JP2011090934A - Base material for superconductive thin film wiring material, manufacturing method thereof, and superconductive thin film wiring material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method by which degradation of superconductive characteristics can be suppressed and the superconductive thin film wiring material can be obtained at a superior yield rate, and productivity can be improved sufficiently, when manufacturing a lengthy superconductive thin film wiring material by continuously forming an intermediate layer on a lengthy orientation metal substrate at a single time of processing, and furthermore by continuously forming an oxide superconductor thin film. <P>SOLUTION: The manufacturing method of a base material for the superconductive thin film wiring material, wherein the intermediate layer is formed having a bi-axially oriented intermediate layer formed on an orientation face of a tape-shaped orientation metal substrate, has a metal substrate fabricating process in which a non-orientation metal tape of a prescribed length is arranged between mutually neighboring two orientation metal tapes of a plurality of orientation metal tapes with a prescribed length and connected so that the lengthy metal substrate is manufactured, and an intermediate layer forming process in which the intermediate layer is continuously formed on the surface of the lengthy metal substrate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a substrate for a superconducting thin film wire, a method for manufacturing the same, and a superconducting thin film wire, and in particular, a method for manufacturing a substrate for a superconducting thin film wire capable of forming a long intermediate layer by a single film formation, and the manufacturing method The present invention relates to a substrate for a superconducting thin film wire manufactured by the method described above and a superconducting thin film wire using the substrate for a superconducting thin film wire.

Since the discovery of high-temperature superconductors that have superconductivity at the temperature of liquid nitrogen, development of high-temperature superconducting wires aimed at application to power devices such as cables, current limiters, and magnets has been actively conducted. Among them, a thin film superconducting wire obtained by thinning an oxide superconductor such as RE ₁ Ba ₂ Cu ₃ O _7-δ (RE represents a rare earth element) has attracted attention. In such a thin film superconducting wire, in order to obtain a high temperature superconducting wire having excellent superconducting properties, it is necessary to form an oxide superconductor thin film with high orientation.

  Such a high-temperature superconducting wire generally produces a base material for a superconducting thin film wire by epitaxially growing an oxide thin film as an intermediate layer on a long oriented metal substrate having biaxial orientation. In addition, an oxide superconductor is epitaxially grown on the intermediate layer to form a superconducting layer (for example, Patent Document 1).

  The present applicant has also proposed a technique for improving the orientation and flatness of these oriented metal substrates by heat-treating a nickel layer formed on the substrate (Japanese Patent Application No. 2009-163513).

JP 2006-127847 A

  However, when a long superconducting thin film wire is produced by continuously forming an intermediate layer on such a long oriented metal substrate in a single process and further forming an oxide superconductor thin film continuously. However, the superconducting properties were lowered from the middle of the produced long superconducting thin film wire, and there was a problem that the yield as a product was lowered. In order to suppress this decrease in yield, it is necessary to stop the formation of the oxide superconductor thin film when the superconducting characteristics do not deteriorate even when a long oriented metal substrate is used. For this reason, there is a limit to the length of the substrate for the superconducting thin film wire, that is, the length of the intermediate layer formed continuously in one process, and it is difficult to sufficiently improve the productivity. It was.

  For this reason, when a superconducting thin film wire is manufactured by forming an intermediate layer continuously on a long oriented metal substrate by a single process and further forming an oxide superconducting thin film, suppression of superconducting characteristics is suppressed. Therefore, it has been desired to develop a production method capable of obtaining a superconducting thin film wire with a high yield and sufficiently improving the productivity.

  The present inventor considers that the above-described deterioration in superconducting characteristics may occur due to the deterioration of the orientation in the intermediate layer formed on the oriented metal substrate, and thus on the oriented metal substrate. The orientation rate in the formed intermediate layer, specifically (200) orientation rate, was measured.

  As a result, it can be seen that after a certain length of time has elapsed since the start of film formation of the intermediate layer, the orientation rate has suddenly decreased, and this decrease in orientation rate has led to a decrease in the superconducting properties of the superconducting thin film wire. Was confirmed.

  And when further experiment was conducted, when forming an intermediate layer on a long oriented metal substrate, a non-oriented metal tape such as SUS was inserted in the middle of the long oriented metal substrate, and the intermediate layer was formed once. In the case where the film is continuously formed by the treatment, on the oriented metal substrate following the non-oriented metal tape, the film formation of the intermediate layer in which the once lowered orientation rate is restored to the level at the start of film formation may be started. As a result, the present invention has been completed. Hereinafter, each claim will be described.

The invention described in claim 1
A method for producing a substrate for a superconducting thin film wire in which a biaxially oriented intermediate layer is formed on an orientation surface of a tape-like oriented metal substrate,
Metal substrate production for producing a long metal substrate by arranging and connecting a non-oriented metal tape of a predetermined length between two adjacent metal tapes of a plurality of aligned metal tapes of a predetermined length Process,
An intermediate layer forming step of continuously forming the intermediate layer on a surface of the long metal substrate.

  As described above, when a non-oriented metal tape such as SUS is arranged and connected in the middle of a long oriented metal tape, the orientation ratio once lowered is formed on the oriented metal tape following the non-oriented metal tape. The formation of the intermediate layer that has recovered to the level at the start of the film is started.

  For this reason, a long metal substrate is produced by arranging and connecting a non-oriented metal tape of a predetermined length between two adjacent metal tapes of a plurality of oriented metal tapes of a predetermined length. When the length of the oriented metal tape is set to an appropriate length and the intermediate layer is continuously formed on the metal substrate, a certain length is obtained. In the meantime, film formation is performed while maintaining a sufficient orientation rate, and thereafter, an intermediate layer having a pattern in which the orientation rate only slightly decreases is repeatedly formed on each oriented metal tape.

  For this reason, unlike the conventional manufacturing method, there is no limit in the length of the intermediate layer continuously formed by one process, and the productivity can be sufficiently improved.

  When a superconducting thin film wire is produced by forming an oxide superconductor thin film on such a long metal substrate, the superconducting thin film wire has high yield because the degradation of superconducting properties is suppressed on the oriented metal tape. Can get

  In the invention of this claim, the length of the oriented metal tape is the material of the oriented metal tape and the intermediate layer to be formed (if a plurality of intermediate layers are formed, the seed film layer which is the first layer). Depending on the material, etc., the orientation ratio of the intermediate layer is set to a length that can maintain a level above a certain level that does not impede practical use, and the length of the non-oriented metal tape depends on the material, etc. On the metal tape, the length is set to such a length that the film formation of the intermediate layer can be started after the orientation rate once lowered is restored to the level at the time of film formation start.

As a specific example, a long metal substrate is prepared using a Ni / Cu / SUS oriented metal tape as an oriented metal tape and SUS as a non-oriented metal tape, and a CeO ₂ / YSZ (yttria) is formed thereon. When the intermediate layer made of (stabilized zirconia) / CeO ₂ is formed, the length of the oriented metal tape is set to about 30 m, and the length of the non-oriented metal tape is set to about 5 m.

  In addition, the orientation rate in the invention of this claim is a (200) orientation rate, and is determined by the formula [I (200) / {I (200) + I (111)}] × 100 (%). Here, I (200) and I (111) are the X-ray diffraction peak intensities of the (200) plane and (111) plane of the intermediate layer (seed film), respectively.

  The level of orientation rate is preferably (200) orientation rate, preferably 80% or more, and more preferably 90% or more.

  In the invention of this claim, the oriented metal tape means a metal tape in which the constituent metal elements are biaxially oriented, and includes not only perfect biaxial orientation but also a substrate whose crystal axis deviation angle is 25 ° or less. It is. The orientation is preferably such that the <100> axis is perpendicular to the substrate surface and the <010> axis is oriented in the length direction of the substrate.

  Specifically, as the oriented metal tape, an orientation made of a metal made of a simple substance of Ni, Cu, Ag, W, V, Cr, Mo, Mn, Al and Fe or an alloy made of any combination of these metal elements. A metal tape, an oriented metal tape having a multilayer structure having SUS as a reinforcing material such as Ni / Cu / SUS, and the like are preferably used.

  As the non-oriented metal tape, a metal tape made of SUS such as SUS304 or SUS316L and having the same width and thickness as the oriented metal tape is preferably used.

  As the intermediate layer, a metal oxide having one or more metal elements having a pyrochlore type, fluorite type, rock salt type or perovskite type crystal structure is preferably used.

Specifically, for example, a single intermediate layer formed by epitaxial growth such as CeO ₂ or an intermediate layer composed of a plurality of layers of CeO ₂ / YSZ / CeO ₂ is preferably used. As a formation method, a known method such as a sputtering method, an EBD (electron beam evaporation) method, a PLD method, or thermal evaporation can be used.

The invention described in claim 2
After the intermediate layer forming step,
2. The production of a substrate for a superconducting thin film wire according to claim 1, further comprising a non-oriented metal tape removing step of cutting and removing the non-oriented metal tape together with an intermediate layer formed on the non-oriented metal tape. Is the method.

  In the invention of this claim, the non-oriented metal tape is cut and removed from the long substrate for the superconducting thin film wire in which the intermediate layer is formed on the long metal substrate made of the oriented metal tape and the non-oriented metal tape. Therefore, the superconducting thin film wire substrate after the removal becomes a plurality of superconducting thin film wire substrates in which an intermediate layer having a certain level of orientation rate is formed on the oriented metal tape. By forming an oxide superconductor thin film on the substrate for superconducting thin film wires thus obtained, a superconducting thin film wire having excellent superconducting properties can be obtained reliably, and a decrease in yield is suppressed. Can do.

The invention according to claim 3
A substrate for a superconducting thin film wire, which is manufactured by the method for manufacturing a substrate for a superconducting thin film wire according to claim 1.

  As described above, the substrate for a superconducting thin film wire in which an intermediate layer is continuously formed on a long metal substrate composed of an oriented metal tape and a non-oriented metal tape is an intermediate layer having a stable orientation rate on the oriented metal tape. Is a substrate formed efficiently. Then, by forming an oxide superconductor thin film using such a substrate for a superconducting thin film wire, a superconducting thin film wire having excellent superconducting characteristics can be provided with a high yield.

The invention according to claim 4
A substrate for a superconducting thin film wire, which is manufactured by the method for manufacturing a substrate for a superconducting thin film wire according to claim 2.

  The base material for a superconducting thin film wire according to the present invention is a base material for a superconducting thin film wire in which an intermediate layer having a certain level of orientation ratio is formed on an oriented metal tape, so that an oxide superconductor thin film is formed. In this case, it is possible to suppress a decrease in superconducting characteristics and to provide a superconducting thin film wire having excellent superconducting characteristics with a high yield.

The invention described in claim 5
5. The substrate for a superconducting thin film wire according to claim 4, wherein the (200) orientation ratio of the intermediate layer is 90% or more.

  The substrate for a superconducting thin film wire according to the present invention is a substrate for a superconducting thin film wire in which an intermediate layer having a large (200) orientation ratio of 90% or more is formed on an oriented metal tape. Therefore, a superconducting thin film wire having excellent superconducting characteristics can be provided with a high yield by forming an oxide superconductor thin film on the substrate for this superconducting thin film wire.

The invention described in claim 6
A superconducting thin film wire characterized in that a superconducting film made of an oxide superconductor is formed on an intermediate layer of the substrate for a superconducting thin film wire according to claim 4 or 5.

  Since the superconducting thin film wire according to the present invention is obtained by forming a superconducting film made of an oxide superconductor on an oriented metal tape on which an intermediate layer having a certain degree of orientation is formed, Excellent superconducting properties.

As the superconducting film, an RE-123-based oxide superconductor, that is, RE ₁ Ba ₂ Cu ₃ O _7-δ or the like is preferably used. As a formation method, a known method such as a PLD method, an MOD method, or an MOCVD method can be used.

  If necessary, a stabilizing layer such as a silver stabilizing layer or a copper stabilizing layer is formed on the superconducting film.

  According to the present invention, when a superconducting thin film wire is produced by continuously forming an intermediate layer on a long oriented metal substrate and further forming an oxide superconducting thin film, it is possible to suppress deterioration in superconducting characteristics. And a superconducting thin film wire can be obtained with a high yield.

It is sectional drawing which shows typically the structure of the orientation metal tape of the base material for superconducting thin film wires of one Example of this invention. It is a figure which shows typically the structure of the metal substrate of the base material for superconducting thin film wires of one Example of this invention. It is a figure which shows typically the structure of the base material for superconducting thin film wires of one Example of this invention. It is a figure which shows the (200) orientation rate of the intermediate | middle layer (seed film) formed on the metal substrate of the base material for superconducting thin film wires of one Example of this invention. It is sectional drawing which shows typically the structure of the superconducting thin film wire of one Example of this invention. It is a figure which shows typically the structure of the base material for superconducting thin film wires of a comparative example. It is a figure which shows the (200) orientation rate of the intermediate | middle layer (seed film) formed on the metal substrate of the base material for superconducting thin film wires of a comparative example.

  Hereinafter, the present invention will be described based on embodiments.

(Example)
In this example, a long metal substrate composed of a Ni / Cu / SUS oriented metal tape and a SUS non-oriented metal tape was used, and three layers of CeO ₂ / YSZ / CeO ₂ were formed on this metal substrate. This is an example in which a base material for a superconducting thin film wire is produced by forming an intermediate layer made of

[1] Production of substrate for superconducting thin film wire First, production of a substrate for superconducting thin film wire will be described in the order of steps.

1. Metal substrate production process (1) Oriented metal tape First, an oriented metal tape was produced. FIG. 1 is a cross-sectional view schematically showing a configuration of an oriented metal tape 11 of a substrate for a superconducting thin film wire according to the present embodiment. In this embodiment, a Ni layer 113 having a thickness of 1 μm is formed on a SUS plate 111 made of SUS316L having a thickness of 100 μm on a substrate having a Cu layer 112 having a thickness of 18 μm by plating. An oriented metal tape (thickness 119 μm × width 30 mm × length 30 m) 11 provided with a Ni / Cu biaxially oriented layer was prepared.

(2) Non-oriented metal tape Next, a metal tape made of SUS316L having the same width and thickness as the oriented metal tape 11 was cut into a length of 5 m to prepare a non-oriented metal tape.

(3) Production of Metal Substrate Next, as shown in FIG. 2, after placing and connecting the non-oriented metal tape 12 between two adjacent oriented metal tapes 11, a reducing gas (H ₂ gas 3 Molten metal, Ar gas 97 mol%) In an atmosphere, heat treatment was performed at a pressure of 8 Pa and 950 ° C. for 20 minutes to produce a long metal substrate 1. In FIG. 2, (a) is a plan view and (b) is a side view.

2. Intermediate Layer Forming Step FIGS. 3A and 3B are diagrams schematically showing a configuration of a base material 2 for a superconducting thin film wire having an intermediate layer formed on a metal substrate 1, wherein FIG. 3A is a side view, and FIG. It is sectional drawing in the location of the orientation metal tape 11 of. In FIG. 3, reference numeral 21 denotes an intermediate layer, and the intermediate layer 21 includes a CeO ₂ seed layer (seed film) 211, a YSZ barrier layer 212, and a CeO ₂ cap layer 213.

(1) Formation of CeO ₂ seed layer (seed film) First, using an RF sputtering method, a reducing gas (H ₂ gas 3 mol%, Ar gas 97 mol%) atmosphere, pressure 5.2 Pa, temperature 700 CeO ₂ was epitaxially grown on the metal substrate 1 at a temperature of 0.15 μm to form a CeO ₂ seed layer (seed film) 211 continuously over the entire length of the metal substrate 1.

(2) Measurement of (200) orientation rate a. Measurement Method Next, I (200) and I (111) of the CeO ₂ seed layer (seed film) 211 formed on the metal substrate 1 were sequentially measured from the tip of the metal substrate 1, and the following formula ( 200) The orientation ratio (%) was determined.
(200) Orientation rate (%)
= [I (200) / {I (200) + I (111)}] × 100

b. Measurement Result FIG. 4 shows the measurement result. In FIG. 4, the vertical axis represents the (200) orientation rate, and the horizontal axis represents the distance from the tip of the metal substrate 1. From FIG. 4, the (200) orientation ratio is almost 100% in the portion from the start of film formation to the rear end of the oriented metal tape 11 slightly before 30 m, that is, the portion excluding the rear end portion, and slightly in the rear end portion. It turns out that it has fallen. However, the (200) orientation rate is maintained at 90% or more in the rear end portion.

  Further, it becomes non-oriented once between 30-35 m, that is, on the non-oriented metal tape 12, but when it reaches a place beyond 35 m, that is, on the next oriented metal tape 11, the (200) orientation rate is 100%, It can be seen that the level has risen to the same level as immediately after the start of film formation. It can be seen that the same phenomenon is repeated thereafter.

(3) Formation of YSZ barrier layer and CeO ₂ cap layer Next, the YSZ barrier layer 212 having a thickness of 0.25 μm is formed on the CeO ₂ seed layer (seed film) 211 by using an RF sputtering method, and then the thickness is increased. A CeO ₂ cap layer 213 having a thickness of 0.05 μm was epitaxially grown to complete the formation of the intermediate layer 21.

3. Next, the non-oriented metal tape is removed by cutting at the boundary between the oriented metal tape 11 and the non-oriented metal tape 12, and the non-oriented metal tape 12 is removed together with the intermediate layer formed thereon, for a plurality of superconducting thin film wires. A substrate 2 was obtained.

[2] Fabrication of superconducting thin film wire and evaluation of superconducting characteristics Next, fabrication of a superconducting thin film wire and evaluation of superconducting characteristics will be described.
1. Production of Superconducting Thin Film Wire FIG. 5 is a cross-sectional view schematically showing the configuration of the superconducting thin film wire 3 of one embodiment of the present invention. In FIG. 5, 31 is a superconducting film and 32 is a stabilization layer.

(1) Superconducting film forming step First, a 1.5 μm thick superconducting film 31 made of Gd ₁ Ba ₂ Cu ₃ O _{7-δ is} formed on the intermediate layer 21 of the superconducting thin film wire base material 2 using the PLD method. Formed.

(2) Stabilizing layer forming step Next, a silver stabilizing layer 321 having a thickness of 5 μm is formed on the upper surface of the superconducting film 31 and the rear surface of the oriented metal tape 11 by DC sputtering, and further, the silver stabilizing layer 321 A 10 μm-thick copper stabilization layer 322 was formed on the outside by plating, and the stabilization layer 32 was formed on both sides.

  Thereafter, cutting was performed, and finally a superconducting thin film wire 3 having a width of 2 mm was obtained.

2. Evaluation of Superconducting Characteristics Superconducting characteristics Ic in a 77K self-magnetic field of all superconducting thin film wires produced using a substrate for superconducting thin film wires produced from one metal substrate were measured. As a result, the Ic of all the produced superconducting thin film wires was about 250 A / cm, and it was confirmed that the superconducting properties were good.

(Comparative example)
1. Preparation of substrate for superconducting thin film wire (1) Preparation of metal substrate and formation of intermediate layer An intermediate layer was formed on a metal substrate made of only an oriented metal tape over the entire length to prepare a substrate for a superconducting thin film wire. FIG. 6 is a diagram schematically showing the configuration of the base material 4 for the superconducting thin film wire of the comparative example. The metal tape 41 and the intermediate layer 42 of the base material 4 for the superconducting thin film wire of the comparative example shown in FIG. The configuration, width, and thickness are the same as those of the oriented metal tape 11 and the intermediate layer 21 of the substrate 2 for superconducting thin film wires shown in 3 (b).

(2) the formation of the measured intermediate layer 42 of (200) orientation ratio of CeO ₂ seed layer (seed film), in the same manner as in Example, CeO ₂ seed layer seed layer CeO ₂ seed layer (seed film) after the formation ) Was measured. The measurement results are shown in FIG. From FIG. 7, in the case of the comparative example, the (200) orientation rate is almost 100% in the portion from the start of the formation of the CeO ₂ seed layer (seed film) to slightly before 30 m, but gradually from slightly before 30 m. It can be seen that after 30 m, it suddenly decreases and finally decreases to about 20%.

2. Production of Superconducting Thin Film Wire After forming a superconducting film and a stabilizing layer on the substrate 4 for superconducting thin film wire shown in FIG. 6, a cutting process was performed, and the width was 2 mm as in the example. A superconducting thin film wire was obtained.

3. Evaluation of Superconducting Properties In the same manner as in the examples, the superconducting properties Ic of all the prepared superconducting thin film wires under a 77K self-magnetic field were measured. As a result, the superconducting thin film wire produced from the substrate for the superconducting thin film wire using the metal substrate up to 30 m from the start of the formation of the CeO ₂ seed layer (seed film) has excellent superconducting characteristics with an Ic of 250 A / cm. However, it was found that the remaining superconducting wire had a low Ic of 100 A / cm or less and poor superconducting properties.

  While the present invention has been described based on the embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

DESCRIPTION OF SYMBOLS 1 Metal substrate 2, 4 Base material for superconducting thin film wire 3 Superconducting thin film wire 11 Oriented metal tape 12 Unoriented metal tape 21, 42 Intermediate layer 31 Superconducting film 32 Stabilization layer 41 Metal tape 111 SUS plate 112 Cu layer 113 Ni layer 211 CeO ₂ seed layer (seed film)
212 YSZ barrier layer 213 CeO ₂ cap layer 321 Silver stabilization layer 322 Copper stabilization layer

Claims (6)

A method for producing a substrate for a superconducting thin film wire in which a biaxially oriented intermediate layer is formed on an orientation surface of a tape-like oriented metal substrate,
Metal substrate production for producing a long metal substrate by arranging and connecting a non-oriented metal tape of a predetermined length between two adjacent metal tapes of a plurality of aligned metal tapes of a predetermined length Process,
A method for producing a substrate for a superconducting thin film wire, comprising: an intermediate layer forming step of continuously forming the intermediate layer on a surface of the long metal substrate. After the intermediate layer forming step,
2. The production of a substrate for a superconducting thin film wire according to claim 1, further comprising a non-oriented metal tape removing step of cutting and removing the non-oriented metal tape together with an intermediate layer formed on the non-oriented metal tape. Method.   A substrate for a superconducting thin film wire, which is manufactured by the method for manufacturing a substrate for a superconducting thin film wire according to claim 1.   A substrate for a superconducting thin film wire, which is manufactured by the method for manufacturing a substrate for a superconducting thin film wire according to claim 2.   The substrate for a superconducting thin film wire according to claim 4, wherein the (200) orientation ratio of the intermediate layer is 90% or more.   A superconducting thin film wire comprising an oxide superconductor formed on an intermediate layer of the substrate for a superconducting thin film wire according to claim 4 or 5.

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