JP2514685B2 - Superconducting material and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to superconducting materials. More specifically, the present invention relates to a novel superconducting material having a high superconducting critical temperature, a small difference between the superconducting critical temperature and the end temperature of phase transition, and stable superconducting properties, and a method for producing the same.

2. Description of the Related Art A substance under superconducting phenomenon exhibits complete diamagnetism, and no potential difference appears even though a finite steady current flows inside. Therefore, various applications have been proposed for a superconductor as a transmission medium having no power loss.

That is, MHD power generation, power transmission, power storage and other power fields,
Alternatively, power fields such as magnetic levitation trains and electromagnetic propulsion vessels,
Furthermore, as ultra-sensitive sensors for magnetic fields, microwaves, radiation, etc., there are numerous fields of application, such as the fields of measurement such as NMR, pion therapy, and high energy physics experimental equipment.

Also, in the field of electronics represented by Josephson devices, it is expected as a technology that can realize not only simple power consumption but also extremely high-speed operation.

By the way, so far, the superconducting phenomenon has been observed only under ultra-low temperature. That is, Nb ₃ Ge, which is said to have the highest superconducting critical temperature Tc as a conventional superconducting material, remains at 23.2K. Therefore, conventionally, in order to realize the superconducting phenomenon, liquid helium having a boiling point of 4.2K was used to cool the superconducting material to Tc or lower. However, the use of liquid helium has a very large technical burden and cost burden due to the cooling equipment including the liquefaction equipment,
It was an obstacle to the practical application of superconducting technology.

However, with the discovery of superconducting oxides with a high T _c in the fall of 1986, the possibility of high-temperature superconductivity opened up significantly (Bednorz, Muller, “Phys.B64 (1986) 18
9). This oxide superconductor is [La, Ba] ₂ CuO ₄ or [La,
Sr] ₂ CuO ₄ , which is called K ₂ NiF ₄ type oxide,
It has a similar crystal structure to the conventionally known perovskite type superconducting oxide. The T _{c of} these substances is 30-50K,
The value is dramatically higher than before. When T _c reaches this temperature, liquid hydrogen (boiling 20.4K) or liquid neon (boiling point 27.3K) is so used as a refrigerant for causing the superconducting.

Furthermore, in February 1987, a news report was published by Chu et al. That a Ba-Y-based complex oxide exhibiting a critical temperature of 90K was discovered, and the possibility of realization of a non-low temperature superconductor is faint. It is rising.

Problems to be Solved by the Invention Tc generally means a starting temperature of a superconducting phenomenon or a critical temperature at which superconductivity cannot be maintained, but depending on a substance, an end temperature of a phase transition at which the substance becomes a perfect superconductor.
Tcf is far apart from Tc. Therefore, it is actually necessary to cool the temperature to a temperature considerably lower than Tc, and from this point, it is desired to minimize the difference between Tc and Tcf.

Further, it is known that a superconductor loses its superconducting effect in a magnetic field having a certain strength or more. It is known that the magnetic field and magnetic field in which this superconductor loses its characteristics generally rises and falls with the critical temperature of the substance. Especially when considering its application to high-field electromagnets, etc. The need to improve stability is discussed.

Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, while maintaining a high T _c , without losing the superconducting effect even under a high magnetic field, a novel superconducting material with a small difference between Tc and Tcf. , To provide a manufacturing method for obtaining the superconducting material.

In the following description, the superconducting start temperature or critical temperature of the superconducting material is represented by Tc, the phase transition end temperature at which the electric resistance of the material is completely zero is represented by Tcf, and the difference between Tc and Tcf is represented by ΔT.

Means for Solving the Problems The present inventors have tried to solve the above problems by adding another additive element to the room temperature superconducting material as described above which has been recently discovered. That is, the characteristics of the superconducting material are improved by adding other elements, and as a result, the superconducting characteristics such as improvement of the critical current density Jc and stabilization of Jc under a high magnetic field are improved. Tried.

As a result of experiments, the present inventor found that V, Ta, Nb, Cr, Ga, In, C
While maintaining a high T _c by adding one or more of d, Sn, Tl, Pb, Mo, W, or Zn, the superconducting effect is not lost even in a high magnetic field, and Tc and Tcf It was found that a superconducting material with a small difference can be obtained.

Therefore, according to the present invention, according to the general formula: α _u β _v γ _w δ _x ε _y (where α is 1 selected from the groups IIa and IIIa of the periodic table).
Β is a kind selected from elements including the same as α in Group IIa and IIIa of the Periodic Table, and δ is Group Ib, IIb, IIIb and VIIIa of the Periodic Table. 1 is selected from the elements, ε is at least one selected from O, B, C, N, F and S, and γ is V, Ta, Nb, Cr, Ga, In, Cd , Sn, Tl, Pb, Mo,
At least one selected from the group consisting of W and Zn, u, v, w, x is a number of 0 or more and 1 or less, and y is a number of 1 or more and 4 or less) A superconducting material is provided.

As the superconducting material according to the present invention, the following compounds can be specifically mentioned as typical examples.

In the above general formula, ε is O, and the superconducting material is a composite oxide.

In the above general formula, δ is Cu, and the composite oxide represented by the above general formula is a superconducting material characterized in that it is a perovskite type oxide or a pseudo perovskite type oxide. Being a group element, β is the periodic table
A superconducting material characterized by being a group IIIa element.

According to one aspect of the present invention, the superconducting material is obtained as, for example, a sintered body. Further, according to another aspect, it is also formed as a thin film formed by vapor phase synthesis.

That is, according to the present invention, as a method for producing the above-mentioned superconducting material, 1 selected from Group IIa and IIIa elements of the periodic table.
A certain element α, and one element β selected from elements of the periodic table IIa and IIIa group elements containing the same as α, V, T
at least one element γ selected from the group consisting of a, Nb, Cr, Ga, In, Cd, Sn, Tl, Pb, Mo, W, and Zn, and Ib, IIb, IIIb, VIII of the periodic table A method for producing a superconducting material comprising a composite oxide, characterized by sintering a mixture of powders of oxides, carbonates, sulfates or nitrates with one element δ selected from the group a elements. Provided.

As the superconducting material obtained by the manufacturing method according to the present invention, δ in the general formula is Cu, the superconducting material in which the composite oxide is a perovskite type oxide or a pseudo perovskite type oxide, or the α Is a group IIa element of the periodic table, and β is a group IIIa element of the periodic table.

More specifically, there is a superconducting material in which α is Ba and β is Y. According to one aspect of the present invention, Ba,
The atomic ratio of Y, Cu and the element represented by the above symbol γ is (0.
5 to 2): (0.5 to 3): (1 to 4): Mixing powders of oxides, carbonates, nitrates or sulfates of Ba, Y, Cu and element δ so as to be (0.01 to 0.1). Is mentioned.

In the production method of the present invention, according to a preferred embodiment of the present invention, the sintering is 700 to 1600 ° C., preferably 800 to 1600 ° C.
Preference is given to working at temperatures in the range of 1000 ° C.

Further, it is advantageous to carry out the above-mentioned sintering in at least two stages of pre-sintering in which the mixed powder is pre-sintered and main sintering in which the pre-sintered sintered body is crushed, molded and then sintered. Is.

Here, according to a preferred embodiment of the present invention, it is advantageous to carry out the pre-sintering at a temperature in the range of 550 to 950 ° C. and the main sintering at a temperature in the range of 800 to 930 ° C., respectively.

In addition, immediately after the above sintering, or immediately after quenching, or after sintering,
It is also preferable to perform a treatment including a step of reheating in the range of 700 to 930 ° C. and quenching.

Further, according to the present invention, one element α selected from Group IIa and IIIa elements of the Periodic Table, and Periodic Tables IIa and IIIa
One element selected from the group of elements including the same as α, β, V, Ta, Nb, Cr, Ga, In, Cd, Sn, Tl, Pb, M
Oxide containing at least one element γ selected from the group consisting of o, W, and Zn and one element δ selected from Group Ib, IIb, IIIb, and VIIIa elements of the periodic table There is provided a method for producing a superconducting thin film, characterized by forming a thin film of a perovskite type oxide or a pseudo perovskite type oxide by performing physical vapor deposition using as a target.

Here, according to a preferred embodiment of the present invention, the target is a perovskite type oxide or a pseudo perovskite type oxide.

In the above method, according to one aspect of the present invention, the element α is Ba, the element β is Y, and the element δ is Cu. Here, the atomic ratio of Ba, Y, Cu and the element represented by the symbol γ is (0.5 to 2) :( 0.5 to 3) :( 1 to 4):
It is advantageous to prepare powders of oxides, carbonates, nitrates or sulphates of Ba, Y, Cu and the element δ so that they are (0.01-0.1).

The target is a mixed powder of Ba, Y, Cu and an oxide, carbonate, nitrate or sulfate of the above element δ.
It may be one which is fired at a temperature of 250 to 1200 ° C., and it is further advantageous that the above target is further sintered after the above firing at a temperature in the range of 700 to 1000 ° C.

As the target, a powder of the main sintered body or the pre-sintered body may be used as the target, or a block may be used.

It is also possible to use a plurality of targets, in which case, according to one aspect of the invention, the targets may each be Ba, Y, Cu and an oxide of the element δ.

Here, according to a preferred embodiment of the present invention, the atomic ratio of Ba, Y, Cu and the element δ of the target is Ba, Y, Cu and Cu based on the atomic ratio of Ba, Y and Cu of the thin film to be formed. It is advantageous that it is adjusted according to the vapor deposition efficiency of the element δ.

The vapor deposition atmosphere contains Ar and O ₂ , and the Ar partial pressure is 1 × 10.
^{It is} preferable that the O ₂ partial pressure is within the range of ^{−3 to} 3 × 10 ⁻¹ Torr and the range of O ₂ partial pressure is within the range of 1.0 × 10 ^{−3 to} 3 × 10 ⁻¹ Torr.

Further, the physical vapor deposition may be RF sputtering, and in this case, the high frequency power during sputtering is preferably 104 W / cm ² or less.

Further, the vapor deposition can be performed by magnetron sputtering.

According to a preferred embodiment of the present invention, it is advantageous to heat the substrate with a heater during sputtering,
The heating temperature is advantageously in the range of 260 to 1500 ° C.

According to one embodiment of the present invention, the substrate is glass,
It is possible to use one selected from the group consisting of quartz, Si, stainless steel and ceramics.

The distance between the substrate and the target during vapor deposition is 3 to 23.
It is preferably in the range of 0 mm.

Further, the physical vapor deposition may be any one of ion plating, vacuum vapor deposition, ion beam vapor deposition, and molecular beam vapor deposition.

As described above, the superconducting material obtained as a sintered body or a thin film according to the present invention is preferably further heat-treated. Here, according to one embodiment of the present invention, the heating temperature is preferably in the range of 750 to 1500 ° C, and 750 to
More preferably, it is within the temperature range of 930 ° C.

Action The superconducting material provided by the present invention is represented by the general formula: α _u β _v γ _w δ _x ε _y (where α is one element selected from Group IIa and IIIa elements of the periodic table, and β is a periodic element). It is one kind selected from elements including the same elements as α in Group IIa and IIIa of the Periodic Table, and δ is one kind selected from Group Ib, IIb, IIIb and VIIIa elements of the Periodic Table. And ε is at least one selected from O, B, C, N, F and S, and γ is V, Ta, Nb, Cr, Ga, In, Cd, Sn, Tl, Pb, Mo,
At least one selected from the group consisting of W and Zn, u, v, w, x is a number of 0 or more and 1 or less, and y is a number of 1 or more and 4 or less) .

Generally, the element ε is oxygen (O), but some of it is selected from B (boron), C (carbon), N (nitrogen), fluorine (F) and sulfur (S). It may be replaced by an element, especially fluorine (F).

Further, the element δ is generally copper (Cu), but a part of the element δ may be another element selected from Group Ib, IIb, IIIb, and VIII elements, for example, titanium (Ti). It may be replaced.

Further, the element α is generally a Group IIa element of the periodic table, the element β is generally a Group IIIa element of the periodic table,
Particularly preferable combinations include a Ba—Y combination in which α is Ba and β is Y, and a Sr-La combination in which α is Sr and β is La. Furthermore, these α and β
May be partially replaced with another element of Group IIa element of the periodic table, for example, calcium (Ca) or the like.

The atomic ratio of the elements α, β, γ and δ, that is, u,
v, w and x are numbers of 0 or more and 1 or less and are appropriately selected according to the combination of each element. For example, Ba-Y-Cu-γ
In the case of a complex oxide of the system, the atomic ratio Ba: Y: Cu: γ of Ba, Y, Cu and the element represented by the above symbol γ is (0.5 to 2):
(0.5 to 3): (1 to 4): (0.01 to 0.1). That is, when the atomic ratio of each element is within the above range, the probability that a perovskite-type or pseudo-perovskite-type crystal structure that exhibits effective superconducting properties is formed increases.

Such a superconducting material according to the present invention can be manufactured as follows.

That is, as one method, the periodic table IIa, IIIa
An element α selected from the group of elements and a periodic table IIa,
One element β selected from the group IIIa elements including the same as α, and V, Ta, Nb, Cr, Ga, In, Cd, Sn, T
at least one element γ selected from the group consisting of l, Pb, Mo, W, and Zn and one element δ selected from Group Ib, IIb, IIIb, and VIIIa elements of the periodic table Sinter each oxide, carbonate, sulfate or nitrate powder.

Here, the elements α, β, γ and δ and the atomic ratios of these elements, that is, u, v, w and x are adjusted so that the above definition is satisfied after sintering. The sintered body thus obtained is a composite oxide containing the above elements α, β, γ and δ. As described above, a part of the oxygen of this composite oxide is another element selected from the above elements ε other than oxygen, that is, B (boron), C (carbon), N (nitrogen), fluorine ( It is also possible to substitute F) and / or sulfur (S), especially fluorine (F). These elements are generally added to the raw powder mixture in powder form in the form of nitrides, such as BN and CN, or fluorides or sulfides of the above elements α, β, γ and δ, such as barium fluoride and yttrium fluoride. It can be added in the form to the raw powder mixture. Further, these elements or their compounds can be directly added in a gaseous state.

The above sintering is preferably carried out at a temperature in the range of 700 to 1600 ° C, preferably 800 to 1000 ° C. That is, when the sintering temperature does not reach this range, the effective solid-phase reaction does not proceed or becomes extremely slow. On the other hand, when the amount exceeds the above range, a part of the raw material powder is melted and the formation of a perovskite or pseudo perovskite type crystal structure is hindered.

Further, this sintering operation is carried out in at least two stages of pre-sintering in which the mixture of the powders is pre-sintered, and main sintering in which the pre-sintered sintered body is crushed, molded, and then sintered. Is extremely advantageous. That is, by carrying out such an operation, homogenization of the sintered body and prevention of crystal coarsening are achieved. As a preferable processing temperature, the pre-sintering is performed at a temperature in the range of 550 to 950 ° C, and the main sintering is performed at 800 to 9 ° C.
It is exemplified to carry out at a temperature in the range of 30 ° C.

According to one aspect of the present invention, the superconducting material according to the present invention can be formed as a thin film. That is,
One element α selected from Group IIa and IIIa elements of the Periodic Table, one element β and V selected from elements including the same as α in the Periodic Tables IIa and IIIa Ta, Nb, Cr, Ga,
At least one element γ selected from the group consisting of In, Cd, Sn, Tl, Pb, Mo, W and Zn, Ib, IIb and III of the periodic table
b, physical vapor deposition is performed using an oxide containing one element δ selected from Group VIII a elements as a target, and a composite oxide that is considered to have a perovskite type oxide or a pseudo perovskite type crystal structure is formed as a thin film. Can be synthesized.

Here, the crystallinity of the thin film is more precisely controlled by using, as the target, one that is a perovskite type oxide or a pseudo perovskite type oxide. That is, it is extremely effective to use the superconducting composite oxide obtained as the above-mentioned sintered body as a target. In addition, when manufacturing the complex oxide sintered body as a target, all the various operations when manufacturing the superconducting material of the above-mentioned sintered body can be applied.

The target may be a powder of the above-mentioned main sintered body or temporary sintered body or a block of the sintered body or temporary sintered body. further,
Multiple targets can also be used. In this case, each target can be each oxide of Ba, Y, Cu and the element δ.

The atomic ratio of Ba, Y, Cu and element δ of the above target should be adjusted according to the vapor deposition efficiency of Ba, Y, Cu and element δ with reference to the atomic ratio of Mg, Th and Cu of the thin film to be formed. You can

The thin film can be formed on a substrate such as glass, quartz, Si, stainless steel, and ceramics such as strontium titanium oxide, magnesia, and YSZ.

As described above, a part of oxygen of this composite oxide is another element selected from the above elements ε other than oxygen, that is, B (boron), C (carbon), N (nitrogen), It is also possible to replace with fluorine (F) and / or sulfur (S), especially fluorine (F). In this case, generally, these elements are added to the raw material powder mixture in the form of a powder in the form of nitride, for example, a powder in the form of BN, CN or the like, or a fluoride or sulfide of the above elements α, β, γ and δ is added. These elements can be incorporated into the thin film by adding them to the raw material powder mixture in the form of a substance such as barium fluoride or yttrium fluoride. Further, it can be added by adding these elements or their compounds in a gaseous state into the physical vapor deposition atmosphere.

The physical vapor deposition can be performed by sputtering, ion plating, vacuum vapor deposition, ion beam vapor deposition, molecular beam vapor deposition, but in particular, RF sputtering, further, it is preferable to perform by magnetron sputtering, the high frequency power during sputtering is 104W. It is preferably not more than / cm ² . The distance between the substrate and the target is preferably in the range of 3-230 mm. Also, during sputtering,
It is also effective to heat the substrate with a heater to a temperature in the range of 260 to 1500 ° C.

The physical vapor deposition atmosphere contains Ar and O ₂ , and the Ar partial pressure is 1 × 10 ^-3
To 3 × 10 ^-1 Torr, in this case
It is advantageous to have the O ₂ partial pressure in the range 1.0 × 10 ^-3 to 3 × 10 ^-1 Torr.

The superconducting material produced by various methods according to the present invention as described above can be homogenized and stabilized in composition by further heat treatment after production. Here, a preferable processing temperature is 750 to 1500 ° C.,
Preferably, the temperature range of 750 to 930 ° C can be mentioned. In addition, this heat treatment can also be performed in an atmosphere having an oxygen partial pressure of 10 ^-1 atm or less to control the oxygen content in the superconducting material.

Hereinafter, the present invention will be described in more detail with reference to examples, but the following examples are examples of the present invention and do not limit the technical scope of the present invention.

Example First, an apparatus used for carrying out the method of the present invention will be described. FIG. 1 is a schematic diagram of a high-frequency sputtering apparatus used for producing a superconducting oxide thin film of the present invention.

The apparatus shown in FIG. 1 is provided in opposition to a raw material target 2, a chamber 1, a target 2 disposed in the chamber 1, a sputter power source 3 juxtaposed to sputter this target with sputter atoms. And a substrate 4 on which a thin film is to be formed on the surface. The chamber 1 is connected to a vacuum pump (not shown) via a port 7 so that the inside can be evacuated.

A bias voltage is applied to the substrate 4 using a high-voltage power supply 5. The substrate 4 is further provided with a heater 6 for heating so that the substrate temperature can be adjusted. Furthermore, chamber 1
Is provided with a gas introduction hole 8.

FIG. 2 is a schematic view of a high frequency excitation type ion plating apparatus used for producing the superconducting oxide thin film of the present invention.

The apparatus shown in FIG. 2 includes a chamber 11, a raw material target 12 disposed in the chamber 11, an electron gun 13 juxtaposed to melt and vaporize the raw material target with an electron beam, and a raw material target 12. Provided
It mainly comprises a substrate 14 on which a thin film is formed on the surface. The chamber 11 is connected to a vacuum pump (not shown) so that the inside can be evacuated.

A bias voltage is applied to the substrate 14 using a high voltage power supply 14. The substrate 14 is further provided with a heating heater 16 so that the substrate temperature can be adjusted. In the chamber 11, a high-frequency coil 17 is further provided between the raw material target 12 and the substrate 14 so as to cover the evaporated particles. Further, the chamber 11 is provided with a gas introduction hole 18 for introducing oxygen.

Preparation Example 1 A mixture of 59.0 g of BaCO ₃ powder having a purity of 99.9%, 45.0 g of Y ₂ O ₃ powder having a purity of 99.9%, and 40.0 g of CuO powder having a purity of 99.99%,
Further, 2.0 g of V ₂ O ₅ powder having a purity of 99.9% was added, pulverized by a ball mill and well mixed.

Subsequently, this mixture was molded by embossing, and the molded body was fired at 930 ° C. for 12 hours in the atmosphere. The fired body was crushed by a ball mill and then molded again, and the molded body was sintered in the atmosphere at 930 ° C. for 12.5 hours.

A sample member of about 3 × 3 × 10 mm was cut out from the thus obtained sintered body, electrodes were formed on both ends of this sample member by gold vapor deposition according to a conventional method, and a DC 4-point probe was prepared while cooling in a cryostat. The resistance was measured by the method. Calibrated Au (F
e) -Ag thermocouple was used.

After confirming that the member cooled to about 21 K by liquid hydrogen shows a superconducting phenomenon, when observing the change in resistance while gradually raising the temperature of the member by the heater, the member began to show resistance from 52 K, After reaching 93K, it began to show the same electrical resistance as normal. That is, the critical temperature Tc of the superconducting material manufactured in this manufacturing example is 93
K and the end temperature of the phase transition is 52K. This was also confirmed from the measurement result of the AC magnetic susceptibility measured using the L meter.

Next, when the critical current density Jc was measured according to a conventional method for a sample member similar to the above, 600 A / 80 K at 80 K
A current density value of cm ² was observed. When the external magnetic field was raised at this temperature and the change in the critical current density Jc was measured, a current density value of 100 A / cm ² was observed at a magnetic field of 1 Tesla.

Preparation Example 2 59.0 g of BaCO ₃ powder having the same purity as that of Preparation Example 1 and 99.9%, and purity
45.0 g of 99.9% Y ₂ O ₃ powder and 40.0 g of 99.99% pure CuO powder
In this preparation example, the purity of 99.9%
5.0 g of Ta ₂ O ₅ powder was added, pulverized with a ball mill and mixed well.

Subsequently, this mixture was molded by embossing, and the molded body was baked at 930 ° C. for 12 hours in the atmosphere. The fired body was crushed by a ball mill and then molded again, and the molded body was sintered in the atmosphere at 930 ° C. for 12.5 hours.

A sample member of about 3 × 3 × 10 mm was cut out from the thus obtained sintered body, and the critical temperature and the temperature at which the resistance of the sample member became completely zero were measured by the same method as in Preparation Example 1. The critical temperature Tc of the superconducting material of this preparation example was 77K, and the end temperature of the phase transition was 76K.

This result was also confirmed from the measurement result of the AC susceptibility measured using the L meter.

Although the critical temperature of the superconducting material of this preparation example is lower than that of the material of the first preparation example, it should be noted that in this sample, the difference between the critical temperature and the phase transition end temperature is extremely small. is there.

Next, when the critical current density Jc was measured according to a conventional method for a sample member similar to the above, it was 500 A / 70 at 70K.
A current density value of cm ² was observed. When the external magnetic field was raised at this temperature and the change in the critical current density Jc was measured, a current density value of 80 A / cm ² was observed at a magnetic field of 1 Tesla.

Preparation Example 3 Ba ₂ CO ₃ , Y ₂ CO ₃ , and CuO powders were mixed at an atomic ratio of Ba / (Ba + Y).
Is 0.4 and the atomic ratio Ba / Cu is 2/3, and V ₂ O ₅ powder is further added so that the V / Ba ratio is 0.67 in terms of atomic ratio. Was temporarily sintered, pulverized and molded, and then further main-sintered at 1080 ° C. to obtain a sintered block. Using this block as a target, a thin film was formed by a sputtering method using a Si single crystal substrate under the following conditions.

Oxygen partial pressure 4 × 10 ^-2 Torr, Ar partial pressure 3 × 10 ^-2 Torr, substrate temperature 700 ° C, substrate bias voltage -60V, high frequency power 25W / cm ² , distance between substrate and target 40mm, deposition rate 3Å A film having a thickness of about 1 μm was formed at a time of / sec.
For comparison, the other conditions were the same, and the same operation was performed in an atmosphere containing no O ₂ to form a thin film.

Next, a sample was prepared to measure the resistance of each of the obtained thin films. In the sample for performing the resistance measurement, a pair of Al electrodes was further formed on both ends of the thin film formed on the substrate by vacuum evaporation, and a lead wire was soldered to the Al electrode.

The thin film produced by the method of the present invention, in which the oxygen partial pressure inside the chamber is 4 × 10 ⁻² Torr, has a temperature at which the superconducting phenomenon starts is about 90K, and becomes a perfect superconductor at 50K or less. In contrast, thin films made without oxygen in the chamber
The resistance started to drop at about the same temperature, but the drop was gentle and became a complete superconductor for the first time around 7K. This indicates that the oxygen in the thin film can be appropriately controlled by introducing oxygen into the chamber during film formation, and a superconducting thin film having a desired composition can be formed.

The critical current density Jc of the thin film sample of the present invention is 2,000 A / cm ₂ at 70 K, and when the change of the critical current density Jc was measured by raising the external magnetic field at this temperature, it was 840 A / cm ² at the magnetic field of 1 Tesla. The current density value of was observed.

Preparation Example 4 Ba ₂ CO ₃ , Y ₂ CO ₃ , and CuO powders were mixed at an atomic ratio of Ba / (Ba + Y).
Is 0.4 and the atomic ratio Ba / Cu is 2/3, and then Ta ₂ O ₅ powder is added so that the Ta / Ba ratio becomes 0.77 in terms of atomic ratio, and after molding, 820 ° C. Was temporarily sintered, pulverized and molded, and then further main-sintered at 1080 ° C. to obtain a sintered block. Using this block as a target and using a Si single crystal substrate, a thin film was formed by a sputtering method under the same conditions as in Preparation Example 3. Hereinafter, in the same manner as in Production Example 3, a sample was produced to measure the resistance of each thin film obtained.

The thin film produced by the method of the present invention had a temperature at which the superconducting phenomenon started was about 76 K, and at 75 K, it became a complete superconductor as early as possible. Also in this sample, it was confirmed that the difference between the critical temperature and the phase transfer end temperature was extremely small.

The critical current density Jc of this thin film sample is 3,0 at 70K.
It was 00A / cm ₂ , and the change of the critical current density Jc was measured by increasing the external magnetic field at this temperature.
A current density value of 0 A / cm ² was observed.

Effects of the Invention As described above in detail, according to the present invention, a novel superconducting material having an extremely high Tc is provided. Since the novel superconducting material exhibits a high Tc as described above, it is no longer necessary to use liquid helium which is expensive and difficult to obtain, and liquid hydrogen or liquid neon which is easily available can be used. Further, it is possible to use extremely inexpensive liquid nitrogen, which is secondarily produced due to the enormous demand for liquid oxygen, and it is possible to remarkably expand the range of application of superconducting technology.

Further, since the superconducting material according to the present invention is obtained as a sintered body, if various applied technologies realized by the recent development of the sintered body-related field are used, products of various shapes or dimensions can be obtained. It is possible. Therefore, it can be used as a main member such as a high magnetic field electromagnet, a superconducting power transmission line, a superconducting power accumulator, etc., and a thin film can be formed by using this superconducting material as a target. Applications in the field of microelectronics will also expand.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of a sputtering apparatus used for carrying out the method of the present invention, and FIG. 2 is a schematic view of an example of an ion plating apparatus used for carrying out the method of the present invention. [Main reference numbers] 1,11 …… Chamber, 2,12 …… Target, 3 …… Sputtering power supply, 4,14 …… Substrate, 5,15 …… High voltage power supply, 6,16 …… Heater, 7… … Port, 8,18 …… Gas inlet, 13 …… Electronic gun

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C01G 1/00 C01G 1/00 S 1/06 ZAA 1/06 ZAA 1/12 ZAA 1/12 ZAA C04B 35/45 ZAA C23C 14/08 ZAAL C23C 14/08 ZAA 14/34 ZAAQ 14/34 ZAA H01B 12/00 ZAA H01B 12/00 ZAA H01L 39/24 ZAAB H01L 39/24 ZAA C04B 35/00 ZAAK (72 ) Inventor Saburo 1-1 1-1 Kunyokita, Itami-shi, Hyogo Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Shuji Yazu 1-1-1 Kunyo-kita, Itami-shi, Hyogo Sumitomo Electric Industries In Itami Manufacturing Co., Ltd. (72) Inventor Tetsuji Kamishiro 1-1-1 Kunyokita, Itami City, Hyogo Prefecture Sumitomo Electric Industries, Ltd. Itami Works (56) Reference JP-A-63-224112 (JP, A) JP-A-63-225531 (JP, A)

Claims (3)

(57) [Claims] 1. A general formula: α _u β _v γ _w δ _x ε _y [where α is
Is one selected from the IIa and IIIa groups of the periodic table,
β is one element selected from elements including the same elements as the element α in Group IIa and IIIa of the Periodic Table, and δ is Periodic Table I.
b, II b, III b, VIII a group element, ε is at least one selected from O, B, C, N, F and S, and γ is V, Ta, Nb, Cr, Mo,
At least one selected from the group consisting of W, Sn, and Pb, u and v are numbers from 0 to 1 and w and x
Is a number greater than 0 and less than or equal to 1 and y is a number greater than or equal to 1 and less than or equal to 4]. 2. A selected from the IIa and IIIa groups of the periodic table.
One element α, one element β, V, T selected from the elements including the same elements as the element α in Group IIa and IIIa of the periodic table
at least one element γ selected from the group consisting of a, Nb, Cr, Mo, W, Sn and Pb, and Ib, IIb, IIIb of the periodic table,
VIII. Production of a superconducting material consisting of a composite oxide, characterized by sintering a mixture of oxides, carbonates, sulfates or powders of sulfates with one element δ selected from Group VIIIa elements Method. 3. A selected from the IIa and IIIa groups of the periodic table.
One element α, one element β, V, T selected from the elements including the same elements as the element α in Group IIa and IIIa of the periodic table
at least one element γ selected from the group consisting of a, Nb, Cr, Mo, W, Sn and Pb, and Ib, IIb, IIIb of the periodic table,
A superconducting thin film characterized by forming a thin film of a perovskite-type oxide or a pseudo-perovskite-type oxide by performing physical vapor deposition using an oxide containing one element δ selected from Group VIII a elements as a target. Manufacturing method.