JP2005056741A - Thin film superconductive wire rod and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a practical thin film superconductive wire rod provided with a superconductive layer superior in Jc-value on the substrate of a lengthy tape-like shape. <P>SOLUTION: This is the thin film superconductive wire rod in which the base layer provided with a metal substrate, and a current-carrying layer provided with a superconductive layer are provided. An intra-surface orientation property in the region of this layer contacting this current-carrying layer is in a range of 5° to 14°, the c-axis inclination of a region of the base layer contacting this current-carrying layer is in a range of 0° to 5°, and the intra-surface orientation property of this current-carrying layer is in a range of 0° to 12°. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a thin film superconducting wire. More specifically, the present invention relates to a thin film superconducting wire used for superconducting equipment such as wires, cables and magnets, and high magnetic field generators such as NMR, nuclear fusion, accelerators and linear.

  Moreover, this invention relates to the manufacturing method of said thin film superconducting wire.

  Since the discovery of high-temperature superconductors, the development of high-temperature superconducting wires aimed at power devices such as cables, current limiters, and magnets has been vigorously conducted by research institutions around the world. We are developing high-temperature superconducting thin film wires using pulsed laser deposition (PLD) or metal organic deposition (MOD), which is one of the vapor phase methods. , Are working on increasing the length and increasing the critical current density.

In general, a high-temperature superconducting thin film epitaxially formed on a single crystal substrate has high-quality crystallinity, and its critical current density (Jc) is a Bi-based Ag sheath that is currently being developed at a rapid pace. compared with wire, two orders of magnitude higher value under liquid nitrogen (77.3 K), shows a ^{10 5 ~10 6 a / cm 2} .

When considering wire forming by a vapor phase method or a MOD method, it is necessary to form a thin film on a long tape-shaped substrate. A tape-shaped single-crystal substrate is not available, and it is necessary to use a metal tape or the like excellent in handling as a substrate in consideration of equipment application. However, since the metal tape is polycrystalline and it is difficult to perform epitaxial growth even if a thin film is formed thereon, the superconducting characteristics also have a low Jc of about 10 ⁴ A / cm ² .

  Thus, metals are generally used for substrates for thin film superconducting wires, which are usually polycrystalline. When an oxide thin film is formed on such a substrate by a laser vapor deposition method, a reactive vapor deposition method, a MOD method, or the like, the oxide thin film is often polycrystalline or amorphous having a random orientation. Also, even when the oxide thin film has a natural orientation, the crystal of the oxide thin film orients a specific crystal axis in a direction perpendicular to the substrate surface, while the axis in the direction parallel to the substrate surface is rarely oriented. Absent.

In addition, when an oxide superconducting layer is formed on a polycrystalline substrate such as MgO, SrTiO ₃ , or ZrO ₂ , an oxide superconducting layer having a uniform crystal plane orientation is often formed. Here, since the superconducting current is blocked by the crystal agglomerates, the oxide superconducting layer formed on the polycrystal by the conventional technique has a problem that it cannot exhibit sufficient superconducting characteristics.

  In order to overcome such problems, research institutes around the world are currently conducting research and development to form a superconducting layer on a long tape-shaped substrate to obtain a practical thin film superconducting wire. For example, a technique combining laser vapor deposition and ion beam irradiation has been reported (for example, see Non-Patent Document 1).

In this technique, an yttria-stabilized zirconia (YSZ) intermediate layer is formed on a Hastelloy C276 tape in a laser vapor deposition apparatus with ion beam irradiation. In this technique, while performing deposition by irradiating a YSZ target with a laser beam, an attempt is made to forcibly order the grown crystal by irradiating a Kr ⁺ ion beam from a predetermined direction. . It has been reported that a YSZ layer in which crystal axes are ordered in a plane parallel to the substrate is formed by this technique. However, even with this technique, a sufficiently practical thin film superconducting wire has not yet been obtained by a device that only performs ion beam irradiation.

  In addition, a technique for forming an intermediate layer and a superconducting layer on a long tape-shaped metal substrate, wherein the intermediate layer is formed by a substrate inclined deposition method (ISD method). Has been reported (for example, see Patent Document 1 and Non-Patent Document 2).

  However, the intermediate layer obtained by the above ISD method tends to have poor crystallinity, the in-plane orientation tends to be large as about 18 ° to 25 °, and the c-axis inclination is about 5 ° to 7 °. There is a big tendency. The reason why the intermediate layer has such a tendency is that it is difficult to reduce the in-plane orientation of the intermediate layer in order to form the intermediate layer by tilting the substrate in the ISD method.

  Further, the intermediate layer obtained by the above ISD method tends to have a large surface roughness of an intermediate layer such as YSZ of 100 nm or more. The reason why the surface roughness of the intermediate layer is increased in this way is that when the intermediate layer is formed by the ISD method using the laser vapor deposition method, the film formation speed is high, but dense crystal growth is difficult.

Furthermore, the intermediate layer obtained by the above ISD method tends to have many voids formed on the surface of the intermediate layer. The reason why so many voids are formed on the surface of the intermediate layer is that when the intermediate layer is formed by the laser vapor deposition method, the film formation rate is high, but it is difficult to perform precise crystal growth. For this reason, it is necessary to fill a void by forming a cap layer such as CeO ₂ thereon.

For the reasons described above, even if a superconducting layer is formed on a long tape-shaped substrate by a conventionally known ISD method, the Jc level is about 0.1 to 0.5 MA / cm ² (77K, 0T). A sufficiently practical thin film superconducting wire has not been obtained yet.

Further, a YBCO (YBa ₂ Cu ₃ O _7-γ ) superconductor is formed on a long tape-shaped metal substrate obtained by a method called an oriented metal substrate method, also called RABiTS® (Rolling-assisted Biaxially Textured Substrates method). A technique for forming a layer has been reported (for example, see Non-Patent Document 3).
However, in this technique, Jc of the YBCO superconducting layer formed by the pulse laser deposition method on the metal substrate obtained by the oriented metal substrate method is pulse laser deposition on the STO ((100) SrTiO ₃ ) single crystal substrate. A sufficiently practical thin film superconducting wire has not yet been obtained, which is significantly lower than the Jc of the YBCO superconducting layer formed by the method.
JP-A-2-291626 Yasuhiro Iijima and 5 others, “Continuous synthesis of YBCO thin film tape oriented in the substrate plane”, Proceedings of the 49th Low Temperature Engineering and Superconductivity Society, Spring 1993, p. 134 Kozo Fujino, 6 others, “Development of high-temperature superconducting thin film wire by ISD method”, SEI Technical Review, Sumitomo Electric Industries, Ltd., September 1999, No. 155, p. 131-135 B. W. Kang, 6 others, “Comparative study of thickness dependence of critical current density of YBa2Cu3O7-δon (100) SrTiO3 and on rolling-assisted biaxially textured substrates”, J. Am. Mater. Res. July 2002, Vol. 17, No. 7, p. 1750-1757

  Based on the above situation, an object of the present invention is to provide a practical thin film superconducting wire having a superconducting layer having an excellent Jc value on a long tape-shaped substrate.

  Another object of the present invention is to provide an efficient and simple method for producing a thin film superconducting wire that makes it possible to form a superconducting layer having an excellent Jc value on a long tape-shaped substrate. is there.

  In order to solve the above-mentioned problems, the present inventor forms a cap layer and a superconducting layer on a long tape-shaped substrate and / or intermediate layer in which in-plane orientation and c-axis inclination are in a certain range. A thin-film superconducting wire was prototyped and evaluated using a long tape-shaped substrate and / or an intermediate layer having various in-plane orientations and c-axis inclinations.

  As a result, the inventor has in-plane orientation in the range of 5 ° to 14 ° and c-axis inclination in the range of 0 ° to 5 ° on the long tape-shaped substrate and / or intermediate layer. By forming a cap layer having an in-plane orientation of 0 ° to 12 ° and further forming a superconducting layer having an in-plane orientation of 0 ° to 12 ° on the cap layer, the superconducting layer has an excellent Jc value. It has been found that a thin film superconducting wire having the following can be obtained.

  In addition, the inventor has obtained a long tape-shaped metal substrate having an in-plane orientation in a range of 5 ° to 14 ° and a c-axis inclination in a range of 0 ° to 5 ° by an oriented metal substrate method. It was found that it can be easily obtained.

  Furthermore, when the present inventor forms an intermediate layer on the metal substrate obtained by the oriented metal substrate method by the RF sputtering method and / or the E-beam method, the in-plane orientation is more easily in the range of 5 ° to 14 °. It was found that an intermediate layer having a c-axis inclination in the range of 0 ° to 5 ° can be obtained.

  The inventor can easily achieve in-plane orientation of 10 ° to 14 ° by forming an intermediate layer on a long tape-shaped substrate by an ion beam assisted deposition method (ion beam assisted film forming method). It was found that an intermediate layer having a c-axis inclination in the range of 0 ° to 5 ° can be formed.

  In addition, the present inventor has determined that the in-plane orientation is in the range of 5 ° to 14 ° and the c-axis inclination is in the range of 0 ° to 5 °, and the PLD method is used on the metal substrate and / or the intermediate layer. A cap layer having an in-plane orientation in the range of 0 ° to 12 ° can be easily formed by one or more methods selected from the group consisting of (pulsed laser deposition), RF sputtering, and E-beam methods. I found out that I can do it.

  Further, the present inventor can easily perform the in-plane orientation in the range of 5 ° to 14 ° and the c-axis inclination in the range of 0 ° to 5 ° on the metal substrate and / or the intermediate layer. It has been found that a superconducting layer having in-plane orientation in the range of 0 ° to 12 ° can be formed.

  Then, the inventor of the present invention can easily achieve in-plane orientation of 0 ° to 12 ° by the PLD method and / or the MOD method as long as the in-plane orientation is on the cap layer in the range of 0 ° to 12 °. The present inventors have found that a superconducting layer in the range can be formed and completed the present invention.

  That is, the thin film superconducting wire of the present invention is a thin film superconducting wire comprising a base layer comprising a metal substrate and a conducting layer comprising a superconducting layer, and the in-plane orientation of the region in contact with the conducting layer of this base layer is 5 The c-axis inclination of the region in contact with the energization layer in the base layer is in the range of 0 ° to 5 °, and the in-plane orientation of the energization layer is in the range of 0 ° to 12 °. It is a thin film superconducting wire.

  Here, the surface smoothness of a region in contact with the energization layer in the base layer may be in the range of 0 nm to 100 nm. The base layer may include a metal substrate formed by an oriented metal substrate method. Further, the base layer may include a metal substrate and an intermediate layer formed by an ion beam assisted deposition method.

Here, this intermediate layer is made of a ZrO ₂ oxide, a Y—Zr—O oxide, a Gd—Zr—O oxide and a Re ₂ O ₃ oxide (Re represents Y and a rare earth element). You may contain 1 or more types chosen from a group.

  The energization layer includes a superconducting layer and a cap layer. The cap layer and the base layer are in contact with each other, and the c-axis inclination of the region in contact with the cap layer in the base layer is in the range of 0 ° to 5 °. The in-plane orientation of the layer may be in the range of 0 ° to 12 °, and the in-plane orientation of the superconducting layer may be in the range of 0 ° to 12 °.

Furthermore, the superconducting layer _{YB 2 C 3 O 7-x} , HoB 2 C 3 O 7-x, ErB 2 C 3 O 7-x, EuB 2 C 3 O 7-x, SmB 2 C 3 O 7-x And one or more selected from the group consisting of GdB ₂ C ₃ O _7-x and NdB ₂ C ₃ O _7-x .

The cap layer contains at least one selected from the group consisting of CeO ₂ oxides, BZO oxides, MgO oxides, and Re ₂ O ₃ oxides (Re represents Y and rare earth elements). May be.

  The cap layer is formed by one or more methods selected from the group consisting of the PLD method, the sputtering method, and the E-beam method, and the superconducting layer may be formed by the PLD method and / or the MOD method.

Furthermore, Jc of the superconducting layer is 77K, it is preferably in the range of 1MA / cm ² ~3MA / cm ² under the conditions of 0T.

  Further, the method for producing a thin film superconducting wire of the present invention is a method for producing a thin film superconducting wire comprising a base layer comprising a metal substrate and an energization layer, comprising the metal substrate and in-plane orientation of a region in contact with the energization layer. The step of forming the base layer, and the in-plane orientation is 0 ° to 0 °, the c-axis inclination of the region in contact with the current-carrying layer in the base layer is in the range of 0 ° to 5 °. Forming a current-carrying layer in a range of 12 °, and a method for producing a thin film superconducting wire.

  Here, the step of forming the base layer may include a step of forming a base layer in which the surface smoothness of the region in contact with the energization layer is in the range of 0 nm to 100 nm. Further, the step of forming the base layer may include a step of forming the metal substrate by an oriented metal substrate method.

  Further, the step of forming the base layer may include a step of forming a metal substrate by an oriented metal substrate method and a step of forming an intermediate layer on the metal substrate by a sputtering method and / or an E-beam method. Alternatively, the step of forming the base layer may include a step of forming an intermediate layer on the metal substrate by an ion beam assisted deposition method.

  The step of forming the intermediate layer includes the step of forming an intermediate layer containing a metal oxide having one or more crystal structures selected from the group consisting of a pyrochlore type, a meteorite type, a rock salt type, and a perovskite type. May be included.

Further, the step of forming this intermediate layer includes ZrO ₂ -based oxide, Y-Zr-O-based oxide, Gd-Zr-O-based oxide and Re ₂ O ₃ -based oxide (Re represents Y and rare earth elements). A step of forming an intermediate layer containing one or more selected from the group consisting of:

  Furthermore, the step of forming the current-carrying layer includes the step of forming the cap layer having an in-plane orientation in the range of 0 ° to 12 ° on the base layer, and the in-plane orientation of 0 ° to 12 on the cap layer. Forming this superconducting layer in the range of 0 °.

And the step of forming this superconducting layer includes YB ₂ C ₃ O _7-x , HoB ₂ C ₃ O _7-x , ErB ₂ C ₃ O _7-x , EuB ₂ C ₃ O _7-x , SmB ₂ C A step of forming a superconducting layer containing one or more selected from the group consisting of ₃ O _7-x , GdB ₂ C ₃ O _7-x and NdB ₂ C ₃ O _7-x may be included.

  The step of forming the cap layer includes the step of forming a cap layer containing a metal oxide having one or more crystal structures selected from the group consisting of a pyrochlore type, a meteorite type, a rock salt type, and a perovskite type. May be included.

The step of forming the cap layer is selected from the group consisting of CeO ₂ oxides, BZO oxides, MgO oxides and Re ₂ O ₃ oxides (Re represents Y and rare earth elements). A step of forming a cap layer containing one or more kinds may be included.

  Further, the step of forming the cap layer includes the step of forming the cap layer by one or more methods selected from the group consisting of the PLD method, the sputtering method, and the E-beam method, and the step of forming the superconducting layer includes: A step of forming a superconducting layer by a PLD method and / or a MOD method may be included.

  From the above results, in the thin film superconducting wire of the present invention, the in-plane orientation of the base layer made of a composite comprising a tape-like metal substrate / intermediate layer or the base layer made of the tape-like metal substrate itself is 14 ° or less. Since it is highly oriented and the c-axis inclination is as small as 5 ° or less, the current-carrying layer including the cap layer and superconducting layer thereon can be epitaxially grown in a highly oriented state, so the Jc of the superconducting layer becomes high.

  That is, the thin film superconducting wire of the present invention is a practical thin film superconducting wire having a superconducting layer having an excellent Jc value on a long tape-shaped substrate.

  Moreover, the method for producing a thin film superconducting wire of the present invention is an efficient and simple method for producing a thin film superconducting wire that makes it possible to form a superconducting layer having an excellent Jc value on a long tape-shaped substrate. .

  Hereinafter, the present invention will be described in more detail with reference to embodiments.

<Thin film superconducting wire>
The thin film superconducting wire of the present invention is a thin film superconducting wire comprising a base layer comprising a metal substrate and a conducting layer comprising a superconducting layer, and the in-plane orientation of the region in contact with the conducting layer in the base layer is in a specific range. In the base layer, the c-axis inclination of the region in contact with the energization layer is in a specific range, and the in-plane orientation of the energization layer is a thin film superconducting wire in the range of 0 ° to 12 °.

Here, the in-plane orientation of the region in contact with the current-carrying layer in this base layer tends to be 5 ° or more, and in particular, tends to be 8 ° or more due to manufacturing restrictions. The in-plane orientation is preferably 14 ° or less, and more preferably 10 ° or less. If a superconducting layer is formed when this in-plane orientation is 14 ° or less, it is possible to obtain a large Jc of about 4 to 5 MA / cm ² as in the superconducting layer grown on a single crystal substrate. Become. On the other hand, when this in-plane orientation exceeds 14 °, the connection between crystals deteriorates, and the in-plane orientation of the superconducting layer grown thereon tends to increase.

  Of course, the c-axis inclination of the region in contact with the energization layer in this base layer is desirably 0 ° or more, but tends to be 1 to 2 ° due to manufacturing restrictions. The c-axis inclination is preferably 5 ° or less, and more preferably 1 ° or less. If this c-axis inclination is 5 ° or less, formation of a superconducting layer having the same degree of Jc as that on a single crystal substrate can be expected, but if this c-axis inclination exceeds 5 °, a superconducting layer that grows thereon There is also a tendency that the c-axis inclination of increases.

Further, the in-plane orientation of the current-carrying layer is naturally desirably 0 ° or more, but tends to be 5 ° or more due to manufacturing restrictions. Further, the in-plane orientation is preferably 12 ° or less, and more preferably 8 ° or less. When this in-plane orientation is 12 ° or less, there is a tendency to form a superconducting layer having a Jc as large as 4 to 5 MA / cm ^{2. When} this in-plane orientation exceeds 12 °, There is a tendency that the connection between crystals decreases and the Jc of the formed superconducting layer decreases to 1 MA / cm ² or less.

  As described above, the thin film superconducting wire of the present invention has a highly oriented in-plane orientation of a base layer composed of a composite having a tape-shaped metal substrate / intermediate layer or a base layer composed of a tape-shaped metal substrate itself, being 14 ° or less. Therefore, since the conductive layer including the cap layer and the superconducting layer thereon can be epitaxially grown in a highly oriented state, the Jc of the superconducting layer is increased.

  In addition, since the thin-film superconducting wire of the present invention has a small c-axis inclination of 5 ° or less as described above, the in-plane orientation of the base layer is 14 ° or less and high orientation. The effect further increases Jc of the superconducting layer.

  Here, of the base layer, the surface smoothness of the region in contact with the current-carrying layer is naturally 0 nm or more, and tends to be 50 nm or more due to manufacturing restrictions. The surface smoothness is preferably 100 nm or less, and more preferably 80 nm or less. When the surface smoothness is 100 nm or less, a large Jc tends to be obtained even when the formed superconducting layer is 1 micron or less. When the surface smoothness exceeds 100 nm, the formed superconducting layer There is a tendency that sufficient Jc cannot be obtained unless the film is grown to a thickness of about 1 to 2 microns.

  Thus, the surface smoothness of the region in contact with the current-carrying layer in the base layer made of the composite having the tape-like metal substrate / intermediate layer or the region in contact with the current-carrying layer in the base layer made of the tape-like metal substrate itself is 100 nm. When it is below, there is an advantage that the epitaxial growth is facilitated in a state in which the conductive layer including the cap layer and the superconducting layer thereon is highly oriented. As a result, the surface smoothness of the superconducting layer provided in the conducting layer is improved, and the Jc of the superconducting layer is further increased.

  The base layer may include a metal substrate formed by an oriented metal substrate method. Further, the base layer may include a metal substrate and an intermediate layer formed by an ion beam assisted deposition method.

  Thus, among the base layer composed of a composite having a tape-shaped metal substrate / intermediate layer or the base layer composed of the tape-shaped metal substrate itself, the metal substrate is formed by the oriented metal substrate method, or the intermediate layer is When formed by ion beam assisted deposition, the superconducting layer provided on the current-carrying layer formed thereon becomes dense, element diffusion from the metal substrate to the superconducting layer is suppressed, and the high Jc of the superconducting layer is achieved. There is an advantage that becomes possible.

Here, the intermediate layer is composed of a ZrO ₂ oxide, a Y—Zr—O oxide, a Gd—Zr—O oxide and a Re ₂ O ₃ oxide (Re represents Y and a rare earth element). You may contain 1 or more types chosen from the group which consists of.

Thus, when the material of the intermediate layer is a ZrO ₂ or A-Zr—O (A = Y, Gd, etc.) type oxide material, high orientation (in-plane) is achieved by sputtering, PLD, or E-beam. (The orientation value is small) and a dense film is possible, and there is an advantage that there is little reaction with the superconducting layer.

  The energization layer includes a superconducting layer and a cap layer. The cap layer and the base layer are in contact with each other, and the c-axis inclination of a region of the base layer in contact with the cap layer is within a specific range. The in-plane orientation may be in a specific range, and the in-plane orientation of the superconducting layer may be in a specific range.

  Thus, by providing a cap layer in addition to the superconducting layer in the conducting layer, there is an advantage that the lattice strain between the intermediate layer and the superconducting layer can be relaxed.

  Here, the c-axis inclination of the region in contact with the cap layer in the base layer is naturally 0 ° or more, and tends to be 1 to 2 ° due to manufacturing restrictions. The c-axis inclination is preferably 5 ° or less, and more preferably 1 ° or less. When the c-axis inclination is 5 ° or less, a high Jc tends to be obtained in the formed superconducting layer. When the c-axis inclination exceeds 5 °, the Jc of the formed superconducting layer tends to be low. There is.

  Further, the in-plane orientation of the cap layer is naturally 0 ° or more, and tends to be 10 ° or more due to manufacturing restrictions. Further, the in-plane orientation is preferably 12 ° or less, and more preferably 8 ° or less. When this in-plane orientation is 12 ° or less, a high Jc tends to be obtained in the formed superconducting layer. When this in-plane orientation exceeds 12 °, the Jc of the formed superconducting layer is low. Tend to be.

  Furthermore, the in-plane orientation of the superconducting layer is naturally 0 ° or more, and tends to be 8 ° or more due to manufacturing restrictions. Further, the in-plane orientation is preferably 12 ° or less, and more preferably 8 ° or less. When this in-plane orientation is 12 ° or less, a superconducting layer having a high Jc comparable to that of the superconducting film on the single crystal substrate tends to be formed. When this in-plane orientation exceeds 12 °, There exists a tendency for Jc of the formed superconducting layer to become low.

Furthermore, the superconducting layer _{YB 2 C 3 O 7-x} , HoB 2 C 3 O 7-x, ErB 2 C 3 O 7-x, EuB 2 C 3 O 7-x, SmB 2 C 3 O 7-x It is preferable to contain 1 or more types selected from the group consisting of GdB ₂ C ₃ O _7-x and NdB ₂ C ₃ O _7-x .

Thus, when the superconducting layer is made of a material containing A ₁ B ₂ C ₃ O _7-x (A = Y, Ho, Er, Eu, etc.), the Tc of the superconducting layer becomes high, and the PLD method and This is because the superconducting layer having a high Jc can be easily crystallized by the MOD method or the like.

The cap layer contains at least one selected from the group consisting of CeO ₂ oxides, BZO oxides, MgO oxides, and Re ₂ O ₃ oxides (Re represents Y and rare earth elements). It is preferable to do.

Thus, when the material of the cap layer is an oxide material such as CeO ₂ , BZO, MgO, or Re ₂ O ₃ (Re represents Y and a rare earth element), the lattice between the ReBCO-based superconducting layer is used. This is because the strain is small, and the cap layer has an action of relaxing the lattice strain between the intermediate layer and the superconducting layer, which is preferable in obtaining a high Jc superconducting layer.

  The cap layer is formed by one or more methods selected from the group consisting of the PLD method, the sputtering method, and the E-beam method, and the superconducting layer may be formed by the PLD method and / or the MOD method.

  As described above, particularly when the cap layer is manufactured by the sputtering method and the superconducting layer is manufactured by the PLD method, both the cap layer and the superconducting layer become dense films and have excellent surface smoothness.

Furthermore, Jc of the superconducting layer is 77K, is preferably 1 MA / cm ² or more under the condition of 0T, and more preferably, especially 2 MA / cm ² or more. Also, Jc of this superconducting layer tends to be ³ MA / cm ² or less due to manufacturing restrictions. If this Jc is too small, there is a tendency that the conditions for practical use are not satisfied. If this Jc is too large, the heat generated at the end is large at the time of energization, and if the stable Ag or the like is not deposited thickly, the Jc is stable. Tend to not flow.

<Manufacturing method of thin film superconducting wire>
FIG. 1 is a flowchart showing an outline of a method for producing a thin film superconducting wire.

  The thin film superconducting wire manufacturing method of the present invention is a manufacturing method of the above-mentioned thin film superconducting wire comprising a base layer including a metal substrate and a current-carrying layer, as shown in FIG. The in-plane orientation of the region in contact with the electrode is in a specific range, and the c-axis inclination of the region in contact with the current-carrying layer in the base layer is in a specific range, and the in-plane orientation is specified in the step of forming the base layer (S101) Forming a current-carrying layer in the range of (S103). The method for manufacturing a thin film superconducting wire.

  Such a method for producing a thin film superconducting wire of the present invention has an advantage that the thin film superconducting wire of the present invention can be produced efficiently and simply.

  The detailed description of the method of manufacturing the thin film superconducting wire of the present invention is the same as the detailed description of the thin film superconducting wire of the present invention, and since it is duplicated, it will be omitted, but hereinafter the PLD method, ISD method, ion beam assist The vapor deposition method and the sputtering method will be described.

  Here, for reference, a schematic diagram of film formation by the PLD method and the ISD method is shown in FIG. In a normal PLD method, an intermediate layer or a superconducting material sintered target is irradiated with an excimer laser to form a plasma in vacuum, and a film is deposited on a substrate disposed oppositely.

  Here, in the PLD method, as shown in FIG. 2, the substrate 29 used in the PLD method is tilted in parallel with the sintered target 21. Then, a plasma 25 generated by irradiation with the laser beam 23 is deposited on the substrate 29 to form a thin film.

  The PLD method is a method suitable for a mass production process because the film forming speed is several tens to several hundred times faster than other thin film forming processes such as a sputtering method and a molecular beam epitaxy method. Film formation on the tape-shaped substrate 29 can be easily performed by moving the substrate 29 in a direction perpendicular to the paper surface in FIG.

  When an oxide thin film is formed by a conventionally known PLD method or the like, the oxide thin film is often polycrystalline or amorphous having a random orientation. Also, even when the oxide thin film has a natural orientation, the crystal of the oxide thin film orients a specific crystal axis in a direction perpendicular to the substrate surface, while the axis in the direction parallel to the substrate surface is rarely oriented. Absent.

  However, in the method of manufacturing a superconducting thin film wire according to the present invention, as described above, by adjusting the in-plane orientation and c-axis inclination of the metal substrate, the intermediate layer, the cap layer, etc. It became possible to form a superconducting layer with small orientation and c-axis inclination and excellent Jc value.

  Here, in the ISD method, as shown in FIG. 2, the substrate 27 used for the ISD method is inclined at a certain angle with respect to the sintered target 21. By adopting such a geometric arrangement, there are two crystal axes, that is, a crystal axis to be oriented perpendicular to the substrate surface and a crystal axis to be oriented with respect to the flight direction of the plasma 25 generated by the laser beam 23 irradiation. Axial orientation occurs. For this reason, it is possible to form a thin film having a structure which is polycrystalline but is perpendicular to the substrate surface and preferentially oriented within the substrate surface.

  The feature of the ISD method is that such a thin film close to a single crystal can be formed only by the geometrical arrangement of the substrate, and the apparatus is simple and very advantageous even considering a mass production process. However, the ISD method has a problem that the in-plane orientation of the intermediate layer and the inclination of the c-axis tend to increase.

  FIG. 3 is a schematic diagram of film formation by ion beam assisted deposition.

In the ion beam assisted deposition method, a thin film such as an intermediate layer is formed on a metal substrate 31 in a laser deposition apparatus that performs ion beam irradiation as shown in FIG. In this method, while performing deposition by irradiating the sintered target 32 with the laser beam 33, the grown crystal is forcibly ordered by irradiating the ion beam 34 such as Kr ⁺ from a predetermined direction. Try to have it. By this method, it is possible to form a thin film such as an intermediate layer in which the crystal axes are ordered in a plane parallel to the substrate as compared with the normal PLD method.

  In the method for manufacturing a superconducting thin film wire of the present invention, a thin film such as an intermediate layer having an in-plane orientation and a c-axis inclination smaller than that of a normal PLD method is formed by using an ion beam assisted vapor deposition method as one embodiment. It is possible to do.

  Sputtering uses the phenomenon that atoms or molecules are scattered from the target surface by vaporization or collision and adhere to the nearby object surface by heating or ion bombardment of a sintered target in a low-pressure gas. And forming a thin film on the substrate. Since the sputtering method is a well-known technique, a detailed description thereof is omitted.

  Here, the manufacturing method of the superconducting thin film wire of the present invention is not a simple collection of these PLD method, ISD method, ion beam assisted vapor deposition method, sputtering method and the like, but a multilayer structure (intermediate layer-cap layer-superconductivity). Layer), which is different from conventional methods in providing an optimum method for optimizing crystal growth in each layer, and by adopting these manufacturing methods, in-plane orientation and c-axis tilt angle are provided. For example, the parameter for increasing the Jc flowing in the superconducting layer has an excellent characteristic effect that leads to a preferable direction from the intermediate layer to the cap layer and from the cap layer to the superconducting layer.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Comparative Example 1>
In this comparative example, a thin film superconducting wire using a part of the conventional ISD method was manufactured.

  FIG. 4 is a schematic view of a method of manufacturing a thin film superconducting wire partly using a conventional ISD method.

  First, on a metal substrate 413 made of hastelloy (Ni-based alloy) tape, a plasma beam 405 is generated by irradiating a sintered target 401 with a laser beam 403 using an ISD method which is a modification of the PLD method. A micron YSZ intermediate layer 411 was formed. The in-plane orientation of the formed YSZ intermediate layer 411 was 18 °, the c-axis inclination was 6 °, and the surface smoothness was about 100 nm.

Next, a film was formed on the YSZ intermediate layer 411 by the PLD method so that the CeO ₂ cap layer 409 had a thickness of 0.1 μm. Unevenness remained on the surface of the formed YSZ intermediate layer 411, and the surface smoothness was about 80 nm.

Subsequently, a HoBCO superconducting layer 407 was formed on the CeO ₂ cap layer 409 by a PLD method so as to have a film thickness of 1.8 microns. Jc of the formed HoBCO superconducting layer 407 was 0.18 MA / cm ² (77K, 0T).

<Example 1>
In this example, an example of the method for producing the thin film superconducting wire of the present invention was performed.

  FIG. 5 is a schematic view of an example of a method for producing a thin film superconducting wire of the present invention.

  First, an ion beam assisted deposition method is used to irradiate a sintered target 501 with an E beam 503 on a metal substrate 513 made of hastelloy (Ni-based alloy) tape to generate a plasma 505, and a YSZ intermediate film having a thickness of 2 microns. Layer 511 was formed. The formed YSZ intermediate layer 511 had an in-plane orientation of 14 °, a c-axis inclination of 1 °, and a surface smoothness of about 20 nm.

Next, a CeO ₂ cap layer 509 was formed on the YSZ intermediate layer 511 so as to have a film thickness of 0.04 microns using the PLD method. The surface of the formed CeO ₂ cap layer 509 had almost no unevenness, and the surface smoothness was about 15 nm.

Subsequently, a HoBCO film 507 was formed on the CeO ₂ cap layer 509 so as to have a film thickness of 1.0 μm by using the PLD method. Jc of the formed HoBCO film 507 was 1.1 MA / cm ² (77K, 0T).

<Example 2>
In this example, an example of the method for producing the thin film superconducting wire of the present invention was performed.

  First, a YSZ intermediate layer having a thickness of 1.5 microns was formed on a metal substrate made of an incoloy (Fe-based alloy) tape by using an ion beam assisted deposition method. The in-plane orientation of the formed YSZ intermediate layer was 12 °, the c-axis inclination was 1 °, and the surface smoothness was about 25 nm.

Next, a Ho ₂ O ₃ cap layer was formed on the YSZ intermediate layer so as to have a film thickness of 0.1 μm using the PLD method. The surface of the formed Ho ₂ O ₃ cap layer had almost no unevenness, and the surface smoothness was about 15 nm.

Subsequently, a HoBCO superconducting layer was formed on the Ho ₂ O ₃ cap layer by a PLD method so as to have a film thickness of 1.2 microns. Jc of the formed HoBCO superconducting layer was 1.1 MA / cm ² (77K, 0T).

<Example 3>
In this example, an example of the method for producing the thin film superconducting wire of the present invention was performed.

  First, a 2 micron YSZ film was formed on a Ni—Fe alloy tape (aligned metal substrate) having an in-plane orientation of 11 ° by RF sputtering. The in-plane orientation of the formed YSZ film was 10 °, the c-axis inclination was 0.5 °, and the surface smoothness was about 30 nm.

Next, a film was formed on the YSZ film by a PLD method so as to have a film thickness of 0.05 microns using CeO ₂ as a cap layer. The surface of the formed CeO ₂ cap layer had almost no unevenness, and the surface smoothness was about 15 nm.

Subsequently, a HoBCO superconducting layer was formed on the CeO ₂ cap layer so as to have a film thickness of 1.6 microns by using the PLD method. The formed HoBCO superconducting layer had Jc = 1.1 MA / cm ² (77K, 0T) and Ic = 176A (77K, 0T).

<Example 4>
In this example, an example of the method for producing the thin film superconducting wire of the present invention was performed.

First, a 0.1 μm-thick CeO ₂ film is formed on a metal substrate made of a Ni / SUS composite tape (composite-oriented metal substrate) having an in-plane orientation of 12 ° using an RF sputtering method, and then a PLD method. As a result, a YSZ intermediate layer having a thickness of 1 micron was formed. The in-plane orientation of the formed YSZ intermediate layer was 10 °, the c-axis inclination was 0.3 °, and the surface smoothness was about 20 nm.

Next, a CeO ₂ cap layer was formed on the YSZ intermediate layer so as to have a film thickness of 0.04 microns using the PLD method. The surface of the formed CeO ₂ cap layer had almost no unevenness, and the surface smoothness was about 9 nm.

Subsequently, a HoBCO superconducting layer was formed on the CeO ₂ cap layer so as to have a film thickness of 0.36 microns using the PLD method. Jc of the formed HoBCO superconducting layer was 2.2 MA / cm ² (77K, 0T).

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a flowchart which shows the outline of the manufacturing method of a thin film superconducting wire. It is the schematic of the film-forming by PLD method and ISD method. It is the schematic of the film-forming by an ion beam assist vapor deposition method. It is the schematic of the manufacturing method of the thin film superconducting wire which used some conventional ISD methods. It is the schematic of an example of the manufacturing method of the thin film superconducting wire of this invention.

Explanation of symbols

21, 32, 401, 501 Sintered target, 23, 33, 403 laser beam, 503 E beam, 25, 405, 505 plasma, 27, 29, 31 substrate, 34 ion beam, 407, 507 HoBCO superconducting layer, 409, 509 CeO ₂ cap layer, 411,511 YSZ intermediate layer, 413,513 metal substrate.

Claims (24)

  A thin film superconducting wire comprising a base layer comprising a metal substrate and a conducting layer comprising a superconducting layer, wherein the in-plane orientation of the region contacting the conducting layer in the base layer is in the range of 5 ° to 14 °; A thin-film superconducting wire in which the c-axis inclination of a region in contact with the energization layer in the base layer is in the range of 0 ° to 5 °, and the in-plane orientation of the energization layer is in the range of 0 ° to 12 °.   2. The thin film superconducting wire according to claim 1, wherein a surface smoothness of a region in contact with the energization layer in the base layer is in a range of 0 nm to 100 nm.   The thin film superconducting wire according to claim 1, wherein the base layer includes the metal substrate formed by an oriented metal substrate method.   The thin film superconducting wire according to claim 1, wherein the base layer includes the metal substrate and an intermediate layer formed by an ion beam assisted vapor deposition method.   The thin film superconducting wire according to claim 1, wherein the intermediate layer contains a metal oxide having one or more crystal structures selected from the group consisting of a pyrochlore type, a meteorite type, a rock salt type, and a perovskite type. The intermediate layer contains ZrO ₂ based oxide, Y-ZrO-based oxide, one or more members selected from the group consisting of Gd-ZrO-based oxide and Re ₂ O ₃ based oxide, claim 1. The thin film superconducting wire according to 1.   The energization layer includes the superconducting layer and a cap layer, the cap layer and the base layer are in contact with each other, and a c-axis inclination of a region of the base layer in contact with the cap layer is in a range of 0 ° to 5 °. The thin film superconducting wire according to claim 1, wherein the in-plane orientation of the cap layer is in the range of 0 ° to 12 °, and the in-plane orientation of the superconducting layer is in the range of 0 ° to 12 °. The superconducting layer _{YB 2 C 3 O 7-x} , HoB 2 C 3 O 7-x, ErB 2 C 3 O 7-x, EuB 2 C 3 O 7-x, SmB 2 C 3 O 7-x, GdB containing ₂ C ₃ O _7-x and _{NdB 2 C 3 O 7-x} 1 or more selected from the group consisting of a thin film superconducting wire according to claim 7.   The thin film superconducting wire according to claim 7, wherein the cap layer contains a metal oxide having at least one crystal structure selected from the group consisting of a pyrochlore type, a meteorite type, a rock salt type, and a perovskite type. The cap layer contains one or more selected from the group consisting of CeO ₂ -based oxides, BZO-based oxides, MgO-based oxides, and Re ₂ O ₃ -based oxides (Re represents Y and rare earth elements). The thin film superconducting wire according to claim 7.   The cap layer is formed by at least one method selected from the group consisting of a PLD method, a sputtering method, and an E-beam method, and the superconducting layer is formed by a PLD method and / or a MOD method. Thin film superconducting wire described in 1. The Jc of the superconducting layer is 77K, the range of 1MA / cm ² ~3MA / cm ² under the conditions of 0T, thin film superconducting wire according to claim 7. A method for producing a thin film superconducting wire comprising a base layer comprising a metal substrate and an energization layer,
The in-plane orientation of the region in contact with the current-carrying layer is in the range of 5 ° to 14 °, and the c-axis inclination of the region in contact with the current-carrying layer in the base layer is in the range of 0 ° to 5 °. Forming a base layer in
Forming the current-carrying layer having in-plane orientation in the range of 0 ° to 12 °;
A method for producing a thin film superconducting wire.   The method for producing a thin film superconducting wire according to claim 13, wherein the step of forming the base layer includes the step of forming the base layer having a surface smoothness in a range of 0 nm to 100 nm in a region in contact with the energization layer.   The method of manufacturing a thin film superconducting wire according to claim 13, wherein the step of forming the base layer includes a step of forming the metal substrate by an oriented metal substrate method.   The step of forming the base layer includes the step of forming the metal substrate by an oriented metal substrate method, and an intermediate layer by one or more methods selected from the group consisting of a PLD method, a sputtering method, and an E-beam method on the metal substrate. Forming the thin film superconducting wire according to claim 13.   The method for producing a thin film superconducting wire according to claim 13, wherein the step of forming the base layer includes a step of forming an intermediate layer on the metal substrate by ion beam assisted vapor deposition.   The step of forming the intermediate layer includes the step of forming an intermediate layer containing a metal oxide having one or more crystal structures selected from the group consisting of a pyrochlore type, a meteorite type, a rock salt type, and a perovskite type. The manufacturing method of the thin film superconducting wire according to claim 16 or 17. The step of forming the intermediate layer includes a ZrO ₂ oxide, a Y—Zr—O oxide, a Gd—Zr—O oxide and a Re ₂ O ₃ oxide (Re represents Y and a rare earth element). The method for producing a thin film superconducting wire according to claim 16 or 17, comprising a step of forming an intermediate layer containing at least one selected from the group consisting of:   The step of forming the conductive layer includes the step of forming the cap layer having an in-plane orientation in the range of 0 ° to 12 ° on the base layer, and the in-plane orientation of 0 ° to 12 on the cap layer. Forming the superconducting layer in the range of °. The method of manufacturing a thin film superconducting wire according to claim 13. Forming the superconducting _{layer, YB 2 C 3 O 7-} x, HoB 2 C 3 O 7-x, ErB 2 C 3 O 7-x, EuB 2 C 3 O 7-x, SmB 2 C 3 O _7-x, comprising the step of forming the superconducting layer containing one or more members selected from the group consisting of GdB ₂ C ₃ O _7-x and _{NdB 2 C 3 O 7-x} , thin film according to claim 20 Manufacturing method of superconducting wire.   The step of forming the cap layer includes the step of forming the cap layer containing a metal oxide having one or more crystal structures selected from the group consisting of a pyrochlore type, a meteorite type, a rock salt type, and a perovskite type. The method for producing a thin film superconducting wire according to claim 20. The step of forming the cap layer is one selected from the group consisting of CeO ₂ oxides, BZO oxides, MgO oxides, and Re ₂ O ₃ oxides (Re represents Y and a rare earth element). The manufacturing method of the thin film superconducting wire according to claim 20, comprising the step of forming the cap layer containing the above.   The step of forming the cap layer includes the step of forming the cap layer by at least one method selected from the group consisting of a PLD method, a sputtering method, and an E-beam method, and the step of forming the superconducting layer includes the PLD method. 21. The method of manufacturing a thin film superconducting wire according to claim 20, further comprising the step of forming the superconducting layer by a MOD method.

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