WO2013153651A1 - Oxide superconductor thin-film wiring material, and production method therefor - Google Patents
Oxide superconductor thin-film wiring material, and production method therefor Download PDFInfo
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- WO2013153651A1 WO2013153651A1 PCT/JP2012/060015 JP2012060015W WO2013153651A1 WO 2013153651 A1 WO2013153651 A1 WO 2013153651A1 JP 2012060015 W JP2012060015 W JP 2012060015W WO 2013153651 A1 WO2013153651 A1 WO 2013153651A1
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Definitions
- the present invention relates to an oxide superconducting thin film wire and a method for producing the same, and more particularly to an oxide superconducting thin film wire excellent in superconducting properties produced by a coating pyrolysis method and a method for producing the same.
- One method of manufacturing an oxide superconducting thin film wire is a coating pyrolysis method (Metal Organic Deposition, abbreviated as MOD method) (Japanese Patent Laid-Open No. 2007-165153 (Patent Document 1)).
- a metal organic compound solution is applied to a substrate to prepare a coating film (coating film manufacturing process), and then the metal organic compound is heat-treated (calcined) at, for example, around 500 ° C. to remove the organic component of the metal organic compound.
- Crystallization is achieved by thermally decomposing (calcination heat treatment step) and heat-treating (main firing) the obtained pyrolyzate (MOD calcined film) at a higher temperature (for example, around 800 ° C.) (main heat treatment step).
- a higher temperature for example, around 800 ° C.
- main heat treatment step To produce an oxide superconducting thin film made of an oxide superconductor represented by REBa 2 Cu 3 O 7-X (RE: rare earth element), for example, and is a gas phase method mainly produced in vacuum Compared with (evaporation method, sputtering method, pulsed laser deposition method, etc.), the manufacturing facility is simple, and it is easy to cope with a large area and a complicated shape.
- REBa 2 Cu 3 O 7-X rare earth element
- the inventor of the present invention paid attention to the formation of cavities and foreign substances (hereinafter referred to as voids together) together with the superconducting phase in the production of oxide superconducting thin film wires using the MOD method.
- the volume ratio (void ratio) occupied by the voids affects the superconducting characteristics, particularly the critical current density Jc. Has a certain negative correlation, and it was confirmed that even a slight change in porosity significantly affects Jc.
- the present inventor has examined the allowable porosity for obtaining a stable and excellent superconducting characteristic, and as a result, by setting the porosity to 10% or less, a stable and excellent superconductivity It was confirmed that a characteristic oxide superconducting thin film wire can be obtained.
- the invention according to claim 1 is based on the above knowledge, An oxide superconducting thin film wire in which an oxide superconducting thin film is formed on a substrate using a coating pyrolysis method, The oxide superconducting thin film has a porosity of 10% or less.
- the porosity of the oxide superconducting thin film wire is 10% or less, an oxide superconducting thin film wire having excellent and excellent superconducting properties, particularly excellent Jc, can be provided.
- the porosity is more preferably 5% or less, and further preferably 2% or less.
- the invention described in claim 2 2.
- the oxide superconducting thin film having excellent superconducting characteristics is formed over the entire length by controlling the porosity to 10% or less, the superconducting characteristics having excellent stability can be obtained. It is possible to provide an oxide superconducting thin film wire having high yield. As described above, the present invention exhibits a particularly remarkable effect in a long oxide superconducting thin film wire.
- metal substrate for example, a biaxially oriented Ni—W alloy substrate, an IBAD wire, a clad type oriented metal substrate in which SUS, Cu, and Ni (plating) are laminated are preferably used.
- the invention according to claim 3 The oxide superconducting thin film wire according to claim 1 or 2, wherein an intermediate layer is formed between the substrate and the oxide superconducting thin film.
- an intermediate layer between the superconducting thin film By providing the intermediate layer, an oxide superconducting thin film with good crystal orientation can be formed.
- the intermediate layer include a CeO 2 (cerium oxide) layer, a Y 2 O 3 (yttrium oxide) layer, and a YSZ (yttria stabilized zirconia) layer.
- the CeO 2 layer has a crystal orientation. It has a function as a seed crystal for forming a good oxide superconducting thin film and a function of performing lattice matching with the oxide superconducting thin film.
- the Y 2 O 3 layer has a function as a seed crystal.
- the YSZ layer has a function as a buffer layer that suppresses diffusion between the substrate and the oxide superconducting thin film.
- it can also be set as the intermediate
- the invention according to claim 4 The oxide superconducting thin film wire according to any one of claims 1 to 3, wherein a periphery of the oxide superconducting thin film wire is covered with a protective / stable layer.
- the oxide superconducting thin film wire is covered with a protective / stable layer of silver, copper, etc., so that the oxide superconducting thin film is protected from direct exposure to the atmosphere, etc., and is stable for a long period of time. Characteristics can be maintained.
- the invention described in claim 5 5.
- the thickness of the oxide superconducting thin film is too thin, the superconducting characteristics cannot be sufficiently exhibited even if the porosity is low.
- the invention described in claim 6 6.
- the oxide superconducting thin film If the oxide superconducting thin film is too thick, the oxide superconducting thin film cracks and inhibits the current, so that the superconducting characteristics cannot be fully exhibited.
- the invention described in claim 7 The oxide superconducting thin film according to any one of claims 1 and 6, wherein the oxide superconducting thin film is formed by a coating pyrolysis method using a metal organic compound containing no fluorine. It is a wire.
- the MOD method using a metal organic compound that does not contain fluorine differs from the TFA-MOD method using an organic acid salt containing fluorine. Because it does not generate dangerous gas such as hydrogen fluoride gas, it is environmentally friendly. Moreover, since it is not necessary to provide equipment for treating the generated hydrogen fluoride gas, an increase in cost can be suppressed, and an inexpensive oxide superconducting thin film wire can be provided.
- the invention according to claim 8 provides: It is a manufacturing method of the oxide superconducting thin film wire according to any one of claims 1 to 7, A coating film production process for producing a coating film by applying a solution of a metal organic compound on a substrate; A calcining heat treatment step for producing a calcined film by thermally decomposing and removing organic components contained in the metal organic compound of the coating film; A calcination heat treatment step of crystallizing the calcined film to produce an oxide superconducting thin film, The method for producing an oxide superconducting thin film wire, wherein a temperature increase rate in the calcining heat treatment step is 2 ° C./min or less.
- the rate of temperature rise is 2 ° C./min or less, the thermal decomposition of the organic component proceeds slowly and the decomposition gas tends to escape, so that generation of voids is suppressed and a dense calcined film can be formed. It is more preferably 1 ° C./min or less, and further preferably 0.5 ° C./min or less.
- the invention according to claim 9 is: 9.
- the intermediate heat treatment step of performing thermal decomposition of barium carbonate formed in the calcining heat treatment step is provided between the calcining heat treatment step and the main baking heat treatment step. It is a manufacturing method of an oxide superconducting thin film wire.
- the oxide superconducting thin film wire in this example includes a metal substrate 1 on which a SUS foil 11, a Cu thin film layer 12, and a Ni plating layer 13 are laminated, a Y 2 O 3 layer 21, a YSZ layer 22, The intermediate layer 2 on which the CeO 2 layer 23 is laminated and the YBCO oxide superconducting thin film layer 3 are configured.
- (2) Production of oxide superconducting thin film wire The YBCO oxide superconducting thin film wire was produced by the following steps. (A) Preparation of substrate An alignment metal substrate 1 was prepared as a substrate.
- a Y 2 O 3 layer 21 having a thickness of 100 nm, a YSZ single crystal layer 22 having a thickness of 400 nm, and a CeO 2 layer 23 having a thickness of 60 nm are formed in this order on the oriented metal substrate 1.
- An intermediate layer 2 composed of three layers was provided.
- FIG. 3 is a diagram showing a temperature profile of the heat treatment in this example. However, in FIG. 3, only the last three times are described in the calcination heat treatment process. The same applies to FIGS. 4 to 6.
- (I) Calcining heat treatment step The substrate on which the coating film has been formed is placed in an atmosphere furnace, and gradually heated up to 500 ° C.
- Comparative Example 1 The oxide of Comparative Example 1 was prepared in the same manner as in Example except that the temperature was raised to 500 ° C. at a rate of temperature increase of 10 ° C./min in the calcination heat treatment, and the calcined film was formed by holding for 30 minutes. A superconducting thin film wire was obtained. The temperature profile at this time is shown in FIG.
- the oxide superconducting thin film wire of the comparative example 2 was obtained like the comparative example 1 except not having performed intermediate heat processing.
- the temperature profile at this time is shown in FIG. 4).
- Evaluation The following evaluation was performed on the oxide superconducting thin film wires of Examples and Comparative Examples 1 and 2.
- (1) Porosity In FIG. 7, the SEM photograph of the cross section of the oxide superconducting thin film wire of an Example is shown. Note that the upper and lower photographs are the same photograph only by changing the contrast. As shown in FIG. 7, in the oxide superconducting thin film of the example, black portions indicating voids are hardly seen. Actually, the obtained porosity was 2%, which was an extremely small value.
Abstract
Provided is an oxide superconductor thin-film wiring material obtained by forming an oxide superconductor thin film on a substrate using metal organic deposition. The porosity of the oxide superconductor thin film is not more than 10%. The oxide superconductor thin film is formed by metal organic deposition using a metal organic compound which does not include fluorine. A production method for the oxide superconductor thin-film wiring material is provided with: an applied-film producing step in which a solution of the metal organic compound is applied to a substrate to produce an applied film; a preliminary calcination step in which organic components included in the metal organic compound of the applied film are thermally decomposed and removed to produce a preliminary-calcination film; and a principal calcination step in which the preliminary-calcination film is crystallized to produce the oxide superconductor thin film. The rate of the temperature increase in the preliminary calcination step is not more than 2˚C/min.
Description
本発明は、酸化物超電導薄膜線材とその製造方法に関し、詳しくは、塗布熱分解法を用いて作製された超電導特性に優れた酸化物超電導薄膜線材とその製造方法に関する。
The present invention relates to an oxide superconducting thin film wire and a method for producing the same, and more particularly to an oxide superconducting thin film wire excellent in superconducting properties produced by a coating pyrolysis method and a method for producing the same.
液体窒素の温度で超電導性を有する高温超電導体の発見以来、ケーブル、限流器、マグネットなどの電力機器への応用を目指した高温超電導線材の開発が活発に行われている。中でも、酸化物超電導体を薄膜化した酸化物超電導薄膜線材が注目されている。
Since the discovery of high-temperature superconductors with 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, an oxide superconducting thin film wire obtained by thinning an oxide superconductor has attracted attention.
酸化物超電導薄膜線材の製造方法の１つに、塗布熱分解法（Ｍｅｔａｌ Ｏｒｇａｎｉｃ Ｄｅｐｏｓｉｔｉｏｎ、略称：ＭＯＤ法）がある（特開２００７－１６５１５３号公報（特許文献１））。この方法は、金属有機化合物溶液を基板に塗布して塗布膜を作製した後（塗布膜作製工程）、金属有機化合物を例えば５００℃付近で熱処理（仮焼）して金属有機化合物の有機成分を熱分解させ（仮焼熱処理工程）、得られた熱分解物（ＭＯＤ仮焼膜）をさらに高温（例えば８００℃付近）で熱処理（本焼）すること（本焼熱処理工程）により、結晶化を行って、例えばＲＥＢａ２Ｃｕ３Ｏ７－Ｘ（ＲＥ：希土類元素）で表される酸化物超電導体からなる酸化物超電導薄膜を製造するものであり、主に真空中で製造される気相法（蒸着法、スパッタ法、パルスレーザ蒸着法等）に比較して製造設備が簡単で済み、また大面積や複雑な形状への対応が容易である等の特徴を有している。
One method of manufacturing an oxide superconducting thin film wire is a coating pyrolysis method (Metal Organic Deposition, abbreviated as MOD method) (Japanese Patent Laid-Open No. 2007-165153 (Patent Document 1)). In this method, a metal organic compound solution is applied to a substrate to prepare a coating film (coating film manufacturing process), and then the metal organic compound is heat-treated (calcined) at, for example, around 500 ° C. to remove the organic component of the metal organic compound. Crystallization is achieved by thermally decomposing (calcination heat treatment step) and heat-treating (main firing) the obtained pyrolyzate (MOD calcined film) at a higher temperature (for example, around 800 ° C.) (main heat treatment step). To produce an oxide superconducting thin film made of an oxide superconductor represented by REBa 2 Cu 3 O 7-X (RE: rare earth element), for example, and is a gas phase method mainly produced in vacuum Compared with (evaporation method, sputtering method, pulsed laser deposition method, etc.), the manufacturing facility is simple, and it is easy to cope with a large area and a complicated shape.
しかしながら、従来のＭＯＤ法による酸化物超電導薄膜線材の製造においては、充分に安定して優れた超電導特性の酸化物超電導薄膜線材が得られているとまでは言い難く、歩留まりが低下し、特に、ケーブルなどの長尺タイプにおいては問題となっていた。
However, in the production of the oxide superconducting thin film wire by the conventional MOD method, it is difficult to say that an oxide superconducting thin film wire having a sufficiently stable and excellent superconducting characteristic is obtained, and the yield is reduced. This has been a problem with long cable types.
そこで、ＭＯＤ法を用いて酸化物超電導薄膜線材を製造するに際して、安定して優れた超電導特性を有する酸化物超電導薄膜線材を得ることができる技術の開発が望まれていた。
Therefore, when manufacturing an oxide superconducting thin film wire using the MOD method, it has been desired to develop a technique capable of stably obtaining an oxide superconducting thin film wire having excellent superconducting characteristics.
本発明者は、ＭＯＤ法を用いた酸化物超電導薄膜線材の製造において、超電導相と共に空洞や異物（以下、両者を合わせて空隙と称する）が形成されていることに着目した。
The inventor of the present invention paid attention to the formation of cavities and foreign substances (hereinafter referred to as voids together) together with the superconducting phase in the production of oxide superconducting thin film wires using the MOD method.
そして、空隙の大きさ、個数、発生箇所等を種々解析する過程において、空隙の占める体積割合（空隙率）が超電導特性、特に臨界電流密度Ｊｃに影響を与えていること、空隙率とＪｃとは一定の負の相関関係にあること、そして、わずかな空隙率の変化でもＪｃに大きな影響を与えることを確認した。
In the process of analyzing the size, number, location, etc. of the voids, the volume ratio (void ratio) occupied by the voids affects the superconducting characteristics, particularly the critical current density Jc. Has a certain negative correlation, and it was confirmed that even a slight change in porosity significantly affects Jc.
そして、従来のＭＯＤ法による酸化物超電導薄膜線材の空隙率を調べたところ、２０％あり、この空隙率の大きさが、安定して優れた超電導特性の酸化物超電導薄膜線材を得ることを妨げていたことを確認した。
Then, when the porosity of the oxide superconducting thin film wire by the conventional MOD method was examined, it was found to be 20%, and the size of this porosity hindered obtaining an oxide superconducting thin film wire having excellent superconducting characteristics stably. I confirmed that it was.
以上の知見の下に、本発明者が、安定して優れた超電導特性を得るために許容される空隙率を検討した結果、空隙率を１０％以下にすることにより、安定して優れた超電導特性の酸化物超電導薄膜線材を得ることができることを確認した。
Based on the above knowledge, the present inventor has examined the allowable porosity for obtaining a stable and excellent superconducting characteristic, and as a result, by setting the porosity to 10% or less, a stable and excellent superconductivity It was confirmed that a characteristic oxide superconducting thin film wire can be obtained.
請求項１に記載の発明は、上記の知見に基づくものであって、
塗布熱分解法を用いて、基板上に酸化物超電導薄膜が形成されている酸化物超電導薄膜線材であって、
前記酸化物超電導薄膜の空隙率が１０％以下であることを特徴とする酸化物超電導薄膜線材である。 The invention according toclaim 1 is based on the above knowledge,
An oxide superconducting thin film wire in which an oxide superconducting thin film is formed on a substrate using a coating pyrolysis method,
The oxide superconducting thin film has a porosity of 10% or less.
塗布熱分解法を用いて、基板上に酸化物超電導薄膜が形成されている酸化物超電導薄膜線材であって、
前記酸化物超電導薄膜の空隙率が１０％以下であることを特徴とする酸化物超電導薄膜線材である。 The invention according to
An oxide superconducting thin film wire in which an oxide superconducting thin film is formed on a substrate using a coating pyrolysis method,
The oxide superconducting thin film has a porosity of 10% or less.
前記した通り、酸化物超電導薄膜線材の空隙率が１０％以下であれば、安定して優れた超電導特性、特に、優れたＪｃを有する酸化物超電導薄膜線材を提供することができる。５％以下の空隙率であればより好ましく、２％以下であればさらに好ましい。
As described above, when the porosity of the oxide superconducting thin film wire is 10% or less, an oxide superconducting thin film wire having excellent and excellent superconducting properties, particularly excellent Jc, can be provided. The porosity is more preferably 5% or less, and further preferably 2% or less.
請求項２に記載の発明は、
前記基板が金属基板であることを特徴とする請求項１に記載の酸化物超電導薄膜線材である。 The invention described inclaim 2
2. The oxide superconducting thin film wire according toclaim 1, wherein the substrate is a metal substrate.
前記基板が金属基板であることを特徴とする請求項１に記載の酸化物超電導薄膜線材である。 The invention described in
2. The oxide superconducting thin film wire according to
ＭＯＤ法における基板としては、ＹＳＺ（イットリア安定化ジルコニア）単結晶や金属基板が用いられる。ＹＳＺを基板とする酸化物超電導薄膜線材は、主に、タイル状で限流器等に使用されるが、長尺で用いる線材の場合、長尺化の容易性や曲げ加工のし易さなどの面から、金属基板上に酸化物超電導薄膜を形成することが好ましい。
As the substrate in the MOD method, a YSZ (yttria stabilized zirconia) single crystal or a metal substrate is used. Oxide superconducting thin film wires using YSZ as a substrate are mainly used for current limiters in the form of tiles, but in the case of long wires, easiness of elongating, easiness of bending, etc. From the above aspect, it is preferable to form an oxide superconducting thin film on a metal substrate.
このような、長尺化した酸化物超電導薄膜線材の場合、線材の１箇所でも超電導特性が悪い部分があると、線材全体に大きな影響を与える。
In the case of such a long oxide superconducting thin film wire, if there is a portion having poor superconducting characteristics even at one location of the wire, the entire wire is greatly affected.
本請求項の発明においては、空隙率を１０％以下に制御して、長尺全体に亘って優れた超電導特性を有する酸化物超電導薄膜が形成されているため、安定して優れた超電導特性を有する酸化物超電導薄膜線材を、歩留まりよく提供することができる。このように、本発明は、長尺の酸化物超電導薄膜線材において、特に顕著な効果を発揮する。
In the invention of this claim, since the oxide superconducting thin film having excellent superconducting characteristics is formed over the entire length by controlling the porosity to 10% or less, the superconducting characteristics having excellent stability can be obtained. It is possible to provide an oxide superconducting thin film wire having high yield. As described above, the present invention exhibits a particularly remarkable effect in a long oxide superconducting thin film wire.
なお、金属基板としては、例えば、２軸配向したＮｉ－Ｗ合金基板やＩＢＡＤ線材、ＳＵＳ、Ｃｕ、Ｎｉ（メッキ）が積層されたクラッド型の配向金属基板などが好ましく用いられる。
As the metal substrate, for example, a biaxially oriented Ni—W alloy substrate, an IBAD wire, a clad type oriented metal substrate in which SUS, Cu, and Ni (plating) are laminated are preferably used.
請求項３に記載の発明は、
前記基板と酸化物超電導薄膜との間に中間層が形成されていることを特徴とする請求項１または請求項２に記載の酸化物超電導薄膜線材である。 The invention according toclaim 3
The oxide superconducting thin film wire according to claim 1 or 2, wherein an intermediate layer is formed between the substrate and the oxide superconducting thin film.
前記基板と酸化物超電導薄膜との間に中間層が形成されていることを特徴とする請求項１または請求項２に記載の酸化物超電導薄膜線材である。 The invention according to
The oxide superconducting thin film wire according to claim 1 or 2, wherein an intermediate layer is formed between the substrate and the oxide superconducting thin film.
熱処理に際して、基板と酸化物超電導薄膜との間で、結晶格子の不整合が発生したり、相互に原子拡散が発生したりして、超電導特性の低下を招く恐れがあるため、基板と酸化物超電導薄膜との間に、中間層を設けることが好ましい。中間層を設けることにより、結晶配向の良好な酸化物超電導薄膜を形成させることができる。
During the heat treatment, there is a possibility that crystal lattice mismatching occurs between the substrate and the oxide superconducting thin film or atomic diffusion occurs between the substrates and the superconducting properties. It is preferable to provide an intermediate layer between the superconducting thin film. By providing the intermediate layer, an oxide superconducting thin film with good crystal orientation can be formed.
具体的な中間層としては、例えば、ＣｅＯ２（酸化セリウム）層、Ｙ２Ｏ３（酸化イットリウム）層、ＹＳＺ（イットリア安定化ジルコニア）層などを挙げることができ、ＣｅＯ２層は、結晶配向の良好な酸化物超電導薄膜を形成させる種結晶としての機能や、酸化物超電導薄膜との格子整合を行う機能を有する。そして、Ｙ２Ｏ３層は、種結晶としての機能を有する。また、ＹＳＺ層は、基板と酸化物超電導薄膜との間の拡散を抑制するバッファ層としての機能を有する。なお、これらを組み合わせて複数層からなる中間層とすることもできる。
Specific examples of the intermediate layer include a CeO 2 (cerium oxide) layer, a Y 2 O 3 (yttrium oxide) layer, and a YSZ (yttria stabilized zirconia) layer. The CeO 2 layer has a crystal orientation. It has a function as a seed crystal for forming a good oxide superconducting thin film and a function of performing lattice matching with the oxide superconducting thin film. The Y 2 O 3 layer has a function as a seed crystal. Further, the YSZ layer has a function as a buffer layer that suppresses diffusion between the substrate and the oxide superconducting thin film. In addition, it can also be set as the intermediate | middle layer which consists of multiple layers combining these.
請求項４に記載の発明は、
前記酸化物超電導薄膜線材の周囲が、保護・安定層により被覆されていることを特徴とする請求項１ないし請求項３のいずれか１項に記載の酸化物超電導薄膜線材である。 The invention according to claim 4
The oxide superconducting thin film wire according to any one ofclaims 1 to 3, wherein a periphery of the oxide superconducting thin film wire is covered with a protective / stable layer.
前記酸化物超電導薄膜線材の周囲が、保護・安定層により被覆されていることを特徴とする請求項１ないし請求項３のいずれか１項に記載の酸化物超電導薄膜線材である。 The invention according to claim 4
The oxide superconducting thin film wire according to any one of
酸化物超電導薄膜線材の周囲が、銀や銅などの保護・安定層により被覆されることにより、酸化物超電導薄膜が直接大気等に触れることから保護され、長期間に亘って、安定して超電導特性を維持することができる。
The oxide superconducting thin film wire is covered with a protective / stable layer of silver, copper, etc., so that the oxide superconducting thin film is protected from direct exposure to the atmosphere, etc., and is stable for a long period of time. Characteristics can be maintained.
請求項５に記載の発明は、
前記酸化物超電導薄膜の厚みが、０．１μｍ以上であることを特徴とする請求項１または請求項４のいずれか１項に記載の酸化物超電導薄膜線材である。 The invention described in claim 5
5. The oxide superconducting thin film wire according toclaim 1, wherein the oxide superconducting thin film has a thickness of 0.1 μm or more.
前記酸化物超電導薄膜の厚みが、０．１μｍ以上であることを特徴とする請求項１または請求項４のいずれか１項に記載の酸化物超電導薄膜線材である。 The invention described in claim 5
5. The oxide superconducting thin film wire according to
酸化物超電導薄膜の厚みが薄すぎると、空隙率が低くても、超電導特性を充分に発揮させることができない。
If the thickness of the oxide superconducting thin film is too thin, the superconducting characteristics cannot be sufficiently exhibited even if the porosity is low.
請求項６に記載の発明は、
前記酸化物超電導薄膜の厚みが、３μｍ以下であることを特徴とする請求項１または請求項５のいずれか１項に記載の酸化物超電導薄膜線材である。 The invention described in claim 6
6. The oxide superconducting thin film wire according toclaim 1, wherein the oxide superconducting thin film has a thickness of 3 μm or less.
前記酸化物超電導薄膜の厚みが、３μｍ以下であることを特徴とする請求項１または請求項５のいずれか１項に記載の酸化物超電導薄膜線材である。 The invention described in claim 6
6. The oxide superconducting thin film wire according to
酸化物超電導薄膜の厚みが厚すぎると、酸化物超電導薄膜にクラックが入り、電流を阻害するため、超電導特性を充分に発揮させることができない。
If the oxide superconducting thin film is too thick, the oxide superconducting thin film cracks and inhibits the current, so that the superconducting characteristics cannot be fully exhibited.
請求項７に記載の発明は、
前記酸化物超電導薄膜が、フッ素を含まない金属有機化合物を用いた塗布熱分解法により形成されていることを特徴とする請求項１または請求項６のいずれか１項に記載の酸化物超電導薄膜線材である。 The invention described in claim 7
The oxide superconducting thin film according to any one ofclaims 1 and 6, wherein the oxide superconducting thin film is formed by a coating pyrolysis method using a metal organic compound containing no fluorine. It is a wire.
前記酸化物超電導薄膜が、フッ素を含まない金属有機化合物を用いた塗布熱分解法により形成されていることを特徴とする請求項１または請求項６のいずれか１項に記載の酸化物超電導薄膜線材である。 The invention described in claim 7
The oxide superconducting thin film according to any one of
フッ素を含まない金属有機化合物を用いたＭＯＤ法（フッ素フリーＭＯＤ法）は、フッ素を含む有機酸塩を用いるＴＦＡ－ＭＯＤ法と異なり、仮焼熱処理工程や本焼熱処理工程などの熱処理工程において、フッ化水素ガスのような危険なガスを発生することがないため、環境にやさしい。また、発生したフッ化水素ガスを処理する設備を設ける必要がないため、コストの上昇を抑制することができ、安価な酸化物超電導薄膜線材を提供することができる。
Unlike the TFA-MOD method using a fluorine-containing organic acid salt, the MOD method using a metal organic compound that does not contain fluorine differs from the TFA-MOD method using an organic acid salt containing fluorine. Because it does not generate dangerous gas such as hydrogen fluoride gas, it is environmentally friendly. Moreover, since it is not necessary to provide equipment for treating the generated hydrogen fluoride gas, an increase in cost can be suppressed, and an inexpensive oxide superconducting thin film wire can be provided.
請求項８に記載の発明は、
請求項１ないし請求項７のいずれか１項に記載の酸化物超電導薄膜線材の製造方法であって、
基板上に金属有機化合物の溶液を塗布して塗布膜を作製する塗布膜作製工程と、
前記塗布膜の金属有機化合物に含有される有機成分を熱分解、除去して、仮焼膜を作製する仮焼熱処理工程と、
前記仮焼膜を結晶化させて、酸化物超電導薄膜を作製する本焼熱処理工程と
を備えており、
前記仮焼熱処理工程における昇温速度が、２℃／分以下であることを特徴とする酸化物超電導薄膜線材の製造方法である。 The invention according to claim 8 provides:
It is a manufacturing method of the oxide superconducting thin film wire according to any one ofclaims 1 to 7,
A coating film production process for producing a coating film by applying a solution of a metal organic compound on a substrate;
A calcining heat treatment step for producing a calcined film by thermally decomposing and removing organic components contained in the metal organic compound of the coating film;
A calcination heat treatment step of crystallizing the calcined film to produce an oxide superconducting thin film,
The method for producing an oxide superconducting thin film wire, wherein a temperature increase rate in the calcining heat treatment step is 2 ° C./min or less.
請求項１ないし請求項７のいずれか１項に記載の酸化物超電導薄膜線材の製造方法であって、
基板上に金属有機化合物の溶液を塗布して塗布膜を作製する塗布膜作製工程と、
前記塗布膜の金属有機化合物に含有される有機成分を熱分解、除去して、仮焼膜を作製する仮焼熱処理工程と、
前記仮焼膜を結晶化させて、酸化物超電導薄膜を作製する本焼熱処理工程と
を備えており、
前記仮焼熱処理工程における昇温速度が、２℃／分以下であることを特徴とする酸化物超電導薄膜線材の製造方法である。 The invention according to claim 8 provides:
It is a manufacturing method of the oxide superconducting thin film wire according to any one of
A coating film production process for producing a coating film by applying a solution of a metal organic compound on a substrate;
A calcining heat treatment step for producing a calcined film by thermally decomposing and removing organic components contained in the metal organic compound of the coating film;
A calcination heat treatment step of crystallizing the calcined film to produce an oxide superconducting thin film,
The method for producing an oxide superconducting thin film wire, wherein a temperature increase rate in the calcining heat treatment step is 2 ° C./min or less.
従来の酸化物超電導薄膜線材の空隙率が大きかった原因を検討したところ、従来のＭＯＤ法の場合、昇温速度を５～１０℃／分として、急激な昇温を行っているため、金属有機化合物の有機成分が急激に分解して一気に分解ガスが発生し、空隙が発生しやすく、空隙率が大きくなっていることが分かった。
The reason why the porosity of the conventional oxide superconducting thin film wire was large was examined. In the case of the conventional MOD method, the rate of temperature increase was 5 to 10 ° C./min. It was found that the organic component of the compound was rapidly decomposed to generate decomposition gas at a stretch, voids were easily generated, and the porosity was increased.
昇温速度を２℃／分以下とすれば、有機成分の熱分解が緩やかに進行して分解ガスが抜けやすいため、空隙の発生が抑制され、緻密な仮焼膜を形成させることができる。１℃／分以下であるとより好ましく、０．５℃／分以下であるとさらに好ましい。
When the rate of temperature rise is 2 ° C./min or less, the thermal decomposition of the organic component proceeds slowly and the decomposition gas tends to escape, so that generation of voids is suppressed and a dense calcined film can be formed. It is more preferably 1 ° C./min or less, and further preferably 0.5 ° C./min or less.
請求項９に記載の発明は、
前記仮焼熱処理工程と前記本焼熱処理工程との間に、前記仮焼熱処理工程において形成された炭酸バリウムの熱分解を行う中間熱処理工程を備えていることを特徴とする請求項８に記載の酸化物超電導薄膜線材の製造方法である。 The invention according to claim 9 is:
9. The intermediate heat treatment step of performing thermal decomposition of barium carbonate formed in the calcining heat treatment step is provided between the calcining heat treatment step and the main baking heat treatment step. It is a manufacturing method of an oxide superconducting thin film wire.
前記仮焼熱処理工程と前記本焼熱処理工程との間に、前記仮焼熱処理工程において形成された炭酸バリウムの熱分解を行う中間熱処理工程を備えていることを特徴とする請求項８に記載の酸化物超電導薄膜線材の製造方法である。 The invention according to claim 9 is:
9. The intermediate heat treatment step of performing thermal decomposition of barium carbonate formed in the calcining heat treatment step is provided between the calcining heat treatment step and the main baking heat treatment step. It is a manufacturing method of an oxide superconducting thin film wire.
仮焼熱処理工程において、バリウム有機化合物は熱分解されて炭酸バリウムを形成する。この炭酸バリウムをそのまま本焼熱処理すると、本焼温度は炭酸バリウムの熱分解温度よりも高いため、熱分解されて二酸化炭素を発生して、新たな空隙を発生させる恐れがある。
In the calcining heat treatment step, the barium organic compound is thermally decomposed to form barium carbonate. When this barium carbonate is subjected to a main heat treatment as it is, the main baking temperature is higher than the thermal decomposition temperature of barium carbonate, and therefore, there is a possibility that carbon dioxide is generated by heat decomposition and new voids are generated.
本請求項の発明においては、炭酸バリウムの熱分解を行う中間熱処理工程を設けているため、本焼熱処理において二酸化炭素の発生が抑制されて、より空隙の少ない緻密な仮焼膜を形成させることができる。
In the present invention, since an intermediate heat treatment step for thermal decomposition of barium carbonate is provided, generation of carbon dioxide is suppressed in the main heat treatment, and a dense calcined film with fewer voids can be formed. Can do.
本発明によれば、安定して所定の超電導特性を有するＭＯＤ法による酸化物超電導薄膜線材を歩留まりよく提供することができる。
According to the present invention, it is possible to provide an oxide superconducting thin film wire by the MOD method having a predetermined superconducting property stably and with a high yield.
以下、本発明を実施の形態に基づいて説明する。
１．空隙率と有効電流パスとの関係について
本発明者は、種々の実験を行い、空隙率と有効電流パスの関係を調べた。 Hereinafter, the present invention will be described based on embodiments.
1. Regarding Relationship Between Porosity and Effective Current Path The present inventor conducted various experiments and investigated the relationship between the porosity and the effective current path.
１．空隙率と有効電流パスとの関係について
本発明者は、種々の実験を行い、空隙率と有効電流パスの関係を調べた。 Hereinafter, the present invention will be described based on embodiments.
1. Regarding Relationship Between Porosity and Effective Current Path The present inventor conducted various experiments and investigated the relationship between the porosity and the effective current path.
具体的には、成膜条件を変えて、種々の空隙率の酸化物超電導薄膜を形成した多くの基板を準備し、一方から流した電流が他方でどの程度有効に取出せるかを調べた。
Specifically, many substrates on which oxide superconducting thin films with various porosity were formed by changing the film forming conditions were prepared, and it was examined how effectively the current flowed from one side can be taken out by the other side.
そして実験結果の解析にあたっては、パーコレーションモデルにより解析した。具体的にパーコレーションモデルを適用するにあたっては以下の式を用いた。
And in the analysis of the experimental result, it analyzed with the percolation model. In applying the percolation model specifically, the following formula was used.
但し、Ｋ：コネクティビティ（有効な電流パスの割合）
Ｐ：有効な電流経路の面積割合
Ｐｃ：パーコレーション閾値
（実験により決定される値で、二次元正方格子では、約０．５９）
図１は、このようにして求められた空隙率と有効電流パスとの関係を示す図であり、横軸が空隙率、縦軸が有効電流パスである。 Where K: Connectivity (Percentage of effective current paths)
P: Effective current path area ratio Pc: Percolation threshold (value determined by experiment, about 0.59 for a two-dimensional square lattice)
FIG. 1 is a diagram showing the relationship between the void ratio thus obtained and the effective current path, where the horizontal axis represents the void ratio and the vertical axis represents the effective current path.
Ｐ：有効な電流経路の面積割合
Ｐｃ：パーコレーション閾値
（実験により決定される値で、二次元正方格子では、約０．５９）
図１は、このようにして求められた空隙率と有効電流パスとの関係を示す図であり、横軸が空隙率、縦軸が有効電流パスである。 Where K: Connectivity (Percentage of effective current paths)
P: Effective current path area ratio Pc: Percolation threshold (value determined by experiment, about 0.59 for a two-dimensional square lattice)
FIG. 1 is a diagram showing the relationship between the void ratio thus obtained and the effective current path, where the horizontal axis represents the void ratio and the vertical axis represents the effective current path.
図１から、空隙率とＪｃとは負の相関関係にあること、そして、わずかな空隙率の変化でも、Ｊｃに大きな影響を与えることが分かる。そして、従来の空隙率が２０％の酸化物超電導薄膜の場合、有効電流パスが約４５％しかないことが分かる。
FIG. 1 shows that the porosity and Jc have a negative correlation, and that even a slight change in porosity has a large effect on Jc. In the case of the oxide superconducting thin film having a conventional porosity of 20%, it can be seen that the effective current path is only about 45%.
有効電流パスが７０％を下ると、充分なＪｃを安定して得ることが困難になる。このためには、図１より空隙率を１０％以下に抑える必要があることが分かる。
２．実施例
（１）酸化物超電導薄膜線材の構成
図２に、本実施例における酸化物超電導薄膜線材の断面図を模式的に示す。図２に示す通り、本実施例における酸化物超電導薄膜線材は、ＳＵＳ箔１１、Ｃｕ薄膜層１２、Ｎｉめっき層１３が積層された金属基板１と、Ｙ２Ｏ３層２１、ＹＳＺ層２２、ＣｅＯ２層２３が積層された中間層２と、ＹＢＣＯ酸化物超電導薄膜層３より構成されている。
（２）酸化物超電導薄膜線材の製造
以下の各工程により、上記のＹＢＣＯ酸化物超電導薄膜線材を製造した。
（ａ）基板の用意
基板として、配向金属基板１を用意した。
（ｂ）中間層作製工程
次に、前記配向金属基板１上に、厚み１００ｎｍのＹ２Ｏ３層２１、厚み４００ｎｍのＹＳＺ単結晶層２２、厚み６０ｎｍのＣｅＯ２層２３をこの順に形成させて、３層からなる中間層２を設けた。
（ｃ）ＭＯＤ溶液作製工程
Ｙ、Ｂａ、Ｃｕの各アセチルアセトナート塩から出発してＹ：Ｂａ：Ｃｕ＝１：２：３の比率（モル比）で合成し、アルコールを溶媒としたＭＯＤ溶液を作製した。なお、ＭＯＤ溶液のＹ３＋、Ｂａ２＋、Ｃｕ２＋を合わせた総カチオン濃度を１ｍｏｌ／Ｌとした。
（ｄ）塗布膜作製工程
次に、ダイコート法を用いて、前記ＭＯＤ溶液を中間層の上に塗布し、その後乾燥することにより、厚み１μｍの塗布膜を作製した。
（ｅ）熱処理工程
以下、本実施例における熱処理工程、具体的には、仮焼熱処理工程、中間熱処理工程、本焼熱処理工程につき、図３を用いて説明する。図３は、本実施例における熱処理の温度プロファイルを示す図である。但し、図３においては、仮焼熱処理工程は、最後の３回分だけを記載している。なお、図４～図６においても同様である。
（ｉ）仮焼熱処理工程
塗布膜が形成された基板を雰囲気炉内に配置し、大気中、５００℃まで２℃／分の昇温速度で徐々に昇温させ、３０分保持して厚み０．２μｍの仮焼膜を作製した。その後、１℃／分の降温速度で室温まで降温して、仮焼膜を雰囲気炉より取り出した。 If the effective current path falls below 70%, it becomes difficult to stably obtain a sufficient Jc. For this purpose, it can be seen from FIG. 1 that the porosity needs to be suppressed to 10% or less.
2. Example (1) Configuration of Oxide Superconducting Thin Film Wire FIG. 2 schematically shows a cross-sectional view of the oxide superconducting thin film wire in this example. As shown in FIG. 2, the oxide superconducting thin film wire in this example includes ametal substrate 1 on which a SUS foil 11, a Cu thin film layer 12, and a Ni plating layer 13 are laminated, a Y 2 O 3 layer 21, a YSZ layer 22, The intermediate layer 2 on which the CeO 2 layer 23 is laminated and the YBCO oxide superconducting thin film layer 3 are configured.
(2) Production of oxide superconducting thin film wire The YBCO oxide superconducting thin film wire was produced by the following steps.
(A) Preparation of substrate Analignment metal substrate 1 was prepared as a substrate.
(B) Intermediate Layer Preparation Step Next, a Y 2 O 3 layer 21 having a thickness of 100 nm, a YSZsingle crystal layer 22 having a thickness of 400 nm, and a CeO 2 layer 23 having a thickness of 60 nm are formed in this order on the oriented metal substrate 1. An intermediate layer 2 composed of three layers was provided.
(C) MOD solution preparation step Starting from each acetylacetonate salt of Y, Ba and Cu, the MOD solution was synthesized at a ratio (molar ratio) of Y: Ba: Cu = 1: 2: 3 and using alcohol as a solvent. Was made. The total cation concentration of Y 3+ , Ba 2+ and Cu 2+ in the MOD solution was 1 mol / L.
(D) Coating film production | generation process Next, the said MOD solution was apply | coated on the intermediate | middle layer using the die-coating method, and the coating film with a thickness of 1 micrometer was produced by drying after that.
(E) Heat treatment step Hereinafter, the heat treatment step in this embodiment, specifically, the calcination heat treatment step, the intermediate heat treatment step, and the main heat treatment step will be described with reference to FIG. FIG. 3 is a diagram showing a temperature profile of the heat treatment in this example. However, in FIG. 3, only the last three times are described in the calcination heat treatment process. The same applies to FIGS. 4 to 6.
(I) Calcining heat treatment step The substrate on which the coating film has been formed is placed in an atmosphere furnace, and gradually heated up to 500 ° C. at a rate of 2 ° C./min in the air, maintained for 30 minutes, and having a thickness of 0 A 2 μm calcined film was prepared. Thereafter, the temperature was lowered to room temperature at a rate of 1 ° C./min, and the calcined film was taken out from the atmosphere furnace.
２．実施例
（１）酸化物超電導薄膜線材の構成
図２に、本実施例における酸化物超電導薄膜線材の断面図を模式的に示す。図２に示す通り、本実施例における酸化物超電導薄膜線材は、ＳＵＳ箔１１、Ｃｕ薄膜層１２、Ｎｉめっき層１３が積層された金属基板１と、Ｙ２Ｏ３層２１、ＹＳＺ層２２、ＣｅＯ２層２３が積層された中間層２と、ＹＢＣＯ酸化物超電導薄膜層３より構成されている。
（２）酸化物超電導薄膜線材の製造
以下の各工程により、上記のＹＢＣＯ酸化物超電導薄膜線材を製造した。
（ａ）基板の用意
基板として、配向金属基板１を用意した。
（ｂ）中間層作製工程
次に、前記配向金属基板１上に、厚み１００ｎｍのＹ２Ｏ３層２１、厚み４００ｎｍのＹＳＺ単結晶層２２、厚み６０ｎｍのＣｅＯ２層２３をこの順に形成させて、３層からなる中間層２を設けた。
（ｃ）ＭＯＤ溶液作製工程
Ｙ、Ｂａ、Ｃｕの各アセチルアセトナート塩から出発してＹ：Ｂａ：Ｃｕ＝１：２：３の比率（モル比）で合成し、アルコールを溶媒としたＭＯＤ溶液を作製した。なお、ＭＯＤ溶液のＹ３＋、Ｂａ２＋、Ｃｕ２＋を合わせた総カチオン濃度を１ｍｏｌ／Ｌとした。
（ｄ）塗布膜作製工程
次に、ダイコート法を用いて、前記ＭＯＤ溶液を中間層の上に塗布し、その後乾燥することにより、厚み１μｍの塗布膜を作製した。
（ｅ）熱処理工程
以下、本実施例における熱処理工程、具体的には、仮焼熱処理工程、中間熱処理工程、本焼熱処理工程につき、図３を用いて説明する。図３は、本実施例における熱処理の温度プロファイルを示す図である。但し、図３においては、仮焼熱処理工程は、最後の３回分だけを記載している。なお、図４～図６においても同様である。
（ｉ）仮焼熱処理工程
塗布膜が形成された基板を雰囲気炉内に配置し、大気中、５００℃まで２℃／分の昇温速度で徐々に昇温させ、３０分保持して厚み０．２μｍの仮焼膜を作製した。その後、１℃／分の降温速度で室温まで降温して、仮焼膜を雰囲気炉より取り出した。 If the effective current path falls below 70%, it becomes difficult to stably obtain a sufficient Jc. For this purpose, it can be seen from FIG. 1 that the porosity needs to be suppressed to 10% or less.
2. Example (1) Configuration of Oxide Superconducting Thin Film Wire FIG. 2 schematically shows a cross-sectional view of the oxide superconducting thin film wire in this example. As shown in FIG. 2, the oxide superconducting thin film wire in this example includes a
(2) Production of oxide superconducting thin film wire The YBCO oxide superconducting thin film wire was produced by the following steps.
(A) Preparation of substrate An
(B) Intermediate Layer Preparation Step Next, a Y 2 O 3 layer 21 having a thickness of 100 nm, a YSZ
(C) MOD solution preparation step Starting from each acetylacetonate salt of Y, Ba and Cu, the MOD solution was synthesized at a ratio (molar ratio) of Y: Ba: Cu = 1: 2: 3 and using alcohol as a solvent. Was made. The total cation concentration of Y 3+ , Ba 2+ and Cu 2+ in the MOD solution was 1 mol / L.
(D) Coating film production | generation process Next, the said MOD solution was apply | coated on the intermediate | middle layer using the die-coating method, and the coating film with a thickness of 1 micrometer was produced by drying after that.
(E) Heat treatment step Hereinafter, the heat treatment step in this embodiment, specifically, the calcination heat treatment step, the intermediate heat treatment step, and the main heat treatment step will be described with reference to FIG. FIG. 3 is a diagram showing a temperature profile of the heat treatment in this example. However, in FIG. 3, only the last three times are described in the calcination heat treatment process. The same applies to FIGS. 4 to 6.
(I) Calcining heat treatment step The substrate on which the coating film has been formed is placed in an atmosphere furnace, and gradually heated up to 500 ° C. at a rate of 2 ° C./min in the air, maintained for 30 minutes, and having a thickness of 0 A 2 μm calcined film was prepared. Thereafter, the temperature was lowered to room temperature at a rate of 1 ° C./min, and the calcined film was taken out from the atmosphere furnace.
上記塗布膜作製工程および仮焼熱処理工程を繰り返して、最終的に、８層構造の仮焼膜（合計厚み１．６μｍ）を作製した。
（ｉｉ）中間熱処理工程
５００℃で３０分保持して８層目の仮焼膜を作製した後、降温せず、さらに、２０℃／分の昇温速度で６８０℃まで昇温させ、９０分保持して、中間熱処理を行った。
（ｉｉｉ）本焼熱処理工程
その後、３０℃／分の昇温速度で７７０℃まで昇温させ、９０分保持して、本焼膜を作製した。次に、２℃／分の降温速度で、５００℃まで降温した後、酸素１００％雰囲気下でさらに１℃／分の降温速度で室温まで炉冷し、実施例の酸化物超電導薄膜線材を得た。
（ｆ）別の熱処理工程
なお、上記の熱処理工程は、例えば、図４に示す温度プロファイルで行うこともできる。即ち、本温度プロファイルでは、前記温度プロファイルと異なり、仮焼熱処理工程において、６００℃まで２℃／分の昇温速度で徐々に昇温させることにより、仮焼膜を作製し、その後、１℃／分の降温速度で室温まで降温する。その後の中間熱処理工程および本焼熱処理工程は、前記温度プロファイルと同様である。
３．比較例
仮焼熱処理において、１０℃／分の昇温速度で５００℃まで昇温し、３０分保持して仮焼膜を形成した他は、実施例と同様にして、比較例１の酸化物超電導薄膜線材を得た。このときの温度プロファイルを図５に示す。 The coating film preparation process and the calcining heat treatment process were repeated to finally produce a calcined film (total thickness 1.6 μm) having an eight-layer structure.
(Ii) Intermediate heat treatment step After maintaining the temperature at 500 ° C. for 30 minutes to produce the eighth calcined film, the temperature is not lowered, and the temperature is further increased to 680 ° C. at a rate of temperature increase of 20 ° C./min. The intermediate heat treatment was performed.
(Iii) Main firing heat treatment step Thereafter, the temperature was increased to 770 ° C. at a temperature increase rate of 30 ° C./min, and maintained for 90 minutes to prepare a main firing film. Next, after the temperature was lowered to 500 ° C. at a temperature lowering rate of 2 ° C./min, the furnace was further cooled to room temperature at a temperature lowering rate of 1 ° C./min in anoxygen 100% atmosphere to obtain the oxide superconducting thin film wire of the example. It was.
(F) Another heat treatment process In addition, said heat treatment process can also be performed with the temperature profile shown in FIG. 4, for example. That is, in the present temperature profile, unlike the temperature profile, in the calcining heat treatment step, a calcined film is produced by gradually raising the temperature to 600 ° C. at a rate of 2 ° C./min. The temperature is lowered to room temperature at a rate of temperature reduction per minute. The subsequent intermediate heat treatment step and main heat treatment step are the same as in the temperature profile.
3. Comparative Example The oxide of Comparative Example 1 was prepared in the same manner as in Example except that the temperature was raised to 500 ° C. at a rate of temperature increase of 10 ° C./min in the calcination heat treatment, and the calcined film was formed by holding for 30 minutes. A superconducting thin film wire was obtained. The temperature profile at this time is shown in FIG.
（ｉｉ）中間熱処理工程
５００℃で３０分保持して８層目の仮焼膜を作製した後、降温せず、さらに、２０℃／分の昇温速度で６８０℃まで昇温させ、９０分保持して、中間熱処理を行った。
（ｉｉｉ）本焼熱処理工程
その後、３０℃／分の昇温速度で７７０℃まで昇温させ、９０分保持して、本焼膜を作製した。次に、２℃／分の降温速度で、５００℃まで降温した後、酸素１００％雰囲気下でさらに１℃／分の降温速度で室温まで炉冷し、実施例の酸化物超電導薄膜線材を得た。
（ｆ）別の熱処理工程
なお、上記の熱処理工程は、例えば、図４に示す温度プロファイルで行うこともできる。即ち、本温度プロファイルでは、前記温度プロファイルと異なり、仮焼熱処理工程において、６００℃まで２℃／分の昇温速度で徐々に昇温させることにより、仮焼膜を作製し、その後、１℃／分の降温速度で室温まで降温する。その後の中間熱処理工程および本焼熱処理工程は、前記温度プロファイルと同様である。
３．比較例
仮焼熱処理において、１０℃／分の昇温速度で５００℃まで昇温し、３０分保持して仮焼膜を形成した他は、実施例と同様にして、比較例１の酸化物超電導薄膜線材を得た。このときの温度プロファイルを図５に示す。 The coating film preparation process and the calcining heat treatment process were repeated to finally produce a calcined film (total thickness 1.6 μm) having an eight-layer structure.
(Ii) Intermediate heat treatment step After maintaining the temperature at 500 ° C. for 30 minutes to produce the eighth calcined film, the temperature is not lowered, and the temperature is further increased to 680 ° C. at a rate of temperature increase of 20 ° C./min. The intermediate heat treatment was performed.
(Iii) Main firing heat treatment step Thereafter, the temperature was increased to 770 ° C. at a temperature increase rate of 30 ° C./min, and maintained for 90 minutes to prepare a main firing film. Next, after the temperature was lowered to 500 ° C. at a temperature lowering rate of 2 ° C./min, the furnace was further cooled to room temperature at a temperature lowering rate of 1 ° C./min in an
(F) Another heat treatment process In addition, said heat treatment process can also be performed with the temperature profile shown in FIG. 4, for example. That is, in the present temperature profile, unlike the temperature profile, in the calcining heat treatment step, a calcined film is produced by gradually raising the temperature to 600 ° C. at a rate of 2 ° C./min. The temperature is lowered to room temperature at a rate of temperature reduction per minute. The subsequent intermediate heat treatment step and main heat treatment step are the same as in the temperature profile.
3. Comparative Example The oxide of Comparative Example 1 was prepared in the same manner as in Example except that the temperature was raised to 500 ° C. at a rate of temperature increase of 10 ° C./min in the calcination heat treatment, and the calcined film was formed by holding for 30 minutes. A superconducting thin film wire was obtained. The temperature profile at this time is shown in FIG.
そして、中間熱処理を行わなかった他は、比較例１と同様にして、比較例２の酸化物超電導薄膜線材を得た。このときの温度プロファイルを図６に示す。
４．評価
実施例および比較例１、２の酸化物超電導薄膜線材について、以下の評価を行った。
（１）空隙率
図７に、実施例の酸化物超電導薄膜線材の断面のＳＥＭ写真を示す。なお、上下の写真は、コントラストを変化させただけで、同一の写真である。図７に示すように、実施例の酸化物超電導薄膜には、空隙を示す黒い箇所がほとんど見られない。実際、得られた空隙率は２％と、極めて小さな値であった。 And the oxide superconducting thin film wire of the comparative example 2 was obtained like the comparative example 1 except not having performed intermediate heat processing. The temperature profile at this time is shown in FIG.
4). Evaluation The following evaluation was performed on the oxide superconducting thin film wires of Examples and Comparative Examples 1 and 2.
(1) Porosity In FIG. 7, the SEM photograph of the cross section of the oxide superconducting thin film wire of an Example is shown. Note that the upper and lower photographs are the same photograph only by changing the contrast. As shown in FIG. 7, in the oxide superconducting thin film of the example, black portions indicating voids are hardly seen. Actually, the obtained porosity was 2%, which was an extremely small value.
４．評価
実施例および比較例１、２の酸化物超電導薄膜線材について、以下の評価を行った。
（１）空隙率
図７に、実施例の酸化物超電導薄膜線材の断面のＳＥＭ写真を示す。なお、上下の写真は、コントラストを変化させただけで、同一の写真である。図７に示すように、実施例の酸化物超電導薄膜には、空隙を示す黒い箇所がほとんど見られない。実際、得られた空隙率は２％と、極めて小さな値であった。 And the oxide superconducting thin film wire of the comparative example 2 was obtained like the comparative example 1 except not having performed intermediate heat processing. The temperature profile at this time is shown in FIG.
4). Evaluation The following evaluation was performed on the oxide superconducting thin film wires of Examples and Comparative Examples 1 and 2.
(1) Porosity In FIG. 7, the SEM photograph of the cross section of the oxide superconducting thin film wire of an Example is shown. Note that the upper and lower photographs are the same photograph only by changing the contrast. As shown in FIG. 7, in the oxide superconducting thin film of the example, black portions indicating voids are hardly seen. Actually, the obtained porosity was 2%, which was an extremely small value.
これに対して、比較例１の酸化物超電導薄膜線材の場合には空隙率が１１％であり、実施例に比べ、大きな空隙率を示していた。そして、比較例２の酸化物超電導薄膜線材の場合には空隙率が２５％であり、比較例１に比べ、さらに大きな空隙率を示していた。
（２）超電導特性の評価試験
実施例および比較例１、２の酸化物超電導薄膜のＪｃを、７７Ｋ、自己磁場下において測定した。 On the other hand, in the case of the oxide superconducting thin film wire of Comparative Example 1, the porosity was 11%, indicating a larger porosity than in the Examples. In the case of the oxide superconducting thin film wire of Comparative Example 2, the porosity was 25%, which was larger than that of Comparative Example 1.
(2) Evaluation test of superconducting characteristics Jc of the oxide superconducting thin films of Examples and Comparative Examples 1 and 2 was measured at 77K under a self magnetic field.
（２）超電導特性の評価試験
実施例および比較例１、２の酸化物超電導薄膜のＪｃを、７７Ｋ、自己磁場下において測定した。 On the other hand, in the case of the oxide superconducting thin film wire of Comparative Example 1, the porosity was 11%, indicating a larger porosity than in the Examples. In the case of the oxide superconducting thin film wire of Comparative Example 2, the porosity was 25%, which was larger than that of Comparative Example 1.
(2) Evaluation test of superconducting characteristics Jc of the oxide superconducting thin films of Examples and Comparative Examples 1 and 2 was measured at 77K under a self magnetic field.
比較例１の酸化物超電導薄膜のＪｃは０．５ＭＡ／ｃｍ２、比較例２の酸化物超電導薄膜のＪｃは０．１ＭＡ／ｃｍ２であったのに対して、実施例のＪｃは１ＭＡ／ｃｍ２であり、比較例に比べ大幅に向上していることが確認された。
The Jc of the oxide superconducting thin film of Comparative Example 1 was 0.5 MA / cm 2 , and the Jc of the oxide superconducting thin film of Comparative Example 2 was 0.1 MA / cm 2 , whereas the Jc of the Example was 1 MA / cm 2. It was confirmed that it was cm 2 and was significantly improved as compared with the comparative example.
以上、本発明を実施の形態に基づき説明したが、本発明は上記の実施の形態に限定されるものではない。本発明と同一および均等の範囲内において、上記の実施の形態に対して種々の変更を加えることが可能である。
As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to said embodiment. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.
１ 金属基板、２ 中間層、３ ＹＢＣＯ酸化物超電導薄膜層、１１ ＳＵＳ箔、１２ Ｃｕ薄膜層、１３ Ｎｉめっき層、２１ Ｙ２Ｏ３層、２２ ＹＳＺ単結晶層、２３ ＣｅＯ２層。
1 metal substrate, 2 intermediate layer, 3 YBCO oxide superconducting thin film layer, 11 SUS foil, 12 Cu thin film layer, 13 Ni plating layer, 21 Y 2 O 3 layer, 22 YSZ single crystal layer, 23 CeO 2 layer.
Claims (9)
- 塗布熱分解法を用いて、基板上に酸化物超電導薄膜が形成されている酸化物超電導薄膜線材であって、
前記酸化物超電導薄膜の空隙率が１０％以下であることを特徴とする酸化物超電導薄膜線材。 An oxide superconducting thin film wire in which an oxide superconducting thin film is formed on a substrate using a coating pyrolysis method,
An oxide superconducting thin film wire, wherein the oxide superconducting thin film has a porosity of 10% or less. - 前記基板が金属基板であることを特徴とする請求項１に記載の酸化物超電導薄膜線材。 The oxide superconducting thin film wire according to claim 1, wherein the substrate is a metal substrate.
- 前記基板と酸化物超電導薄膜との間に中間層が形成されていることを特徴とする請求項１または請求項２に記載の酸化物超電導薄膜線材。 The oxide superconducting thin film wire according to claim 1 or 2, wherein an intermediate layer is formed between the substrate and the oxide superconducting thin film.
- 前記酸化物超電導薄膜線材の周囲が、保護・安定層により被覆されていることを特徴とする請求項１ないし請求項３のいずれか１項に記載の酸化物超電導薄膜線材。 The oxide superconducting thin film wire according to any one of claims 1 to 3, wherein a periphery of the oxide superconducting thin film wire is covered with a protective / stable layer.
- 前記酸化物超電導薄膜の厚みが、０．１μｍ以上であることを特徴とする請求項１または請求項４のいずれか１項に記載の酸化物超電導薄膜線材。 5. The oxide superconducting thin film wire according to claim 1, wherein the oxide superconducting thin film has a thickness of 0.1 μm or more.
- 前記酸化物超電導薄膜の厚みが、３μｍ以下であることを特徴とする請求項１または請求項５のいずれか１項に記載の酸化物超電導薄膜線材。 The oxide superconducting thin film wire according to any one of claims 1 and 5, wherein the oxide superconducting thin film has a thickness of 3 µm or less.
- 前記酸化物超電導薄膜が、フッ素を含まない金属有機化合物を用いた塗布熱分解法により形成されていることを特徴とする請求項１または請求項６のいずれか１項に記載の酸化物超電導薄膜線材。 The oxide superconducting thin film according to any one of claims 1 and 6, wherein the oxide superconducting thin film is formed by a coating pyrolysis method using a metal organic compound containing no fluorine. wire.
- 請求項１ないし請求項７のいずれか１項に記載の酸化物超電導薄膜線材の製造方法であって、
基板上に金属有機化合物の溶液を塗布して塗布膜を作製する塗布膜作製工程と、
前記塗布膜の金属有機化合物に含有される有機成分を熱分解、除去して、仮焼膜を作製する仮焼熱処理工程と、
前記仮焼膜を結晶化させて、酸化物超電導薄膜を作製する本焼熱処理工程と
を備えており、
前記仮焼熱処理工程における昇温速度が、２℃／分以下であることを特徴とする酸化物超電導薄膜線材の製造方法。 It is a manufacturing method of the oxide superconducting thin film wire according to any one of claims 1 to 7,
A coating film production process for producing a coating film by applying a solution of a metal organic compound on a substrate;
A calcining heat treatment step for producing a calcined film by thermally decomposing and removing organic components contained in the metal organic compound of the coating film;
A calcination heat treatment step of crystallizing the calcined film to produce an oxide superconducting thin film,
The method for producing an oxide superconducting thin film wire, characterized in that a temperature rising rate in the calcining heat treatment step is 2 ° C./min or less. - 前記仮焼熱処理工程と前記本焼熱処理工程との間に、前記仮焼熱処理工程において形成された炭酸バリウムの熱分解を行う中間熱処理工程を備えていることを特徴とする請求項８に記載の酸化物超電導薄膜線材の製造方法。 9. The intermediate heat treatment step of performing thermal decomposition of barium carbonate formed in the calcining heat treatment step is provided between the calcining heat treatment step and the main calcining heat treatment step. Manufacturing method of oxide superconducting thin film wire.
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