JP2011096510A - Rare earth oxide superconducting wire material and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the orientation of an IBAD layer by forming a bed layer by an MOD method. <P>SOLUTION: In a superconducting wire material 10 manufactured by forming a MOD-CZO layer 2, an IBS-GZO 3, an IBAD-MgO layer 4, a LMO layer 5, a PLD-CeO<SB>2</SB>layer 6 and a PLD-GdBCO superconductive layer 8 in this order on an electropolished substrate 1, the CeO<SB>2</SB>layer has the orientation of Δϕ=4.1 deg., which is almost the same as the case of using a mechanically polished substrate, and the GdBCO superconductive layer has an Ic value of Ic=249 A (Jc-5 MA/cm<SP>2</SP>), which is almost the same as the case of using a mechanically polished substrate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rare earth oxide superconducting wire useful for a superconducting magnet, a superconducting cable, a power device, and the like, and an improvement of a manufacturing method thereof.

A rare earth oxide superconducting wire is generally formed by forming at least one or more biaxially oriented oxide layers on a metal substrate, forming an oxide superconducting layer thereon, and further protecting the surface of the superconducting layer and making electrical contact. It has a structure in which a stabilization layer that plays a role as a protection circuit in the case of improvement and overcurrent is laminated.

  In this case, it is known that the critical current characteristic of the superconducting wire depends on the in-plane orientation of the superconducting layer and is greatly affected by the in-plane orientation and surface smoothness of the orientation metal substrate and the intermediate layer as a base. .

Rare earth oxide superconductors, for example, YBa ₂ Cu ₃ O _7-δ (hereinafter referred to as YBCO) superconductors are orthorhombic and the length of three sides of the x-axis, y-axis, and z-axis However, the angle between the three sides of the unit cell is slightly different from each other, so it is easy to form twins.Small misorientation generates twin grain boundaries and deteriorates current conduction characteristics. In order to exhibit the characteristics, it is required not only to align the CuO plane in the crystal but also to align the crystal orientation in the plane, so that it is difficult to make the wire as compared with the Bi-based oxide superconductor. Accompany.

  The manufacturing method for increasing the in-plane orientation of the crystal of the rare earth oxide superconductor and forming the wire while aligning the in-plane orientation is the same as the manufacturing method of the thin film. That is, by forming an intermediate layer with improved in-plane orientation and orientation on a tape-shaped metal substrate and using the crystal lattice of this intermediate layer as a template, the in-plane orientation and orientation of the superconducting layer crystals can be reduced. It is to improve.

  Rare earth oxide superconductors are currently studied in various manufacturing processes, and various biaxially oriented composite substrates in which an in-plane oriented intermediate layer is formed on a tape-like metal substrate are known. As described above, since the critical current characteristics of the superconducting layer formed on the intermediate layer are greatly affected by the surface smoothness of the lower intermediate layer, how to form the surface smooth intermediate layer becomes a problem.

Currently, in superconductors in which a rare earth oxide superconducting layer is disposed on a substrate via an intermediate layer, one of the methods for forming an intermediate layer that exhibits the highest critical current characteristics is the IBAD (Ion Beam Assisted Deposition) method. Things are known. This method was generated from a target while irradiating ions on a polycrystalline non-magnetic high-strength tape-like Ni-based substrate (Hastelloy, etc.) from a certain angle with respect to the normal of the Ni-based substrate An intermediate layer (CeO ₂ , Y ₂ ) that deposits particles by a PLD (Pulsed Laser Deposition) method and has a fine crystal grain size and high orientation, and suppresses a reaction with an element constituting a superconductor. O ₃ , YSZ: yttria-stabilized zirconia) or an intermediate layer having a two-layer structure (YSZ or Rx ₂ Zr ₂ O ₇ / CeO ₂ or Y ₂ O ₃ etc .: Rx is Y, Nd, Sm, Gd, Ei, Yb , Ho, Tm, Dy, Ce, La or Er.), And CeO ₂ is formed thereon by the PLD method. A YBCO layer or the like is formed on the IBAD substrate by the PLD method or the CVD method. Completed Producing a superconducting wire with (e.g., see Patent Documents 1 and 2.).

  In recent years, since a composite substrate in which an oriented MgO intermediate layer (hereinafter referred to as IBAD-MgO) by the IBAD method is provided on a metal substrate, a crystalline film can be obtained at a high speed and the cost is low. It is attracting attention as a composite substrate for oxide superconducting wires.

  The IBAD-MgO film can achieve high speed because good biaxial orientation can be obtained in a very thin region having a film thickness of 10 nm or less. On the other hand, the smoothness of the substrate used for film formation is 2 of the IBAD-MgO layer. It is known to affect the axial orientation, and for this reason, conventionally, the surface of a metal substrate has been polished by machining, for example, a metal substrate having a smooth surface of Ra ≦ 2 nm that has been mechanically polished. Is used.

  On the other hand, in order to improve the orientation of the IBAD-MgO film, an intermediate layer serving as a base layer (bed layer) of the IBAD-MgO film is formed on the metal substrate, and the IBAD-MgO layer is formed on the bed layer. It is being considered to form. This bed layer also has a function of preventing diffusion of constituent elements of the metal substrate.

As a bed layer of the MgO layer by the IBAD method described above, a method using an amorphous layer is known. This is based on a first thin film having a biaxial orientation of a rock salt structure on a metal substrate having a smooth amorphous surface. And a second film made of a superconducting layer is provided on the buffer layer as a template. Specifically, on a substrate having a smooth surface Si ₃ N ₄ or SiO ₂ amorphous layer Then, an in-plane oriented MgO (100) layer is formed by the IBAD method. It has been reported that the Jc value of the YBCO layer can be improved by forming an amorphous layer, an IBAD-MgO layer, and a YBCO layer thereon using a Hastelloy having a smooth surface as the metal substrate. The layer is formed, for example, by performing laser processing, ion damage, high-speed machining, vapor deposition, or ion implantation on the surface of a Ni alloy such as Hastelloy (for example, see Non-Patent Document 1).

Further, a method using an oxide layer having a rock salt structure as a bed layer of an MgO layer by the IBAD method is known, which includes a first buffer layer made of a polycrystalline oxide disposed on a substrate, and a first buffer layer. A biaxially oriented second buffer layer made of IBAD-MgO, IBAD-CeO ₂ , IBAD- (RE) ₂ O ₃ ((RE) is a rare earth element) directly disposed on one buffer layer, and A superconducting layer disposed on the second buffer layer is provided. Specifically, on a Ni-based alloy substrate such as Hastelloy, a protective layer made of CeO ₂ or YSZ by PLD method, sputtering method, PLD method or MgO by evaporation, MgO of the first intermediate layer and the IBAD method comprising an oxide of sodium chloride structure such as NiO, YSZ, sequentially stacking a second intermediate layer composed of CeO ₂ or the like, YBC on this By forming the layer or the like, in which to improve the biaxial orientation of the superconducting layer on the second intermediate layer was biaxially oriented (e.g., see Non-Patent Document 2).

On the other hand, a method of forming an Al ₂ O ₃ / Y ₂ O ₃ or Gd ₂ Zr ₂ O ₇ intermediate layer formed by vapor deposition such as sputtering as a bed layer of the MgO layer by the IBAD method is also known. It has been.

JP-A-4-329867 Japanese Patent Laid-Open No. 4-331895

US Patent 6,190,752 B1 US Patent 7,071,149 B2

  As described above, a metal substrate having a smooth surface polished by machining is used to form the IBAD layer. This mechanically polished metal substrate can provide a very flat surface, but is locally polished. In addition to problems caused by defects, there is a problem that the cost is very high, and a bed layer deposited by a vapor phase method such as a sputtering method requires an expensive film forming apparatus for forming an intermediate layer. Therefore, there was a problem of causing an increase in cost.

  From the above, it is necessary to form a bed layer of an IBAD layer having a rock salt structure such as MgO on a substrate at low cost, to improve the orientation of the bed layer, and to further improve the orientation of the IBAD layer, For this reason, further smoothing of the bed layer is required without using mechanical polishing or a vapor phase method.

  The present invention has been made to solve the above problems, and in order to further improve the orientation of the IBAD layer without using a high-cost method such as mechanical polishing or vapor phase method, the bed layer is formed by the MOD method. It is an object of the present invention to provide a rare earth-based oxide superconducting wire excellent in superconducting characteristics and a method for producing the same, by improving the smoothness of the surface.

  In order to achieve the above object, the rare earth oxide superconducting wire of the present invention is an oxide superconducting wire in which a rare earth oxide superconducting layer is disposed on a substrate via a plurality of oxide intermediate layers. , Comprising at least a first intermediate layer formed on the substrate by the MOD method and at least a second intermediate layer formed on the first intermediate layer by the IBAD method. The rare earth oxide superconductivity is formed on the second intermediate layer. Layers are arranged.

  The rare earth oxide superconducting wire is an oxide superconducting wire in which a rare earth oxide superconducting layer is arranged on a substrate via a plurality of oxide intermediate layers, and the intermediate layer is formed at least on the substrate by the MOD method. And a rare earth-based oxide superconducting layer on the second intermediate layer via the template layer. The second intermediate layer is formed on the first intermediate layer by the IBAD method via the template layer. Can also be manufactured.

In the above invention, as the first intermediate layer, [RE] -Zr-O-based oxide ([RE] is Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb And one or more elements selected from Lu. The same shall apply hereinafter.) For example, [RE] ₂ Zr ₂ O ₇ or YSZ is preferably formed over the substrate by the MOD method.

The first intermediate layer preferably has a film thickness of 20 nm or more and 300 nm or less and a surface roughness Ra of 3 nm or less. The second intermediate layer made of the IBAD layer has a surface roughness Ra of 3 nm or less. It is preferably formed directly on the intermediate layer.
When the film thickness of the first intermediate layer is less than 20 nm, it becomes insufficient to prevent the diffusion of the constituent elements of the metal substrate. On the other hand, as the film thickness increases (the number of coatings increases), the smoothness improves. Since this smoothness tends to be saturated at a predetermined thickness or more, the film thickness is set to 300 nm or less.

  The second intermediate layer made of the IBAD layer is formed of MgO, Gd—Zr—O (GZO), YSZ or the like. In particular, IBAD-MgO can obtain a crystalline film at a high speed as described above. Moreover, it is preferable from the point of low cost.

The rare earth-based oxide superconducting wire layer in the present invention is REBa _x Cu ₃ O _y (RE is 1 or 2 selected from Y, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb. The superconducting layer is composed of MOD (Metal Organic Deposition: metal organic acid salt), which represents an element of more than species, and is composed of x ≦ 2 and y = 6.2 to 7, hereinafter referred to as REBCO. A film can be formed by a deposition) method, a PLD method, or a MOCVD method (Metal Organic Chemical Vapor Deposition), and the TFA-MOD method is particularly preferable as the film forming method.

  In the present invention, since the surface smoothness can be improved by forming the bed layer of the IBAD layer by the MOD method, a metal substrate with low smoothness can be used, and the polishing cost is reduced. In addition, the use of the MOD method, which is a non-vacuum process, makes it possible to significantly reduce the manufacturing cost, and the orientation of the IBAD layer can be made comparable to a mechanically polished metal substrate, and the superconducting rare earth oxide superconductivity. A wire can be easily manufactured.

It is a graph which shows the surface roughness with respect to the frequency | count of application | coating of the MOD-CZO layer used for one Example of the 1st intermediate | middle layer which concerns on this invention. It is a graph which shows the relationship between the calcination temperature of a MOD-CZO layer, a weight change, and a temperature difference. It is sectional drawing perpendicular | vertical to the axial direction of the rare earth type oxide superconducting wire in one Example of this invention. It is sectional drawing perpendicular | vertical to the axial direction of the rare earth type oxide superconducting wire in the other Example of this invention.

  In the present invention, the first intermediate layer such as [RE] -Zr-O-based oxide is formed by a MOD method. This MOD method uses a raw material solution in which an organic compound of a metal component is uniformly dissolved on a substrate. It is known as a method of forming a thin film on a substrate by heating and thermally decomposing it, and since it is a non-vacuum process, it can be formed at low cost and at high speed, so It has an advantage suitable for manufacturing a tape-shaped oxide superconducting wire.

  The REBCO layer in the present invention is preferably formed by the TFA-MOD method as described above, and this TFA-MOD method passes through a carbonate of an alkaline earth metal (Ba or the like) in the MOD method. Known as a method capable of obtaining a superconducting film having excellent in-plane orientation without requiring high-temperature heat treatment by solid-phase reaction, an organic acid salt containing fluorine (for example, TFA salt: trifluoroacetate) A superconductor is formed through the decomposition of fluoride by performing heat treatment in a steam atmosphere as a starting material. In the TFA-MOD method, a liquid phase resulting from HF is formed at the interface where the superconducting film grows while generating HF gas by the reaction between the amorphous precursor containing fluorine obtained after calcining of the coating film and water vapor. Since the superconductor is epitaxially grown from the substrate interface, it is necessary to quickly discharge the HF gas from the film surface. If the discharge is insufficient, the crystal growth rate of the superconductor is suppressed.

Conventionally, in the REBCO superconductor, there is a problem that it takes a lot of time to generate BaCeO ₃ by discharging a large amount of HF gas in the calcining process and reaction between the REBCO layer and the intermediate layer and to discharge the F element out of the film. In order to avoid this, the fluorine compound is reduced, and in the present invention, the molar ratio of Ba is set to a range of Ba <2, preferably 1.3 ≦ Ba ≦ 1.8. preferable.

By making the molar ratio of Ba smaller than the standard molar ratio (2), the segregation of Ba is suppressed, and the precipitation of Ba-based impurities at the grain boundaries is suppressed, so that the generation of cracks is suppressed. In addition, electrical connectivity between crystal grains is improved. Further, by reducing the Ba molar ratio, there is an advantage that Y ₂ Cu ₂ O ₅ and CuO which are magnetic flux pinning points are formed.

  Examples of the raw material solution of the REBCO superconductor by the above TFA-MOD method include (a) a metal organic acid salt solution containing RE, trifluoroacetate, naphthenate, octylate, levulinate containing RE. A solution containing any one or more of neodecanoate, in particular, a trifluoroacetate solution containing RE, (b) a metal organic acid salt solution containing Ba, and a solution of trifluoroacetate salt containing Ba and (c ) As the metal organic acid salt solution containing Cu, a solution containing one or more of naphthenate, octylate, levulinate and neodecanoate containing Cu is used.

  In the raw material solution, it is preferable to mix a metal organic acid salt solution containing one or more elements selected from Zr, Ce, Sn, or Ti into the raw material solution, so that the Zr is contained in the REBCO superconducting layer. It is possible to disperse oxides such as those as pinning points, and in particular, it is possible to improve the magnetic field characteristics of a YBCO superconductor having a large decrease rate of Ic value under a low magnetic field.

  That is, the TFA-MOD method has a problem that, unlike vapor phase growth, crystal growth is caused by a phase transformation from a precursor, so that the introduced magnetic flux pinning point is likely to be coarse and the introduction of the fine artificial pinning point is difficult. -Metal organic acid salt containing at least one metal selected from Zr, Ce, Sn or Ti having high affinity with Ba as a metal organic acid salt solution containing RE, Ba and Cu as a raw material solution by the MOD method By using a mixed solution made of a solution, oxide particles of 50 nm or less can be dispersed as a magnetic flux pinning point (see, for example, JP 2009-164010 A).

  The REBCO superconducting layer is laminated so as to have a predetermined film thickness after crystallization heat treatment by applying a raw material solution containing a metal element constituting the superconductor on the intermediate layer and repeating the calcination heat treatment a plurality of times. Formed.

  In the above invention, it is preferable to use a Ni-based alloy for the substrate. For example, Ni containing one or more elements selected from W, Mo, Cr, Fe, Cu, V, Sn, and Zn is used. it can.

  Examples of the present invention will be described below.

Example 1
(Number of MOD layer applications and surface roughness)
As a material for the bed layer of the IBAD layer, a CZO (Ce—Zr—O) layer, which has been proven as a barrier layer for a Ni—W alloy substrate, was formed on a Hastelloy substrate by the MOD method, and the smoothness thereof was investigated.

  As a metal substrate, a rolled up substrate (A) having a width of 5 mm and a thickness of 70 μm and an electropolished substrate (B) obtained by electropolishing the Hastelloy substrate are used. A naphthenic acid solution of Ce and Zr is DIPed on these substrates. Apply by coating method, continuously fired at 500 ° C in Ar atmosphere by RTR (Reel-to-Reel) type continuous firing furnace to form CZO layers with various thickness on Hastelloy substrate The surface roughness (Ra: nm) with respect to the number of times (times) was measured by observation with an atomic force microscope (AMF).

The initial surface roughness before application of the rolled up substrate (A) and the electropolished substrate (B) was Ra = 12.3 nm and 6.5 nm, respectively.
FIG. 1 shows the results of measuring the surface roughness (Ra: nm) with respect to the number of coatings (times) of the MOD-CZO layer. In the figure, ■ and ● are measured values of the rolled up substrate (A) and the electropolished substrate (B), respectively.

  From this result, for both the rolled up substrate (A) and the electropolished substrate (B), the Ra value tends to gradually decrease according to the number of times of application of the CZO layer, and in particular, the electropolished substrate (B). In some cases, the number of coatings is about 6 to 7 times, and the Ra value is reduced to about 3 nm, which shows smoothness equivalent to that of a mechanically polished substrate (up to 2 nm) that has been known to exhibit excellent superconducting properties. Yes.

  In addition, the effect of the MOD-CZO layer firing temperature was measured using a differential thermothermal gravimetric simultaneous measurement device, and the change in weight (TG) and temperature difference (starting of thermocouple) The relationship of power difference: μV) was measured.

The measurement results are shown in FIG. In the Ar atmosphere, the MOD-CZO film is thermally decomposed at about 400 ° C. and crystallized at about 500 ° C.
(Smoothness of CeO ₂ layer)
As shown in FIG. 3, the orientation of the intermediate layer is determined by MOD-CZO layer 2 formed on an electropolishing substrate 1 with Ra = 6.5 nm and a film thickness of about 80 nm and ion beam sputtering (IBS). A GZO (Gd ₂ Zr ₂ O ₇ ) layer 3 having a thickness of about 110 nm is formed as a template layer (of the IBAD-MgO layer), and an IBAD-MgO layer 4 having a thickness of 5 to 10 nm is formed thereon by sputtering ( After a LaMnO ₃ (LMO) layer 5 having a thickness of about 10 nm as a template layer (CeO ₂ layer) and a CeO ₂ layer 6 having a thickness of about 0.5 μm as a cap layer by the PLD method are sequentially formed, the CeO ₂ layer The orientation was evaluated.

As a result of measuring the in-plane orientation of the CeO ₂ layer 6 of the composite substrate 7 by the half width (FWHM) by X-ray diffraction (XRD), Δφ = 4.1 deg. showed that. This value is Δφ = ˜4 deg. When a mechanically polished substrate is used. It is about the same.
(Characteristics of REBCO layer)
On the CeO ₂ layer of the composite substrate 7 formed as described above, the GdBCO superconducting layer 8 having a film thickness of about 0.5 μm is formed by the PLD method, the Jc value is 77K, and the direct current four-terminal method in a self magnetic field. Was evaluated based on a voltage reference of 1 μV / cm.

The rare earth oxide superconducting wire 10 thus manufactured has a structure of [PLD-CeO ₂ / LMO / IBAD-MgO / IBS-GZO / MOD-CZO / electrolytic polishing substrate] as shown in FIG. And the GdBCO superconducting layer 8 showed the value of Ic = 249A (Jc-5MA / cm < ² >). This value was about the same as Jc = 5-6 MA / cm ² when a mechanical polishing substrate was used.

Example 2
Using a Ra = 5 nm electropolished substrate obtained by electropolishing a Hastelloy substrate, a MOD-CZO layer was formed on this substrate in the same manner as in Example 1, and an IBAD-MgO layer and an LMO layer (template layer) were formed thereon. Then, a CeO ₂ layer was formed to a thickness of 0.5 μm on this LMO layer to manufacture a composite substrate.

Further, a GdBCO superconducting layer having a film thickness of about 0.5 μm was formed on the CeO ₂ layer on the composite substrate by the PLD method.

The in-plane orientation and Ic of the CeO ₂ layer of the rare earth-based oxide superconducting wire 20 having this [PLD-GdBCO / PLD-CeO ₂ / LMO / IBAD-MgO / MOD-CZO / electrolytic polishing substrate] structure are shown in Example 1. As a result of measurement by the same method, Δφ = 6.4 deg. , Ic = 180A.

Example 3
As shown in FIG. 4, a Ra = 5 nm electropolished substrate 31 obtained by electropolishing a Hastelloy substrate was used, and a MOD-CZO layer 32 was formed on this substrate in the same manner as in Example 1, and IBAD- After the MgO layer 33 and the LMO layer 34 (template layer) were formed, a CeO ₂ layer 35 was formed on the LMO layer to a thickness of 1 μm to manufacture a composite substrate 36.

Further, a YBCO superconducting layer 37 having a film thickness of about 1.3 μm was formed on the CeO ₂ layer 35 on the composite substrate 36 by TFA-MOD method.

Example 1 shows the in-plane orientation and Ic of the CeO ₂ layer 35 of the rare earth oxide superconducting wire 30 having the [MOD-YBCO / PLD-CeO ₂ / LMO / IBAD-MgO / MOD-CZO / electrolytic polishing substrate] structure. As a result of measurement by the same method as above, Δφ = 4.6 deg. , Ic = 250A.

Example 4
An Ra = 5 nm electropolished substrate obtained by electropolishing a Hastelloy substrate was used, and a MOD-CZO layer, an IBS-GZO layer (template layer), an IBAD-MgO layer, an LMO layer (template) were formed on this substrate in the same manner as in Example 1. Layer) was sequentially formed, and then a CeO ₂ layer was formed to a thickness of 0.5 μm on this LMO layer to manufacture a composite substrate.

Further, on the CeO ₂ layer on the composite substrate, a GdBCO superconducting layer having a thickness of about 0.5 μm was formed by a PLD method and a YBCO superconducting layer having a thickness of about 1.4 μm by a TFA-MOD method, respectively.

This [PLD-GdBCO / PLD-CeO ₂ / LMO / IBAD-MgO / IBS-GZO / MOD-CZO / electrolytic polishing substrate] structure [1] and [MOD-YBCO / PLD-CeO ₂ / LMO / IBAD-MgO / IBS-GZO / MOD-CZO / electropolishing substrate] The in-plane orientation of the CeO ₂ layer of the rare earth oxide superconducting wire having the structure [2] was measured by the same method as in Example 1. As a result, Δφ = 4.9 deg. . The Ic values were Ic = 250A for the structure [1] and Ic = 303A for the structure [2], respectively.

Example 5
An electropolishing substrate with Ra = 5 nm obtained by electropolishing a Hastelloy substrate was used, and a MOD-CZO layer, an IBS-GZO layer (template layer), an IBAD-MgO layer, an LMO layer (template) were formed on this substrate in the same manner as in Example 4. Layer) was sequentially formed, and then a CeO ₂ layer was formed to a thickness of 1 μm on this LMO layer to produce a composite substrate.

Further, a YBCO superconducting layer having a thickness of about 1.4 μm was formed on the CeO ₂ layer on the composite substrate by the TFA-MOD method.

The in-plane orientation and Ic value of the CeO ₂ layer of the rare earth oxide superconducting wire having this [MOD-YBCO / PLD-CeO ₂ / LMO / IBAD-MgO / IBS-GZO / MOD-CZO / electrolytic polishing substrate] structure As a result of measurement by the same method as in Example 1, Δφ = 4.2 deg. A value of Ic = 330A was shown.

From the results of Examples 2 to 5 above, in the rare earth oxide superconducting wire in which the MOD-CZO layer is formed as the bed layer of the IBAD-MgO layer, the IBS-GZO layer is formed as the template layer of the IBAD-MgO layer. In this case, the orientation of the CeO ₂ layer and the Ic value of the PLD-GdBCO layer are slightly lower than those of the mechanically polished substrate at the film thickness of 0.5 μm, but the orientation of the CeO ₂ layer at the film thickness of 1 μm. It was confirmed that the Ic value of the TFA-YBCO layer showed the same value as that of the mechanically polished substrate.

On the other hand, in the rare-earth oxide superconducting wire in which the MOD-CZO layer is formed as the bed layer of the IBAD-MgO layer, when the IBS-GZO layer is formed as the template layer of the IBAD-MgO layer, the CeO ₂ layer While the orientation is 0.5 μm and shows the same value as that of the mechanically polished substrate, the Ic value of the PLD-GdBCO layer shows the same value as that of the mechanically polished substrate, and the Ic value of the TFA-YBCO layer is The value is equal to or greater than that of the mechanically polished substrate.

Furthermore, when the film thickness of the CeO ₂ layer is 1 μm, the orientation is equal to that of the mechanically polished substrate, and the Ic value of the TFA-YBCO layer is equal to or greater than that of the mechanically polished substrate. Yes.

  According to the present invention, the surface smoothness of the IBAD layer can be further improved, so that a low-cost metal substrate can be used, and a rare-earth oxide superconducting wire having excellent superconducting characteristics can be easily produced at a low cost. It is effective for the application of superconducting wires to superconducting magnets, superconducting cables and power equipment.

DESCRIPTION OF SYMBOLS 1, 31 Electropolishing substrate 2, 32 MOD-CZO layer 3 GZO layer 4, 33 IBAD-MgO layer 5, 34 LaMnO ₃ (LMO) layer 6, 35 CeO ₂ layer 7, 36 Composite substrate 8, GdBCO superconducting layer 10, 30 Rare earth oxide superconducting wire 37 YBCO superconducting layer

Claims (9)

  In an oxide superconducting wire in which a rare earth-based oxide superconducting layer is disposed on a substrate via a plurality of oxide intermediate layers, the intermediate layer includes at least a first intermediate layer formed on the substrate by a MOD method and at least A rare earth-based oxide superconducting wire comprising a second intermediate layer formed on the first intermediate layer by an IBAD method, wherein a rare earth-based oxide superconducting layer is disposed on the second intermediate layer.   The first intermediate layer is [RE] -Zr-O-based oxide ([RE] is selected from Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb, and Lu. 1 or 2 or more elements. The same shall apply hereinafter) or YSZ.   The rare earth-based oxide superconducting wire according to claim 1 or 2, wherein the first intermediate layer has a thickness of 20 nm or more and 300 nm or less.   The rare earth-based oxide superconducting wire according to any one of claims 1 to 3, wherein the surface roughness Ra of the first intermediate layer is 3 nm or less.   The rare earth-based oxide superconducting wire according to any one of claims 1 to 4, wherein the second intermediate layer is made of MgO. The rare earth-based oxide superconducting layer is made of REBa _x Cu ₃ O _y (RE is one or more elements selected from Y, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb. Wherein x ≦ 2 and y = 6.2 to 7. The same shall apply hereinafter.) The rare earth-based oxide superconducting wire according to any one of claims 1 to 5.   The rare earth-based oxide superconducting wire according to any one of claims 1 to 6, wherein the rare earth-based oxide superconducting layer is formed of a film formed by PLD, MOD, or MOCVD.   8. The template layer according to claim 1, further comprising a template layer between the first intermediate layer and the second intermediate layer and / or between the second intermediate layer and the rare earth-based oxide superconducting layer. Rare earth oxide superconducting wire. After forming a first intermediate layer made of [RE] -Zr-O-based oxide or YSZ having a surface roughness Ra of 20 nm or more and 300 nm or less and 3 nm or less on the substrate by the MOD method, A second intermediate layer made of MgO is formed on one intermediate layer by IBAD, and then a REBa _x Cu ₃ O _y superconducting layer is formed on the second intermediate layer by TFA-MOD. A method for producing a rare earth oxide superconducting wire.