difficult to understand from the X-ray diffraction pattern, but Ca
It is considered that the 124-type superconductor containing C is partially decomposed at 800 ° C. under normal pressure and the crystallinity is beginning to deteriorate. Figure 5 shows x = 0 and x = 0.05 baked at 750 ° C.
Showing the powder X-ray diffraction pattern of the sample of FIG.
FIG. 7 is a graph showing the temperature dependence of the electrical resistivity of the samples of x = 0 and x = 0.05 baked at 0 ° C. FIG. 7 shows the magnetization of the samples of x = 0 and x = 0.05 baked at 750 ° C. It is a figure which shows the temperature dependence of a rate. The samples with x = 0 and x = 0.05 both show only sharp diffraction peaks due to the 124 phase, and also show a sharp superconducting transition both electrically and magnetically, and are 124 type superconducting materials with good characteristics. I know that I have a body.
There is no other example of synthesizing a 124-type superconductor containing Ca having such good characteristics under normal pressure, and it can be said that the method of using the copper complex of the present invention as a raw material has a remarkable effect in low-temperature synthesis.

Further, the low temperature synthesis method using the copper complex of the present invention as a raw material has been confirmed to be effective in the synthesis of other copper oxide superconductors. For example, the copper complex of the present invention and Y, Ba
When the 123 type superconductor is synthesized under vacuum using the butoxide of No. 6 as a raw material, it is about 50 ° C. lower than the conventional method.
Synthesized at 0 ° C.

(Example 4) Example 4 in which the copper complex of the present invention is applied to the formation of a 124-type superconductor thin film will be described.

The mixed solution prepared in Example 3 was spin-coated on a strontium titanate substrate. This was hydrolyzed in air, dried in vacuum at 500 ° C. for 1 hour, and then heat-treated in an oxygen stream at 750 ° C. for 10 hours. The synthesized film was black translucent and had a film thickness of about 1 μm. As a result of X-ray diffraction by a normal θ-2θ scan,
Only the (001) peak of the 124 type superconductor is observed,
It was found that the synthesized film was a c-axis oriented film of 124 type superconductor. As a result of measuring the temperature dependence of the electrical resistivity, a superconducting transition of Tc (on) = 79K and Tc (R = 0) = 70K was shown.

From these results, it is understood that the copper complex of the present invention is effective for forming a copper oxide superconductor film.
Further, it is expected that by appropriately controlling the hydrolysis reaction, it is possible to impart a shape to a bulk, a fiber or the like.

Although the present invention has been specifically described based on the embodiments, it is needless to say that the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention.

For example, the present invention relates to a 123 type superconductor (Y
In the synthesis of Ba ₂ Cu ₃ O ₇ ) and bismuth-based superconductors, of course, the homogeneity of the precursor has the effect that it can be synthesized in a shorter time than the usual solid-phase reaction method.

[0040]

As described above, according to the present invention, a precursor of a copper oxide superconductor can be formed into a desired shape such as a bulk, a film or a fiber by controlling a hydrolysis reaction. Is possible. In addition, a copper oxide superconductor that can be synthesized only at low temperature,
Alternatively, even an ordinary copper oxide superconductor can be synthesized in a short time at a temperature lower than the conventional one.

[Brief description of drawings]

FIG. 1 is a 124-type superconductor (YB of Example 3 of the present invention).
a ₂ Cu ₄ O ₈ ) schematic diagram for explaining the crystal structure of

FIG. 2 is a flow chart of the synthesis of Example 3 in which the copper complex of the present invention is applied to the synthesis of a 124-type superconductor containing Ca,

FIG. 3 is a powder X-ray diffraction pattern of a gel powder of x = 0.05 and a fired sample according to Example 3;

FIG. 4 is a resistivity-temperature characteristic diagram of a fired sample of x = 0.05 according to Example 3;

FIG. 5 is a powder X-ray diffraction pattern of a fired sample of x = 0 and x = 0.05 according to the third embodiment,

FIG. 6 is a resistivity-temperature characteristic diagram of the fired samples of x = 0 and x = 0.05 according to the third embodiment.

FIG. 7 is a magnetic susceptibility-temperature characteristic diagram of a fired sample of x = 0 and x = 0.05 according to the third embodiment.

[Explanation of symbols]

1 ... Barium (Ba), 2 ... Copper (Cu), 3 ... Oxygen (O) on the intersection of lattices, 4 ... Yttrium (Y).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Koriyama 1-14-3 Shinonome, Koto-ku, Tokyo Inside the Superconducting Engineering Laboratory, Research Center for International Superconductivity Technology (72) Inventor Takaaki Ikemachi Shinonome, Koto-ku, Tokyo 1-14-3 International Superconductivity Industrial Technology Research Center Superconductivity Engineering Laboratory (72) Inventor Nao Yamauchi 1-14-3 Shinonome, Koto-ku, Tokyo International Superconductivity Industrial Technology Research Center Superconductivity Engineering Laboratory

Claims (3)

[Claims] 1. A copper complex in which a secondary butoxy group and a hydroxyl group are coordinated with a copper atom. 2. The derivatization group exchange reaction between a copper compound and a secondary butoxide of another metal and a hydroxide or a hydroxyl group of another metal in a liquid phase is used. Method for producing copper complex. 3. The method for producing a copper complex according to claim 1, wherein a partial hydrolysis reaction of copper secondary butoxide is used.