JP5693398B2 - Oxide superconducting conductor and manufacturing method thereof - Google Patents
Oxide superconducting conductor and manufacturing method thereof Download PDFInfo
- Publication number
- JP5693398B2 JP5693398B2 JP2011142870A JP2011142870A JP5693398B2 JP 5693398 B2 JP5693398 B2 JP 5693398B2 JP 2011142870 A JP2011142870 A JP 2011142870A JP 2011142870 A JP2011142870 A JP 2011142870A JP 5693398 B2 JP5693398 B2 JP 5693398B2
- Authority
- JP
- Japan
- Prior art keywords
- layer
- oxide superconducting
- protective layer
- film
- crystal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000004020 conductor Substances 0.000 title claims description 43
- 238000004519 manufacturing process Methods 0.000 title claims description 11
- 239000010410 layer Substances 0.000 claims description 181
- 239000011241 protective layer Substances 0.000 claims description 90
- 239000013078 crystal Substances 0.000 claims description 48
- 239000000758 substrate Substances 0.000 claims description 31
- 239000000463 material Substances 0.000 claims description 29
- 238000010438 heat treatment Methods 0.000 claims description 18
- 230000003746 surface roughness Effects 0.000 claims description 18
- 239000002887 superconductor Substances 0.000 claims description 14
- 238000005240 physical vapour deposition Methods 0.000 claims description 13
- 239000010408 film Substances 0.000 description 58
- 238000000034 method Methods 0.000 description 32
- 238000004544 sputter deposition Methods 0.000 description 30
- 238000000137 annealing Methods 0.000 description 15
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 14
- 230000015572 biosynthetic process Effects 0.000 description 14
- 239000001301 oxygen Substances 0.000 description 14
- 229910052760 oxygen Inorganic materials 0.000 description 14
- 238000009792 diffusion process Methods 0.000 description 12
- 239000002245 particle Substances 0.000 description 11
- 239000010949 copper Substances 0.000 description 9
- 230000006641 stabilisation Effects 0.000 description 9
- 238000011105 stabilization Methods 0.000 description 9
- 239000010409 thin film Substances 0.000 description 9
- 238000010884 ion-beam technique Methods 0.000 description 8
- 230000002093 peripheral effect Effects 0.000 description 8
- 230000007547 defect Effects 0.000 description 7
- 238000010586 diagram Methods 0.000 description 7
- 238000007735 ion beam assisted deposition Methods 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 238000001704 evaporation Methods 0.000 description 5
- 230000008020 evaporation Effects 0.000 description 5
- 239000007769 metal material Substances 0.000 description 5
- 229910052761 rare earth metal Inorganic materials 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 239000011247 coating layer Substances 0.000 description 4
- 239000000470 constituent Substances 0.000 description 4
- 238000000151 deposition Methods 0.000 description 4
- 238000007747 plating Methods 0.000 description 4
- 230000002265 prevention Effects 0.000 description 4
- 150000002910 rare earth metals Chemical class 0.000 description 4
- 238000001953 recrystallisation Methods 0.000 description 4
- 230000000087 stabilizing effect Effects 0.000 description 4
- 229910000881 Cu alloy Inorganic materials 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910000856 hastalloy Inorganic materials 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 230000001681 protective effect Effects 0.000 description 3
- 239000002356 single layer Substances 0.000 description 3
- 239000010935 stainless steel Substances 0.000 description 3
- 229910001220 stainless steel Inorganic materials 0.000 description 3
- 238000007740 vapor deposition Methods 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- 241000954177 Bangana ariza Species 0.000 description 2
- 229910000990 Ni alloy Inorganic materials 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000002950 deficient Effects 0.000 description 2
- 238000010894 electron beam technology Methods 0.000 description 2
- 238000000635 electron micrograph Methods 0.000 description 2
- 230000001747 exhibiting effect Effects 0.000 description 2
- 238000001659 ion-beam spectroscopy Methods 0.000 description 2
- 230000001678 irradiating effect Effects 0.000 description 2
- 238000010030 laminating Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000001552 radio frequency sputter deposition Methods 0.000 description 2
- 229910001404 rare earth metal oxide Inorganic materials 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 239000011800 void material Substances 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 229910001369 Brass Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910017518 Cu Zn Inorganic materials 0.000 description 1
- 229910017752 Cu-Zn Inorganic materials 0.000 description 1
- 229910002482 Cu–Ni Inorganic materials 0.000 description 1
- 229910017943 Cu—Zn Inorganic materials 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 229910052691 Erbium Inorganic materials 0.000 description 1
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 229910021193 La 2 O 3 Inorganic materials 0.000 description 1
- 229910017493 Nd 2 O 3 Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910018487 Ni—Cr Inorganic materials 0.000 description 1
- 208000012868 Overgrowth Diseases 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000011362 coarse particle Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- TVZPLCNGKSPOJA-UHFFFAOYSA-N copper zinc Chemical compound [Cu].[Zn] TVZPLCNGKSPOJA-UHFFFAOYSA-N 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- 238000001755 magnetron sputter deposition Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 239000003870 refractory metal Substances 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 238000005477 sputtering target Methods 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
Description
本発明は酸化物超電導導体とその製造方法に関する。 The present invention relates to an oxide superconductor and a method for producing the same.
ＲＥ−１２３系の酸化物超電導体（ＲＥＢａ２Ｃｕ３Ｏ７−Ｘ：ＲＥはＹを含む希土類元素）は、液体窒素温度で超電導性を示し、電流損失が低いため、実用上極めて有望な素材とされており、これを線材に加工して電力供給用の導体あるいは電磁コイル等として使用することが要望されている。この酸化物超電導導体の一例構造として、機械的強度の高いテープ状の金属製の基材を用い、その表面にイオンビームアシスト成膜法（ＩＢＡＤ法）により結晶配向性の良好な中間薄膜を形成し、該中間薄膜の表面に成膜法により酸化物超電導層を形成し、その表面にＡｇなどの良導電材料からなる安定化層を形成した構造の酸化物超電導導体が知られている。 An RE-123-based oxide superconductor (REBa 2 Cu 3 O 7-X : RE is a rare earth element including Y) exhibits superconductivity at a liquid nitrogen temperature and has a low current loss. Therefore, it is an extremely promising material for practical use. It is desired to process this into a wire and use it as a power supply conductor or electromagnetic coil. As an example of the structure of this oxide superconducting conductor, an intermediate thin film with good crystal orientation is formed on the surface of a tape-shaped metal substrate with high mechanical strength by ion beam assisted film formation (IBAD method). An oxide superconducting conductor having a structure in which an oxide superconducting layer is formed on the surface of the intermediate thin film by a film forming method and a stabilizing layer made of a highly conductive material such as Ag is formed on the surface is known.
前記Ａｇの安定化層を形成するのは、酸化物超電導層に電流を流した際、外乱などにより超電導状態から常電導状態に転移することがあると、電流が不安定になることを避けるためである。このＡｇからなる安定化層を形成する場合、ＰＶＤ法（物理的気相合成法）により成膜されることが一般的である。
例えば、以下の特許文献１に、長尺のテープ状の基板の上に中間層を介し超電導層を形成後、銀のスパッタ層を形成し、更にそれら全体の周面を囲むようにＡｇの安定化層をめっきにより形成し、次いでＣｕの安定化層をめっきにより形成した積層構造の酸化物超電導導体が開示されている。
The stabilization layer of Ag is formed in order to prevent the current from becoming unstable when the current is passed through the oxide superconducting layer and the transition from the superconducting state to the normal conducting state may occur due to disturbance or the like. It is. In the case of forming a stabilization layer made of Ag, it is generally formed by a PVD method (physical vapor phase synthesis method).
For example, in Patent Document 1 below, after a superconducting layer is formed on a long tape-shaped substrate via an intermediate layer, a sputtered silver layer is formed, and Ag stability is further formed so as to surround the entire peripheral surface. An oxide superconducting conductor having a laminated structure is disclosed in which an oxide layer is formed by plating and then a Cu stabilization layer is formed by plating.
この特許文献１に開示されている酸化物超電導導体の構造において、Ａｇのスパッタ層はＡｇの安定化層の下地としてめっき液の侵食を防止するために設けられている。Ａｇのスパッタ層は、例えば、ＡｒプラズマによってＡｇのターゲットからはじき出したＡｇ粒子を基板上に付着させることで成膜される。
しかし、基板上に形成されたＡｇのスパッタ層には、成膜時の衝撃により、内部応力（残留応力）が働いているため、この内部応力が駆動力となって、拡散や再結晶が起こる。特に、酸化物超電導導体では、製造プロセス上、超電導層の結晶に酸素を供給するための５００℃程度の酸素アニールが必須であるため、酸素アニール時の熱によってひずみ（内部応力）が開放されることで、Ａｇの再結晶が発生し、結晶粒の粗大化やそれに伴うボイドの発生が見られる。
In the structure of the oxide superconducting conductor disclosed in Patent Document 1, an Ag sputter layer is provided as an underlayer for the Ag stabilizing layer to prevent the plating solution from eroding. The sputtered Ag layer is formed, for example, by depositing Ag particles ejected from the Ag target by Ar plasma on the substrate.
However, since internal stress (residual stress) is acting on the sputtered layer of Ag formed on the substrate due to impact during film formation, the internal stress acts as a driving force to cause diffusion and recrystallization. . In particular, in an oxide superconductor, oxygen annealing at about 500 ° C. for supplying oxygen to the crystal of the superconducting layer is essential in the manufacturing process, so strain (internal stress) is released by heat during oxygen annealing. As a result, recrystallization of Ag occurs, and the coarsening of crystal grains and the accompanying generation of voids are observed.
このため、Ａｇのスパッタ層では、再結晶や粗大化、ボイドの発生に起因するピンホールの発生が起こり、Ａｇのスパッタ層の劣化につながるおそれがあった。
Ａｇのスパッタ層にピンホールや劣化部分を生じていると、その上に形成されるめっき層の付きが悪くなり、酸化物超電導層を囲む構造にピンホールなどの欠陥を生じるおそれがある。上述の希土類系の酸化物超電導層の一部組成のものは、水分との反応性を有するものがあるので、酸化物超電導層が水分に曝されると、水酸化物等を生成して経時的に劣化することがあり、ピンホールや欠陥の無いＡｇの被覆層を得ることが課題とされている。
For this reason, in the sputtered layer of Ag, generation of pinholes due to recrystallization, coarsening, and generation of voids may occur, leading to deterioration of the sputtered layer of Ag.
If a pin hole or a deteriorated portion is formed in the Ag sputtered layer, the plating layer formed thereon becomes poor, and there is a possibility that a defect such as a pin hole is generated in the structure surrounding the oxide superconducting layer. Some of the rare earth oxide superconducting layers described above have reactivity with moisture, so when the oxide superconducting layer is exposed to moisture, it generates hydroxide and the like over time. It is a problem to obtain an Ag coating layer free from pinholes and defects.
本発明は、以上のような従来の実情に鑑みなされたものであり、酸化物超電導層の上にＡｇの保護層を被覆した積層構造の酸化物超電導導体において、ピンホールや欠陥部分の生じていない、樋密な構造のＡｇの保護層を形成した酸化物超電導導体の提供とその製造方法の提供を目的とする。 The present invention has been made in view of the conventional situation as described above, and in the oxide superconducting conductor having a laminated structure in which the protective layer of Ag is coated on the oxide superconducting layer, pinholes and defects are generated. An object is to provide an oxide superconducting conductor in which an Ag protective layer having a dense structure is formed and a method for producing the same.
本発明の酸化物超電導導体は、基材と、該基材の上方に設けられた配向層と酸化物超電導層とＡｇの保護層とを備えた酸化物超電導導体であって、前記Ａｇの保護層は、物理的蒸着法により、前記基材を２００℃〜８００℃の範囲に加熱しながら成膜されたものであり、前記Ａｇの保護層の表面粗さＲｚが１３００ｎｍ以下であることを特徴とする。
Ａｇの保護層の表面粗さＲｚが１３００ｎｍ以下であると、粗大な粒子やピンホールのない緻密な保護層を得ることができる。
この緻密で強固なＡｇの保護層であるならば、ボイドやピンホールなどの欠陥部分が少ないので、保護層で酸化物超電導層を覆った場合に露出部分を生じることがなく、酸化物超電導層に使用環境雰囲気から水分が浸入するおそれを少なくすることができる。
Oxide superconductor of the present invention is an oxide superconductor having a substrate and a an alignment layer provided over the substrate oxide superconducting layer and the Ag protective layer, protection of the Ag The layer is formed by physical vapor deposition while heating the base material in a range of 200 ° C. to 800 ° C., and the surface roughness Rz of the protective layer of Ag is 1300 nm or less. And
When the surface roughness Rz of the Ag protective layer is 1300 nm or less, a dense protective layer free from coarse particles and pinholes can be obtained.
If this dense and strong Ag protective layer is used, there are few defective parts such as voids and pinholes, so that when the oxide superconducting layer is covered with the protective layer, no exposed part is formed, and the oxide superconducting layer It is possible to reduce the risk of moisture entering from the ambient environment.
本発明の酸化物超電導導体は、前記Ａｇの保護層の結晶が前記酸化物超電導層の結晶に配向され、極点図において４回対称性を示すことを特徴とする請求項１または２に記載の酸化物超電導導体。
Ａｇの保護層の結晶が極点図において４回対称性を示すならば、Ａｇの保護層の結晶が酸化物超電導層の結晶に対し良好な整合性でもって結晶配向していることを意味するので、酸化物超電導層とＡｇの保護層との密着性が良好であり、酸化物超電導層に対して剥離する部分などのない良質のＡｇの保護層が得られる。
3. The oxide superconducting conductor according to claim 1, wherein the crystal of the protective layer of Ag is oriented to the crystal of the oxide superconducting layer and exhibits 4-fold symmetry in a pole figure. Oxide superconducting conductor.
If the crystal of the Ag protective layer shows fourfold symmetry in the pole figure, it means that the crystal of the Ag protective layer is crystal-oriented with good consistency with the crystal of the oxide superconducting layer. In addition, good adhesion between the oxide superconducting layer and the Ag protective layer is obtained, and a good quality Ag protective layer having no part peeled off from the oxide superconducting layer can be obtained.
本発明の酸化物超電導導体の製造方法は、基材の上方に配向層と酸化物超電導層を形成した後、酸化物超電導層上にＡｇの保護層を物理的蒸着法により形成する場合、基材を２００℃〜８００℃の範囲に加熱しながら成膜することにより、表面粗さＲｚが１３００ｎｍ以下のＡｇの保護層を形成することを特徴とする。
酸化物超電導層の上に２００〜８００℃で成膜することで、表面粗さＲｚが１３００ｎｍ以下であるＡｇの保護層を形成できるので、室温で成膜されたＡｇの保護層より緻密で強固な保護層で被覆した酸化物超電導層を備えた酸化物超電導導体を提供できる。
この緻密で強固なＡｇの保護層であるならば、ボイドやピンホールなどの欠陥部分が少ないので、保護層で酸化物超電導層を覆った場合に露出部分を生じることがなく、酸化物超電導層に使用環境雰囲気から水分が浸入するおそれを無くすることができる。
The method for producing an oxide superconducting conductor according to the present invention includes a method in which an alignment layer and an oxide superconducting layer are formed above a substrate, and then a protective layer of Ag is formed on the oxide superconducting layer by physical vapor deposition. An Ag protective layer having a surface roughness Rz of 1300 nm or less is formed by forming a film while heating the material in a range of 200 ° C. to 800 ° C.
By forming the film at 200 to 800 ° C. on the oxide superconducting layer, an Ag protective layer having a surface roughness Rz of 1300 nm or less can be formed. Therefore, it is denser and stronger than the Ag protective layer formed at room temperature. An oxide superconducting conductor having an oxide superconducting layer coated with a protective layer can be provided.
If this dense and strong Ag protective layer is used, there are few defective parts such as voids and pinholes, so that when the oxide superconducting layer is covered with the protective layer, no exposed part is formed, and the oxide superconducting layer It is possible to eliminate the risk of moisture entering from the ambient environment.
本発明の酸化物超電導導体の製造方法は、前記基材を４００〜８００℃の範囲に加熱しながら成膜することにより、表面粗さＲｚが１０１０ｎｍ以下のＡｇの保護層を形成することを特徴とする。
基材を４００〜８００℃に加熱しながら成膜することによりボイドやピンホールなどの欠陥部分が無い、より緻密なＡｇの保護層を酸化物超電導層上に形成できる。
In the method for producing an oxide superconducting conductor of the present invention, an Ag protective layer having a surface roughness Rz of 1010 nm or less is formed by forming a film while heating the substrate in a range of 400 to 800 ° C. And
By forming the film while heating the substrate to 400 to 800 ° C., a denser Ag protective layer free from defects such as voids and pinholes can be formed on the oxide superconducting layer.
本発明の酸化物超電導導体の製造方法は、前記Ａｇの保護層の結晶を前記酸化物超電導層の結晶に配向させ、極点図において４回対称性を示す保護層とすることを特徴とする。
Ａｇの保護層の結晶が極点図において４回対称性を示すならば、Ａｇの保護層の結晶が酸化物超電導層の結晶に対し良好な整合性でもって結晶配向していることを意味するので、酸化物超電導層とＡｇの保護層との密着性が良好であり、酸化物超電導層に対して剥離する部分などのない良質のＡｇの保護層が得られる。
The oxide superconducting conductor manufacturing method of the present invention is characterized in that the crystal of the protective layer of Ag is oriented to the crystal of the oxide superconducting layer to form a protective layer exhibiting 4-fold symmetry in the pole figure.
If the crystal of the Ag protective layer shows fourfold symmetry in the pole figure, it means that the crystal of the Ag protective layer is crystal-oriented with good consistency with the crystal of the oxide superconducting layer. In addition, good adhesion between the oxide superconducting layer and the Ag protective layer is obtained, and a good quality Ag protective layer having no part peeled off from the oxide superconducting layer can be obtained.
本発明により、ピンホールや欠陥部分の少ない緻密なＡｇの保護層を酸化物超電導層の上に被覆した酸化物超電導導体を提供できる。 According to the present invention, an oxide superconducting conductor in which a dense Ag protective layer with few pinholes and defects is coated on an oxide superconducting layer can be provided.
以下、本発明に係る酸化物超電導導体の実施形態について図面に基づいて説明する。
図１は本発明に係る第１実施形態の酸化物超電導導体１を模式的に示す概略断面図である。
この例の酸化物超電導導体１において、テープ状の基材２の上方に、下地層３と配向層４とキャップ層５と酸化物超電導層６と保護層７と安定化層８をこの順に積層して酸化物超電導積層体９が形成され、この酸化物超電導積層体９の周面を絶縁被覆層１０で覆って酸化物超電導導体１が構成されている。
Hereinafter, embodiments of an oxide superconducting conductor according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view schematically showing an oxide superconducting conductor 1 according to a first embodiment of the present invention.
In the oxide superconducting conductor 1 of this example, the base layer 3, the orientation layer 4, the cap layer 5, the oxide superconducting layer 6, the protective layer 7, and the stabilizing layer 8 are laminated in this order on the tape-shaped substrate 2. Thus, the oxide superconducting laminate 9 is formed, and the oxide superconducting conductor 1 is configured by covering the peripheral surface of the oxide superconducting laminate 9 with the insulating coating layer 10.
前記基材２は、通常の酸化物超電導導体の基材として使用することができ、高強度であれば良く、長尺のケーブルとするためにテープ状やシート状あるいは薄板状であることが好ましく、耐熱性の金属からなるものが好ましい。例えば、ハステロイ等のニッケル合金、銅合金、ステンレス鋼等の各種耐熱性金属材料、もしくはこれら各種金属材料上にセラミックスを配したもの、等が挙げられる。各種耐熱性金属の中でも、ニッケル合金が好ましい。なかでも、市販品であれば、ハステロイ（米国ヘインズ社製商品名）が好適であり、ハステロイとして、モリブデン、クロム、鉄、コバルト等の成分量が異なる、ハステロイＢ、Ｃ、Ｇ、Ｎ、Ｗ等のいずれの種類も使用できる。基材３の厚さは、目的に応じて適宜調整すれば良く、通常は、１０〜５００μｍの範囲とすることができる。 The base material 2 can be used as a base material for a normal oxide superconducting conductor and has only to have high strength, and is preferably in a tape shape, a sheet shape or a thin plate shape in order to obtain a long cable. Those made of heat-resistant metal are preferred. Examples thereof include various heat-resistant metal materials such as nickel alloys such as hastelloy, copper alloys, and stainless steel, or ceramics disposed on these various metal materials. Among various refractory metals, a nickel alloy is preferable. Especially, if it is a commercial item, Hastelloy (trade name made by US Haynes Co., Ltd.) is suitable. Any type can be used. What is necessary is just to adjust the thickness of the base material 3 suitably according to the objective, Usually, it can be set as the range of 10-500 micrometers.
下地層３は、以下に説明する拡散防止層とベッド層の複層構造あるいは、これらのうちどちらか１層からなる構造とすることができる。
下地層３として拡散防止層を設ける場合、拡散防止層は構成元素拡散を防止する目的あるいはその上に形成される他の層の膜質を改善するために形成されたもので、窒化ケイ素（Ｓｉ３Ｎ４）、酸化アルミニウム（Ａｌ２Ｏ３、「アルミナ」とも呼ぶ）、あるいは、ＧＺＯ（Ｇｄ２Ｚｒ２Ｏ７）等から構成される単層構造あるいは複層構造の層であることが望ましく、厚さは例えば１０〜４００ｎｍである。拡散防止層の厚さが１０ｎｍ未満となると、拡散防止層のみでは基材２の構成元素の拡散を十分に防止できなくなる虞がある。一方、拡散防止層の厚さが４００ｎｍを超えると、拡散防止層の内部応力が増大し、これにより、他の層を含めて全体が基材２から剥離しやすくなる虞がある。また、拡散防止層の結晶性は特に問われないので、通常のスパッタ法等の成膜法により形成すれば良い。
The underlayer 3 can have a multi-layer structure of a diffusion prevention layer and a bed layer, which will be described below, or a structure composed of one of these layers.
When a diffusion prevention layer is provided as the underlayer 3, the diffusion prevention layer is formed for the purpose of preventing the diffusion of constituent elements or for improving the film quality of other layers formed thereon. Silicon nitride (Si 3 N 4 ), aluminum oxide (Al 2 O 3 , also referred to as “alumina”), GZO (Gd 2 Zr 2 O 7 ), etc. The thickness is, for example, 10 to 400 nm. When the thickness of the diffusion preventing layer is less than 10 nm, there is a possibility that the diffusion of the constituent elements of the substrate 2 cannot be sufficiently prevented only by the diffusion preventing layer. On the other hand, when the thickness of the diffusion preventing layer exceeds 400 nm, the internal stress of the diffusion preventing layer increases, which may cause the whole including the other layers to be easily peeled off from the substrate 2. Further, since the crystallinity of the diffusion preventing layer is not particularly limited, it may be formed by a film forming method such as a normal sputtering method.
下地層３としてベッド層を設ける場合、ベッド層は、耐熱性が高く、界面反応性を低減するためのものであり、その上に配される膜の配向性を得るために用いる。このようなベッド層は、例えば、イットリア（Ｙ２Ｏ３）などの希土類酸化物であり、組成式（α１Ｏ２）２ｘ（β２Ｏ３）（１−ｘ）で示されるものが例示できる。より具体的には、Ｅｒ２Ｏ３、ＣｅＯ２、Ｄｙ２Ｏ３、Ｅｒ２Ｏ３、Ｅｕ２Ｏ３、Ｈｏ２Ｏ３、Ｌａ２Ｏ３等を例示することができ、これらの材料からなる単層構造あるいは複層構造でも良い。ベッド層は、例えばスパッタリング法等の成膜法により形成され、その厚さは例えば１０〜１００ｎｍである。また、ベッド層の結晶性は特に問われないので、通常のスパッタ法等の成膜法により形成すれば良い。
なお、下地層３は拡散防止層とベッド層の２層構造でも、これらのどちらかからなる単層構造でも良く、場合によっては下地層３を略しても良い。下地層３を略する場合は、基材２上に直接、以下に説明する配向層４が形成される。
When a bed layer is provided as the foundation layer 3, the bed layer has high heat resistance and is used for reducing interfacial reactivity, and is used for obtaining the orientation of a film disposed thereon. Such a bed layer is, for example, a rare earth oxide such as yttria (Y 2 O 3 ), and is exemplified by a compositional formula (α 1 O 2 ) 2x (β 2 O 3 ) (1-x). it can. More specifically, Er 2 O 3 , CeO 2 , Dy 2 O 3, Er 2 O 3 , Eu 2 O 3 , Ho 2 O 3 , La 2 O 3 and the like can be exemplified, and from these materials It may be a single layer structure or a multilayer structure. The bed layer is formed by a film forming method such as a sputtering method, and has a thickness of 10 to 100 nm, for example. Further, since the crystallinity of the bed layer is not particularly limited, it may be formed by a film forming method such as a normal sputtering method.
The underlayer 3 may be a two-layer structure including a diffusion prevention layer and a bed layer, or may be a single layer structure made of either of these layers. In some cases, the underlayer 3 may be omitted. When the base layer 3 is omitted, an alignment layer 4 described below is formed directly on the substrate 2.
配向層４は、単層構造あるいは複層構造のいずれでも良く、その上に積層されるキャップ層５の結晶配向性を制御するために以下に説明するＩＢＡＤ法により成膜され、２軸配向した結晶配向性の良好な薄膜から形成される。
一例として配向層４は、複数の結晶粒が粒界を介し接合された多結晶薄膜として構成され、各結晶粒の内部においては、それら結晶粒を構成する結晶が、それらの結晶軸のｃ軸を基材２の表面（あるいは下地層３の表面）に対し個々に垂直に向け、結晶軸のａ軸をほぼ一方向に揃えて（例えば結晶軸の分散の角度を所定の範囲に揃えて）配置されている。
The orientation layer 4 may be either a single layer structure or a multilayer structure, and is formed by the IBAD method described below to control the crystal orientation of the cap layer 5 laminated thereon, and is biaxially oriented. It is formed from a thin film with good crystal orientation.
As an example, the alignment layer 4 is configured as a polycrystalline thin film in which a plurality of crystal grains are joined via a grain boundary, and inside each crystal grain, the crystals constituting the crystal grains are c-axis of their crystal axes. Are oriented perpendicularly to the surface of the substrate 2 (or the surface of the underlayer 3), and the a axis of the crystal axes is aligned in almost one direction (for example, the angle of dispersion of the crystal axes is set within a predetermined range). Has been placed.
この配向層４をＩＢＡＤ（Ion-Beam-Assisted Deposition）法により良好な結晶配向性で成膜するならば、その上に形成するキャップ層５の結晶配向性を良好な値とすることができ、これによりキャップ層５の上に成膜する酸化物超電導層６の結晶配向性を良好なものとして、より優れた超電導特性を発揮できる酸化物超電導層６を得るようにすることができる。 If this alignment layer 4 is formed with a good crystal orientation by the IBAD (Ion-Beam-Assisted Deposition) method, the crystal orientation of the cap layer 5 formed thereon can be set to a good value. As a result, the oxide superconducting layer 6 formed on the cap layer 5 can be made to have good crystal orientation, and the oxide superconducting layer 6 that can exhibit more excellent superconducting characteristics can be obtained.
前記キャップ層５は、前記配向層５の表面に対してエピタキシャル成長し、その後、横方向（面方向）に粒成長（オーバーグロース）して、結晶粒が面内方向に選択成長するという過程を経て形成されたものが好ましい。このようなキャップ層５は、前記配向層４よりも高い面内配向度が得られる可能性がある。
キャップ層５の材質は、上記機能を発現し得るものであれば特に限定されないが、好ましいものとして具体的には、ＣｅＯ２、Ｙ２Ｏ３、Ａｌ２Ｏ３、Ｇｄ２Ｏ３、Ｚｒ２Ｏ３、Ｈｏ２Ｏ３、Ｎｄ２Ｏ３等が例示できる。キャップ層５の材質がＣｅＯ２である場合、キャップ層は、Ｃｅの一部が他の金属原子又は金属イオンで置換されたＣｅ−Ｍ−Ｏ系酸化物を含んでいても良い。
キャップ層５は、ＰＬＤ法（パルスレーザ蒸着法）、スパッタリング法等で成膜することができるが、大きな成膜速度を得られる点でＰＬＤ法を用いることが好ましい。ＰＬＤ法によるＣｅＯ２層の成膜条件としては、基材温度約５００〜１０００℃、約０．６〜１００Ｐａの酸素ガス雰囲気中で行うことができる。
ＣｅＯ２のキャップ層５の膜厚は、５０ｎｍ以上であればよいが、十分な配向性を得るには１００ｎｍ以上が好ましい。但し、厚すぎると結晶配向性が悪くなるので、５０〜５０００ｎｍの範囲、より好ましくは１００〜５０００ｎｍの範囲とすることができる。
The cap layer 5 is epitaxially grown on the surface of the alignment layer 5 and then undergoes a process of grain growth (overgrowth) in the lateral direction (plane direction), and crystal grains are selectively grown in the in-plane direction. Those formed are preferred. Such a cap layer 5 may have a higher in-plane orientation degree than the orientation layer 4.
The material of the cap layer 5 is not particularly limited as long as it can exhibit the above functions, but specific examples of preferable materials include CeO 2 , Y 2 O 3 , Al 2 O 3 , Gd 2 O 3 , and Zr 2. Examples thereof include O 3 , Ho 2 O 3 and Nd 2 O 3 . When the material of the cap layer 5 is CeO 2 , the cap layer may include a Ce—M—O-based oxide in which part of Ce is substituted with another metal atom or metal ion.
The cap layer 5 can be formed by a PLD method (pulse laser deposition method), a sputtering method, or the like, but it is preferable to use the PLD method from the viewpoint of obtaining a high film formation rate. The film formation conditions for the CeO 2 layer by the PLD method can be performed in an oxygen gas atmosphere at a substrate temperature of about 500 to 1000 ° C. and about 0.6 to 100 Pa.
The thickness of the CeO 2 cap layer 5 may be 50 nm or more, but is preferably 100 nm or more in order to obtain sufficient orientation. However, if it is too thick, the crystal orientation deteriorates, so that it can be in the range of 50 to 5000 nm, more preferably in the range of 100 to 5000 nm.
酸化物超電導層６は通常知られている組成の酸化物超電導体からなるものを広く適用することができ、ＲＥＢａ２Ｃｕ３Ｏ７−ｘ（ＲＥはＹ、Ｌａ、Ｎｄ、Ｓｍ、Ｅｒ、Ｇｄ等の希土類元素を表す）なる材質のもの、具体的には、Ｙ１２３（ＹＢａ２Ｃｕ３Ｏｙ）又はＧｄ１２３（ＧｄＢａ２Ｃｕ３Ｏｙ）を例示することができる。また、その他の酸化物超電導体、例えば、Ｂｉ２Ｓｒ２Ｃａｎ−１ＣｕｎＯ４＋２ｎ＋δなる組成等に代表される臨界温度の高い他の酸化物超電導体からなるものを用いても良いのは勿論である。
酸化物超電導層６は、スパッタ法、真空蒸着法、レーザ蒸着法、電子ビーム蒸着法等の物理的蒸着法（ＰＶＤ法）；化学気相成長法（ＣＶＤ法）；塗布熱分解法（ＭＯＤ法）等で積層できる。酸化物超電導層６の厚みは、０．５〜５μｍ程度であって、均一な厚みであることが好ましい。
The oxide superconducting layer 6 can be widely applied to an oxide superconductor having a generally known composition. REBa 2 Cu 3 O 7-x (RE is Y, La, Nd, Sm, Er, Gd For example, Y123 (YBa 2 Cu 3 O y ) or Gd123 (GdBa 2 Cu 3 O y ) can be exemplified. Further, other oxide superconductors, for example, Bi 2 Sr 2 Ca n- 1 Cu n for O 4 + 2n + δ becomes may be used in compositions such as those made of other oxide superconductors having high critical temperatures representative Of course.
The oxide superconducting layer 6 is formed by a physical vapor deposition method (PVD method) such as a sputtering method, a vacuum vapor deposition method, a laser vapor deposition method or an electron beam vapor deposition method; a chemical vapor deposition method (CVD method); a coating pyrolysis method (MOD method). ) And the like. The oxide superconducting layer 6 has a thickness of about 0.5 to 5 μm and preferably a uniform thickness.
酸化物超電導層６の上面を覆うように形成されている保護層７は、Ａｇからなり、スパッタ法などの物理的蒸着法（ＰＶＤ法）により成膜されている。保護層７の厚さは１〜３０μｍ程度とされている。本実施形態のＡｇの保護層７は、後述する如く望ましくは２００〜８００℃の高温で、より好ましくは４００〜８００℃の高温で成膜された緻密な薄膜であり、その表面粗さＲｚが１３００ｎｍ以下であり、より好ましくは１０１０ｎｍ以下の薄膜である。
本実施形態のＡｇの保護層７は、上述の如く高温でスパッタ法などの物理的蒸着法により成膜されている。上述の高温でスパッタした場合、スパッタ粒子のエネルギーが大きくなるために、スパッタ用のターゲットから酸化物超電導層６上に到達するときの勢いが室温で成膜する場合よりも大きい。そのため、室温での成膜よりも緻密で強固なＡｇの保護層７を酸化物超電導層６上に形成できる。上述の高温下でスパッタされたＡｇの粒子は酸化物超電導層６の上で堆積し結晶化する。
The protective layer 7 formed so as to cover the upper surface of the oxide superconducting layer 6 is made of Ag, and is formed by a physical vapor deposition method (PVD method) such as a sputtering method. The thickness of the protective layer 7 is about 1 to 30 μm. The Ag protective layer 7 of the present embodiment is a dense thin film formed at a high temperature of 200 to 800 ° C., more preferably at a high temperature of 400 to 800 ° C., as described later, and has a surface roughness Rz. It is 1300 nm or less, More preferably, it is a 1010 nm or less thin film.
The protective layer 7 of Ag of this embodiment is formed by a physical vapor deposition method such as a sputtering method at a high temperature as described above. When the sputtering is performed at the above-described high temperature, the energy of the sputtered particles increases, so that the momentum when reaching the oxide superconducting layer 6 from the sputtering target is larger than when the film is formed at room temperature. Therefore, a denser and stronger Ag protective layer 7 than the film formation at room temperature can be formed on the oxide superconducting layer 6. The Ag particles sputtered at a high temperature are deposited on the oxide superconducting layer 6 and crystallized.
この保護層７は、緻密なＡｇの薄膜であるので、アニールしても再結晶化し難く、表面の荒れやボイドの生成が抑制される。また、上述の高温下で成膜した薄膜ならば、熱によってスパッタ時にＡｇの内部に生じた残留応力による歪みを開放することが可能となる。例えば、加熱状態でスパッタ法により成膜した場合、成膜後に冷却すると酸化物超電導層６が基材１の上方に積層されていることから、基材１がある程度熱容量を有しているので、炉冷する冷却条件となり、アニール効果により保護層７を構成するＡｇの結晶において歪みの開放がなされる。
また、上述の温度範囲で高温成膜するならば、保護層７の下に位置する酸化物超電導層６に対し、ヘテロエピタキシャル成長した結晶配向性であって、正極点図において４回対称性を示すＡｇの保護層７が得られる。なお、Ａｇの結晶と希土類系の酸化物超電導層６との格子定数の差異は、約５％であるので、加熱成膜条件によってはヘテロエピタキシャル成長させ易いと考えられる。
Since this protective layer 7 is a dense Ag thin film, it is difficult to recrystallize even when annealed, and surface roughness and void formation are suppressed. In addition, in the case of the thin film formed at the above-described high temperature, it is possible to release the distortion due to the residual stress generated inside Ag during sputtering by heat. For example, when the film is formed by sputtering in a heated state, since the oxide superconducting layer 6 is laminated above the base material 1 when cooled after the film formation, the base material 1 has a certain heat capacity. Under the cooling condition for furnace cooling, strain is released in the Ag crystal constituting the protective layer 7 by the annealing effect.
Further, if the film is formed at a high temperature within the above-described temperature range, the crystal orientation is heteroepitaxially grown with respect to the oxide superconducting layer 6 located under the protective layer 7 and exhibits fourfold symmetry in the positive electrode diagram. A protective layer 7 of Ag is obtained. Note that the difference in lattice constant between the Ag crystal and the rare earth-based oxide superconducting layer 6 is about 5%, so it is considered that heteroepitaxial growth is likely to occur depending on the heating film formation conditions.
安定化層８は、良導電性の金属材料からなり、酸化物超電導層６が超電導状態から常電導状態に遷移しようとした時に、Ａｇの保護層７とともに、酸化物超電導層６の電流が転流するバイパスとして機能する。安定化層８を構成する金属材料としては、良導電性を有するものであればよく、特に限定されないが、銅、黄銅（Ｃｕ−Ｚｎ合金）、Ｃｕ−Ｎｉ合金等の銅合金、ステンレス等の比較的安価な材質からなるものを用いることが好ましく、中でも高い導電性を有し、安価であることがら銅合金製が好ましい。なお、酸化物超電導導体１を超電導限流器に使用する場合、安定化層８は高抵抗金属材料より構成され、Ｎｉ−Ｃｒ等のＮｉ系合金などを使用できる。
安定化層８の厚さは特に限定されず、適宜調整可能であるが、１０〜３００μｍとすることが好ましい。
前記被覆層１０は、樹脂絶縁層からなり、酸化物超電導積層体９の外周面に絶縁テープを巻回するなどの手段により酸化物超電導積層体９の全周を覆うように形成されている。
The stabilization layer 8 is made of a highly conductive metal material. When the oxide superconducting layer 6 is about to transition from the superconducting state to the normal conducting state, the current of the oxide superconducting layer 6 is converted together with the protective layer 7 of Ag. It functions as a bypass to flow. The metal material constituting the stabilization layer 8 is not particularly limited as long as it has good conductivity, but copper alloy such as copper, brass (Cu—Zn alloy), Cu—Ni alloy, stainless steel, etc. It is preferable to use a material made of a relatively inexpensive material. Among them, a copper alloy is preferable because it has high conductivity and is inexpensive. When the oxide superconducting conductor 1 is used for a superconducting fault current limiter, the stabilization layer 8 is made of a high resistance metal material, and a Ni-based alloy such as Ni—Cr can be used.
The thickness of the stabilization layer 8 is not particularly limited and can be adjusted as appropriate, but is preferably 10 to 300 μm.
The covering layer 10 is made of a resin insulating layer, and is formed so as to cover the entire circumference of the oxide superconducting laminate 9 by means such as winding an insulating tape around the outer peripheral surface of the oxide superconducting laminate 9.
前記構造の酸化物超電導導体１に設けられるＩＢＡＤ法による配向層４は、例えばターゲットにイオンビームを照射してターゲットの構成粒子を叩き出すか蒸発させて基材上に飛来させて堆積させるとともに、基材に対し所定の入射角度でアシスト用のイオンビームを照射するイオンビームアシストスパッタ装置で形成できる。
基材２が長尺のテープ状の場合は、イオンビームアシストスパッタ装置の内部において基材２を供給リールから巻取リール側に移動させている間に上述のイオンビームアシストスパッタ装置により成膜することができる。
The alignment layer 4 provided by the IBAD method provided on the oxide superconductor 1 having the above-described structure is deposited, for example, by irradiating the target with an ion beam to knock out or evaporate the constituent particles of the target to fly onto the substrate. It can be formed by an ion beam assist sputtering apparatus that irradiates an ion beam for assisting at a predetermined incident angle with respect to the substrate.
When the substrate 2 is in the form of a long tape, the film is formed by the above-described ion beam assisted sputtering apparatus while the substrate 2 is moved from the supply reel to the take-up reel inside the ion beam assisted sputtering apparatus. be able to.
以上説明のように、下地層３の表面に、ターゲットの構成粒子を堆積させつつ、所定の入射角度でイオン照射を行うことにより、形成されるスパッタ膜の特定の結晶軸がイオンの入射方向に固定され、結晶のｃ軸が金属基板の表面に対して垂直方向に配向するとともに、結晶のａ軸どうし（あるいはｂ軸どうし）が面内において一定方向に配向する（２軸配向する）中間薄膜としての配向層４を得ることができる。
このため、ＩＢＡＤ法によって下地層３上に形成された配向層４は、高い面内配向度を示す。
As described above, by irradiating ions at a predetermined incident angle while depositing the target constituent particles on the surface of the base layer 3, the specific crystal axis of the formed sputtered film is in the ion incident direction. An intermediate thin film in which the c-axis of the crystal is oriented in a direction perpendicular to the surface of the metal substrate, and the a-axes (or b-axes) of the crystal are oriented in a certain direction (biaxial orientation) in the plane. The alignment layer 4 can be obtained.
For this reason, the alignment layer 4 formed on the underlayer 3 by the IBAD method exhibits a high degree of in-plane alignment.
次に、前述のように、良好な配向性を有する配向層４の上にキャップ層５を形成していると、キャップ層５も良好な配向性を得ることができるとともに、そのキャップ層５上に酸化物超電導層６を形成すると、酸化物超電導層６もキャップ層５の配向性に整合するように結晶化する。よって前記キャップ層５上に形成された酸化物超電導層６は、結晶配向性に乱れが殆どなく、この酸化物超電導層６を構成する結晶粒の１つ１つにおいては、基材２の厚さ方向に電気を流しにくいｃ軸が配向し、基材２の長さ方向にａ軸どうしあるいはｂ軸どうしが配向している（２軸配向している）。このように良好な結晶配向性でもって形成された希土類系の酸化物超電導層６が良好な結晶配向性であるならば、正極点図において４回対称性を示す。
従って得られた酸化物超電導層６は、結晶粒界における量子的結合性に優れ、結晶粒界における超電導特性の劣化が殆どないので、基材２の長さ方向に電気を流し易くなり、十分に高い臨界電流が得られる。
Next, as described above, when the cap layer 5 is formed on the orientation layer 4 having a good orientation, the cap layer 5 can also obtain a good orientation, and on the cap layer 5. When the oxide superconducting layer 6 is formed, the oxide superconducting layer 6 is also crystallized so as to match the orientation of the cap layer 5. Therefore, the oxide superconducting layer 6 formed on the cap layer 5 is hardly disturbed in crystal orientation, and in each of the crystal grains constituting the oxide superconducting layer 6, the thickness of the substrate 2 is reduced. The c-axis that hardly allows electricity to flow is oriented in the vertical direction, and the a-axis or the b-axis is oriented in the length direction of the substrate 2 (biaxially oriented). If the rare earth-based oxide superconducting layer 6 formed with such a good crystal orientation has a good crystal orientation, the positive electrode diagram shows fourfold symmetry.
Therefore, the obtained oxide superconducting layer 6 is excellent in quantum connectivity at the crystal grain boundary, and hardly deteriorates in the superconducting characteristics at the crystal grain boundary. High critical current can be obtained.
以上説明の如く形成された酸化物超電導導体１は、ＩＢＡＤ法により成膜された結晶配向性に優れた配向層４を備え、その上にキャップ層５を介し結晶配向性に優れた酸化物超電導層６を備えているので、優れた超電導特性を発揮する。
更に、本実施形態の酸化物超電導導体１であるならば、酸化物超電導層６の上に緻密でピンホールなどの欠陥の無いＡｇの保護層７を備えているので、酸化物超電導層６に対して水分の浸入し難い構造とすることができ、水分による劣化の生じ難い酸化物超電導導体１を提供できる。
The oxide superconducting conductor 1 formed as described above includes an orientation layer 4 having excellent crystal orientation formed by an IBAD method, and an oxide superconductor having excellent crystal orientation via a cap layer 5 thereon. Since the layer 6 is provided, excellent superconducting properties are exhibited.
Furthermore, in the case of the oxide superconducting conductor 1 of the present embodiment, the oxide superconducting layer 6 is provided with the Ag protective layer 7 which is dense and free from defects such as pinholes on the oxide superconducting layer 6. On the other hand, it is possible to provide a structure in which moisture hardly enters, and it is possible to provide the oxide superconducting conductor 1 which is not easily deteriorated by moisture.
ところで、本発明に係る酸化物超電導導体１において、保護層７の上に形成する安定化層８を略して構成することも可能である。一例として、図２に示す如く、テープ状の基材２の上方に、下地層３と配向層４とキャップ層５と酸化物超電導層６と保護層７を積層して酸化物超電導積層体１１を構成し、この酸化物超電導積層体１１の周面を絶縁被覆層１０で覆って酸化物超電導導体１２を構成しても良い。即ち、用途に応じて安定化層８を略した構造の酸化物超電導導体１２としても良い。 By the way, in the oxide superconductor 1 according to the present invention, the stabilization layer 8 formed on the protective layer 7 may be omitted. As an example, as shown in FIG. 2, an oxide superconducting laminate 11 is formed by laminating a base layer 3, an orientation layer 4, a cap layer 5, an oxide superconducting layer 6, and a protective layer 7 above a tape-like substrate 2. The oxide superconducting conductor 12 may be configured by covering the peripheral surface of the oxide superconducting laminate 11 with the insulating coating layer 10. In other words, the oxide superconducting conductor 12 may have a structure in which the stabilization layer 8 is omitted depending on the application.
次に、正極点図において４回対称性を示す結晶配向性を有するＡｇの保護層７を形成する手段の一例について以下に説明する。
図３は、酸化物超電導積層体９において酸化物超電導層６の上にＡｇの保護層７を形成する際に行う物理蒸着法（ＰＶＤ）に使用する成膜装置の一例を示すもので、この例の成膜装置２０は、真空ポンプなどに排気管２１を介し接続されて内部を真空排気可能に構成された成膜チャンバ２２と、この成膜チャンバ２２の内底部に設けられた蒸発源２３と、成膜チャンバ２２の中央部に設けられた回転ドラム２４とを備えて構成されている。回転ドラム２４は中空の肉厚の金属製とされている。
回転ドラム２４は内部に加熱ヒータ２５を備え、その外周面を目的の温度、例えば４００〜９００℃程度の温度に均一加熱できるように構成されている。この回転ドラム２４の外周面に基材２を巻き付けて固定できるように構成されている。
Next, an example of means for forming the protective layer 7 of Ag having a crystal orientation exhibiting 4-fold symmetry in the positive electrode diagram will be described below.
FIG. 3 shows an example of a film forming apparatus used for physical vapor deposition (PVD) performed when forming the protective layer 7 of Ag on the oxide superconducting layer 6 in the oxide superconducting laminate 9. An example film forming apparatus 20 includes a film forming chamber 22 connected to a vacuum pump or the like via an exhaust pipe 21 so that the inside can be evacuated, and an evaporation source 23 provided at the inner bottom of the film forming chamber 22. And a rotating drum 24 provided at the center of the film forming chamber 22. The rotary drum 24 is made of a hollow and thick metal.
The rotating drum 24 includes a heater 25 inside, and is configured so that the outer peripheral surface thereof can be uniformly heated to a target temperature, for example, a temperature of about 400 to 900 ° C. The base material 2 can be wound around and fixed to the outer peripheral surface of the rotating drum 24.
本実施形態では、基材２の上に下地層３と配向層４とキャップ層５と酸化物超電導層６を形成した積層体２６が酸化物超電導層６側を表にして図３に示す如く必要長さ螺旋状に回転ドラム２４の周面に巻き付けられている。
蒸発源２３は、ＰＶＤ装置に応じて種々の態様をとることができ、例えば、スパッタ系であれば、ＤＣあるいはＲＦスパッタリング、マグネトロンスパッタリング、イオンビームスパッタリング、ＥＣＲ（Electron Cyclotron Resonance）スパッタリング等であり、蒸発系であれば、抵抗加熱式、電子ビーム加熱式、高周波誘導加熱式、レーザービーム加熱式のいずれかを適宜採用できる。 ＤＣあるいはＲＦスパッタ方式の蒸発源２３として例えば、０．１〜２Ｐａ程度の減圧雰囲気に調整して成膜できる。
In the present embodiment, a laminated body 26 in which the base layer 3, the alignment layer 4, the cap layer 5, and the oxide superconducting layer 6 are formed on the substrate 2 is shown with the oxide superconducting layer 6 side as a table as shown in FIG. It is wound around the peripheral surface of the rotary drum 24 in a spiral shape with a required length.
The evaporation source 23 can take various modes depending on the PVD apparatus. For example, in the case of a sputtering system, DC or RF sputtering, magnetron sputtering, ion beam sputtering, ECR (Electron Cyclotron Resonance) sputtering, etc. As long as it is an evaporation system, any one of a resistance heating type, an electron beam heating type, a high frequency induction heating type, and a laser beam heating type can be used as appropriate. As the evaporation source 23 of the DC or RF sputtering method, for example, the film can be formed by adjusting to a reduced pressure atmosphere of about 0.1 to 2 Pa.
図３に示す成膜装置２０によりＡｇの保護層７を成膜するには、成膜チャンバ２２の内部を上述の減圧雰囲気に調節し、積層体２６を巻き付けた回転ドラム２４を所望の温度、例えば２００〜８００℃に加熱しつつ回転させながら、蒸発源２３からＡｇの粒子を回転ドラム２４側に飛ばすことで、回転ドラム２４に巻き付けた積層体２６の酸化物超電導層６上に保護層７を成膜することができる。
この成膜の場合、回転ドラム２４に内蔵されているヒータ２５に通電して回転ドラム２４の外周面の温度を４００〜８００℃の範囲に設定して成膜することがより好ましい。
この温度範囲で成膜することにより、Ａｇの粒子に望ましい粒子エネルギーを付与することができ、酸化物超電導層６の上において結晶化し易く、緻密なＡｇの保護層７を形成できる。この温度範囲で成膜したＡｇの保護膜７であるならば、結晶化したＡｇの保護層７とすることができ、再結晶し難く、ボイドの生成を抑制した保護膜７を得ることができる。
In order to form the Ag protective layer 7 by the film forming apparatus 20 shown in FIG. 3, the inside of the film forming chamber 22 is adjusted to the above-described reduced-pressure atmosphere, and the rotating drum 24 around which the laminated body 26 is wound has a desired temperature, For example, the protective layer 7 is formed on the oxide superconducting layer 6 of the laminated body 26 wound around the rotating drum 24 by flying Ag particles from the evaporation source 23 toward the rotating drum 24 while rotating while heating at 200 to 800 ° C. Can be formed.
In the case of this film formation, it is more preferable to energize the heater 25 built in the rotating drum 24 and set the temperature of the outer peripheral surface of the rotating drum 24 within a range of 400 to 800 ° C.
By forming a film in this temperature range, desirable particle energy can be imparted to the Ag particles, and it is easy to crystallize on the oxide superconducting layer 6 and a dense Ag protective layer 7 can be formed. If it is the protective film 7 of Ag formed in this temperature range, it can be set as the protective layer 7 of crystallized Ag, and it can be hard to recrystallize and the protective film 7 which suppressed generation | occurrence | production of a void can be obtained. .
また、必要な膜厚の保護層７を成膜後、成膜チャンバ２２の内部において回転ドラム２４を冷却する場合、回転ドラム２４は肉厚の金属製であり、積層体２６より遙かに大きな熱容量を有するので、保護層７は薄くとも急冷されることはなく、回転ドラム２４とともに徐冷される。このため、成膜後のＡｇの保護層７を炉令した状態とすることができ、アニールした場合と同等のアニール効果を得ることができる。
上述の如く２００〜８００℃の高温に加熱した酸化物超電導層６の上にＡｇの粒子をスパッタにより堆積させるとＡｇの表面粗さＲｚを１３００ｎｍ以下にすることができるが、更に適切な温度（４００〜８００℃）で成膜すると、表面粗さＲｚを１０１０ｎｍ以下にできるとともに、下地の酸化物超電導層６に対しヘテロエピタキシャル成長した緻密なＡｇの配向層７を得ることができる。Ａｇの結晶格子と希土類系の酸化物超電導層６との格子の格子定数の差はおよそ５％であるので、上述の４００〜８００℃で成膜することで、ヘテロエピタキシャル成長させ易い効果がある。更に好ましくは、積層体２６を５００〜８００℃で加熱してスパッタすることにより表面粗さＲｚを４３０ｎｍ以下とすることができ、より水分による劣化が生じ難い酸化物超電導導体を提供することができる。
Further, when the rotating drum 24 is cooled in the film forming chamber 22 after the protective layer 7 having a required thickness is formed, the rotating drum 24 is made of a thick metal and is much larger than the laminate 26. Since it has a heat capacity, the protective layer 7 is not rapidly cooled even if it is thin, and is gradually cooled together with the rotating drum 24. For this reason, the protective layer 7 of Ag after film formation can be in a state of being subjected to a furnace, and an annealing effect equivalent to that obtained when annealing can be obtained.
As described above, when Ag particles are deposited on the oxide superconducting layer 6 heated to a high temperature of 200 to 800 ° C. by sputtering, the surface roughness Rz of Ag can be reduced to 1300 nm or less. When the film is formed at 400 to 800 ° C., the surface roughness Rz can be reduced to 1010 nm or less, and the dense Ag alignment layer 7 heteroepitaxially grown on the underlying oxide superconducting layer 6 can be obtained. Since the difference in lattice constant between the Ag crystal lattice and the rare earth-based oxide superconducting layer 6 is about 5%, forming the film at 400 to 800 ° C. has an effect of facilitating heteroepitaxial growth. More preferably, the surface roughness Rz can be reduced to 430 nm or less by heating and laminating the laminate 26 at 500 to 800 ° C., and an oxide superconducting conductor that is less likely to be deteriorated by moisture can be provided. .
以上説明の如く、ヘテロエピタキシャル成長したＡｇの保護層７は、酸化物超電導層６の上に緻密でピンホールなどの欠陥の無いＡｇの保護層７となっており、さらに、酸化物超電導層６に対し密着性においても優れているので、酸化物超電導層６に対し水分が浸入し難い構造とすることができ、水分による劣化の生じ難い酸化物超電導導体１を提供できる。 As described above, the Ag protective layer 7 heteroepitaxially grown is a dense Ag protective layer 7 having no defects such as pinholes on the oxide superconducting layer 6. On the other hand, since the adhesiveness is also excellent, it is possible to provide a structure in which moisture does not easily enter the oxide superconducting layer 6, and it is possible to provide the oxide superconducting conductor 1 in which deterioration due to moisture hardly occurs.
ハステロイＣ２７６（米国ヘインズ社商品名）からなる幅１０ｍｍ、厚さ０.１ｍｍ、長さ１０００ｍｍのテープ状の表面平滑な基材を用意し、表面を洗浄してからイオンビームアシストスパッタ法を用い、１．２μｍ厚のＧｄ２Ｚｒ２Ｏ７（ＧＺＯ；中間層）を形成した上に、パルスレーザー蒸着法（ＰＬＤ法）により１．０μｍ厚のＣｅＯ２（キャップ層）を成膜した。次いでＣｅＯ２層上にＰＬＤ法により１．０μｍ厚のＧｄＢａ２Ｃｕ３Ｏ７−ｘ（酸化物超電導層）を形成した。 Prepare a tape-like surface-smooth base material having a width of 10 mm, a thickness of 0.1 mm, and a length of 1000 mm made of Hastelloy C276 (trade name of Haynes, USA), and using an ion beam assisted sputtering method after cleaning the surface, A 1.2 μm thick Gd 2 Zr 2 O 7 (GZO; intermediate layer) was formed, and then a 1.0 μm thick CeO 2 (cap layer) was formed by a pulse laser deposition method (PLD method). Next, GdBa 2 Cu 3 O 7-x (oxide superconducting layer) having a thickness of 1.0 μm was formed on the CeO 2 layer by the PLD method.
次に、Ａｇのターゲットを用い、酸化物超電導層上に以下の表１に記載する温度でイオンビームスパッタ法により厚さ８μｍのＡｇの保護層を形成した。このＡｇの保護層を形成する場合、図３に示す成膜チャンバに備えたスレンレス鋼製の回転ドラムに酸化物超電導層側を表にして巻き付け、成膜チャンバの内部を０．５Ｐａに減圧し、回転ドラムの回転速度を４９０ｒｐｍに設定して成膜した。
回転ドラムによる基板の加熱温度条件を以下の表１に示す如く１００℃、２００℃、３００℃、４００℃、５００℃、８００℃、９００℃の各値とした。また、比較例１は３０℃で成膜した例である。なお、３００℃、４００℃、５００℃、８００℃、９００℃で成膜した例については、スパッタ終了後、基材温度が２００℃以下になるまで真空状態を保持し、次いで５００℃の酸素雰囲気中に５時間保持し、酸素アニール処理を施し、炉冷した。
この温度履歴で基材は回転ドラムと共に冷却されるので、徐冷される。
Next, an Ag protective layer having a thickness of 8 μm was formed on the oxide superconducting layer by an ion beam sputtering method at a temperature shown in Table 1 below using an Ag target. When forming this protective layer of Ag, the oxide superconducting layer side is wound around a rotating drum made of stainless steel provided in the film forming chamber shown in FIG. 3, and the inside of the film forming chamber is decompressed to 0.5 Pa. The film was formed with the rotational speed of the rotating drum set to 490 rpm.
As shown in Table 1 below, the heating temperature condition of the substrate by the rotating drum was set to values of 100 ° C., 200 ° C., 300 ° C., 400 ° C., 500 ° C., 800 ° C., and 900 ° C. Comparative Example 1 is an example in which a film was formed at 30 ° C. Note that, for the examples where the film was formed at 300 ° C., 400 ° C., 500 ° C., 800 ° C., and 900 ° C., after sputtering, the vacuum state was maintained until the substrate temperature became 200 ° C. or lower, and then the oxygen atmosphere at 500 ° C. It was kept for 5 hours, subjected to oxygen annealing treatment, and cooled in the furnace.
Since the substrate is cooled together with the rotating drum by this temperature history, it is gradually cooled.
得られた各酸化物超電導導体の試料について、ＦＥ−ＳＥＭ（電界放射型走査電子顕微鏡）による表面の粒径測定、ＦＩＢ（集束イオンビーム）による断面加工を行いＳＩＭ（走査イオン顕微鏡）による断面観察を行った。
得られた各試料のＡｇの保護層について、表面粗さを接触式表面粗さ測定器にてｎ＝１０の平均値をとって計測した（十点表面平均粗さ：Ｒｚ）。以上の結果を表１に示す。表１に示すスパッタ温度は、スパッタ時の基板温度、換言すると、スパッタ時の積層体温度を意味する。
The obtained oxide superconducting conductor samples were subjected to surface particle size measurement by FE-SEM (field emission scanning electron microscope), cross-section processing by FIB (focused ion beam), and cross-section observation by SIM (scanning ion microscope). Went.
About the protective layer of Ag of each obtained sample, the surface roughness was measured by taking an average value of n = 10 with a contact type surface roughness measuring instrument (ten-point surface average roughness: Rz). The results are shown in Table 1. The sputtering temperature shown in Table 1 means the substrate temperature during sputtering, in other words, the laminate temperature during sputtering.
図４に表１の比較例１（ヒーター未使用：３０℃）の試料の酸素アニール処理前の組織写真と酸素アニール後の組織写真を示す。また、図４に表１の試験例４の試料の酸素アニール処理前後の組織写真と試験例５の試料の酸素アニール処理前後の組織写真を示す。各組織写真の左下に表記されているＨ型の縮尺は２μｍを示す。
また、図５に、得られた各試験例のＡｇの保護膜におけるスパッタ温度と表面の十点平均粗さ（Ｒｚ）について、酸素アニール前後の値を示す。
図５に示す関係から、スパッタ温度（成膜時の基材温度）について、５００℃とした試料において、酸素アニール前後の十点表面平均粗さの値がほぼ同じ値を示した。これは、酸素アニールにより５００℃に加熱しても、Ａｇの再結晶による結晶粒径の粗大化が起こっていないことを示す。
FIG. 4 shows a structure photograph before oxygen annealing treatment and a structure photograph after oxygen annealing of the sample of Comparative Example 1 (heater not used: 30 ° C.) in Table 1. 4 shows a structure photograph before and after the oxygen annealing treatment of the sample of Test Example 4 in Table 1 and a structure photograph of the sample of Test Example 5 before and after the oxygen annealing treatment. The scale of the H type indicated on the lower left of each tissue photograph is 2 μm.
FIG. 5 shows values before and after oxygen annealing for the sputtering temperature and the 10-point average roughness (Rz) of the surface of the Ag protective film obtained in each test example.
From the relationship shown in FIG. 5, the 10-point surface average roughness values before and after the oxygen annealing showed substantially the same value in the sample with the sputtering temperature (base material temperature during film formation) set to 500 ° C. This indicates that the crystal grain size is not coarsened by recrystallization of Ag even when heated to 500 ° C. by oxygen annealing.
図６にヒータにより５００℃加熱した際に得られた試料の断面写真を示し、図７にヒーター未使用時（３０℃）に得られた試料の断面写真を示す。
図６と図７に示すように基板上に中間層とＧｄＢＣＯ（Ｇｄ１Ｂａ２Ｃｕ３Ｏ７−ｘ）層が積層され、その上にＡｇの保護層が積層されている状態を把握できる。Ａｇの保護層の表面の粗い図７の試料ではＡｇの保護層の内部に粒子の粗大化により複数の空隙が形成されている。これに対し５００℃で成膜している図６の試料では空隙が形成されておらず、緻密なＡｇの保護層が得られている。なお、成膜温度を８００℃より更に上げて、９００℃で成膜した試料では、酸化物超電導層が中間層と反応し、超電導特性が劣化した。このため、９００℃でＡｇの保護層を成膜することは超電導特性が劣化するので好ましくない。
FIG. 6 shows a cross-sectional photograph of the sample obtained when heated at 500 ° C. by the heater, and FIG. 7 shows a cross-sectional photograph of the sample obtained when the heater is not used (30 ° C.).
As shown in FIGS. 6 and 7, it is possible to grasp a state in which an intermediate layer and a GdBCO (Gd 1 Ba 2 Cu 3 O 7-x ) layer are stacked on a substrate and an Ag protective layer is stacked thereon. In the sample of FIG. 7 where the surface of the Ag protective layer is rough, a plurality of voids are formed in the Ag protective layer due to the coarsening of the particles. On the other hand, in the sample of FIG. 6 formed at 500 ° C., voids are not formed, and a dense Ag protective layer is obtained. Note that in the sample formed at 900 ° C. with the film formation temperature further raised from 800 ° C., the oxide superconducting layer reacted with the intermediate layer, and the superconducting characteristics deteriorated. For this reason, it is not preferable to form an Ag protective layer at 900 ° C., because the superconducting properties deteriorate.
表１と図４、図５、図６、図７の関係を勘案すると、スパッタ温度（成膜温度）が４００℃の試料と５００℃の試料と８００℃の試料であれば表面粗さＲｚ１０１０μｍ以下であり、下地の酸化物超電導層に対してＡｇの配向層が結晶配向し、緻密なＡｇの保護層が得られている。
また、３０℃と１００℃で成膜した試料に対し、２００℃で成膜した試料の方が十点表面平均粗さＲｚの値が良好となっている。
以上の結果から、Ａｇの保護層において緻密で表面の平滑な試料を得るためには、基材を２００℃以上に加熱して成膜することが有効であることがわかる。また、５００℃で行う酸素アニール後において、十点表面平均粗さＲｚの値を１３００ｎｍ以下とするとともに、超電導特性の劣化も引き起こさないためには、２００〜８００℃に基材を加熱して成膜することが望ましいことも分かる。
Considering the relationship between Table 1 and FIG. 4, FIG. 5, FIG. 6, and FIG. 7, if the sputtering temperature (film formation temperature) is 400 ° C., 500 ° C., and 800 ° C., the surface roughness is Rz 1010 μm or less. Thus, the Ag orientation layer is crystallized with respect to the underlying oxide superconducting layer, and a dense Ag protective layer is obtained.
In addition, the sample formed at 200 ° C. has a better 10-point surface average roughness Rz than the samples formed at 30 ° C. and 100 ° C.
From the above results, it can be seen that it is effective to form a film by heating the substrate to 200 ° C. or higher in order to obtain a dense and smooth sample in the protective layer of Ag. In addition, after the oxygen annealing performed at 500 ° C., the 10-point surface average roughness Rz is set to 1300 nm or less and the base material is heated to 200 to 800 ° C. in order not to cause deterioration of the superconducting characteristics. It can also be seen that filming is desirable.
次に、図８は表１の試験例３（スパッタ温度３００℃）で得られたＡｇの保護層の正極点図を示し、図９は表１の試験例５（スパッタ温度５００℃）で得られたＡｇの保護層の正極点図を示し、図１０は比較例１（スパッタ温度３０℃）で得られたＡｇの保護層の正極点図を示す。
また、正極点図からスパッタ温度３００℃の試料と５００℃の試料において４回対称性が認められる。図８においては３０゜、１２０゜、２１０゜、３００゜の位置に、図９においては０゜、９０゜、１８０゜、２７０゜の位置にそれぞれ４回対称性を示す図形が得られている。
更に、表１に示す表面粗さＲｚは３００〜９００℃において小さくなり、更に配向性に優れる傾向となることから勘案すると、３００℃〜９００℃成膜において得られたＡｇの保護層は４回対称性が認められることが明らかである。このため、Ａｇの保護層において下地の酸化物超電導層に対しエピタキシャル成長している保護層を得るためには、スパッタ温度として３００〜９００℃の範囲を選択することが望ましいことも判明した。
Next, FIG. 8 is a positive electrode diagram of the protective layer of Ag obtained in Test Example 3 (Sputtering temperature 300 ° C.) in Table 1, and FIG. 9 is obtained in Test Example 5 (Sputtering temperature 500 ° C.) of Table 1. FIG. 10 shows a positive electrode point diagram of the protective layer of Ag obtained in Comparative Example 1 (sputtering temperature 30 ° C.).
In addition, a four-fold symmetry is observed in the sample having a sputtering temperature of 300 ° C. and the sample having a temperature of 500 ° C. from the positive electrode diagram. In FIG. 8, four-fold symmetry figures are obtained at 30 °, 120 °, 210 ° and 300 ° positions, and in FIG. 9 at 0 °, 90 °, 180 ° and 270 ° positions. .
Furthermore, considering that the surface roughness Rz shown in Table 1 decreases at 300 to 900 ° C. and tends to be more excellent in orientation, the protective layer of Ag obtained in film formation at 300 to 900 ° C. is 4 times. It is clear that symmetry is observed. For this reason, in order to obtain the protective layer epitaxially grown with respect to the base oxide superconducting layer in the protective layer of Ag, it was also found that it is desirable to select a range of 300 to 900 ° C. as the sputtering temperature.
次に、各酸化物超電導導体試料について、温度１２０℃、湿度１００％、圧力２気圧の雰囲気中に保持するプレッシャークッカー試験を行い、試験時間２４時間経過後、４８時間経過後、７２時間経過後の各試料の液体窒素温度（７７Ｋ）における臨界電流値Ｉｃを測定した。各試料について、プレッシャークッカー試験前の臨界電流値Ｉｃ０に対して試験後の臨界電流値Ｉｃの割合（Ｉｃ／Ｉｃ０×１００（％））を算出し、得られた結果を図１１に記載する。
図１１に示す結果から、３０℃、１００℃で成膜した試料に対し、２００℃、更には４００℃、５００℃で成膜した試料の方が明らかに試験結果に優れている。なお、このプレッシャークッカー試験は水分の影響を受けやすいと認識されている希土類系の積層構造の酸化物超電導導体にとって過酷な加速試験の一種であり、Ｉｃ／Ｉｃ０の値が低下するから酸化物超電導導体として不適であるとは単純に言えないが、耐水性に対する目安にはなる指標である。
このプレッシャークッカー試験の結果から見て、Ａｇの保護層が緻密で空洞などの無い試料の方が耐水性にも優れるので、耐水性の面からみて、Ａｇの保護層を２００℃以上、８００℃以下の高温で成膜する方が緻密な保護層を形成できており、４００℃以上、８００℃以下の温度範囲で成膜した保護層の方が耐水性の面でより優れていることが分かる。
更に、先に説明した表１と図５に示す試験結果も含めて総合的に勘案すると、積層体を５００〜８００℃に加熱して成膜することにより表面粗さＲｚは４３０ｎｍ以下と著しく小さくなり、プレッシャークッカー試験でのＩｃの低下も少ないことから、耐水性がより優れていることがわかるので、５００℃以上、８００℃以下に加熱しながら成膜することが最も好ましいと考えられる。
Next, each oxide superconducting conductor sample was subjected to a pressure cooker test held in an atmosphere of a temperature of 120 ° C., a humidity of 100%, and a pressure of 2 atm. After a test time of 24 hours, 48 hours, and 72 hours. The critical current value Ic at the liquid nitrogen temperature (77 K) of each sample was measured. For each sample, the ratio of the critical current value Ic after the test to the critical current value Ic0 before the pressure cooker test (Ic / Ic0 × 100 (%)) is calculated, and the obtained results are shown in FIG.
From the results shown in FIG. 11, the samples formed at 200 ° C., further 400 ° C., and 500 ° C. are clearly superior to the test results compared to the samples formed at 30 ° C. and 100 ° C. This pressure cooker test is a kind of harsh acceleration test for rare earth-based oxide superconducting conductors, which are recognized to be easily affected by moisture, and the value of Ic / Ic0 decreases, so that the oxide superconductivity is reduced. Although it cannot simply be said that it is unsuitable as a conductor, it is an index that serves as a measure for water resistance.
From the result of the pressure cooker test, a sample having a dense Ag protective layer and having no voids is superior in water resistance. From the viewpoint of water resistance, the Ag protective layer is 200 ° C. or higher and 800 ° C. It can be seen that a dense protective layer can be formed when the film is formed at the following high temperature, and that the protective layer formed at a temperature range of 400 ° C. or higher and 800 ° C. or lower is superior in terms of water resistance. .
Furthermore, when comprehensively including the test results shown in Table 1 and FIG. 5 described above, the surface roughness Rz is remarkably small at 430 nm or less by heating the laminated body to 500 to 800 ° C. to form a film. Thus, since the decrease in Ic in the pressure cooker test is small, it can be seen that the water resistance is more excellent. Therefore, it is considered most preferable to form a film while heating at 500 ° C. or higher and 800 ° C. or lower.
本発明は、例えば酸化物超電導送電線や超電導マグネット用のコイル巻線に利用することができる酸化物超電導導体を提供する。 The present invention provides an oxide superconducting conductor that can be used for, for example, an oxide superconducting power transmission line or a coil winding for a superconducting magnet.
１…酸化物超電導導体、２…基材、３…下地層、４…配向層、５…キャップ層、６…酸化物超電導層、７…保護層、８…安定化層、９…酸化物超電導積層体、１０…絶縁被覆層、１１…酸化物超電導積層体、１２…酸化物超電導導体。 DESCRIPTION OF SYMBOLS 1 ... Oxide superconducting conductor, 2 ... Base material, 3 ... Underlayer, 4 ... Orientation layer, 5 ... Cap layer, 6 ... Oxide superconducting layer, 7 ... Protective layer, 8 ... Stabilizing layer, 9 ... Oxide superconducting Laminated body, 10 ... insulating coating layer, 11 ... oxide superconducting laminate, 12 ... oxide superconducting conductor.
Claims (5)
前記Ａｇの保護層は、物理的蒸着法により、前記基材を２００℃〜８００℃の範囲に加熱しながら成膜されたものであり、
前記Ａｇの保護層の表面粗さＲｚが１３００ｎｍ以下であることを特徴とする酸化物超電導導体。 An oxide superconducting conductor comprising a base material, an orientation layer provided above the base material, an oxide superconducting layer, and an Ag protective layer,
The protective layer of Ag is formed by heating the base material in a range of 200 ° C. to 800 ° C. by physical vapor deposition,
The oxide superconducting conductor, wherein the surface roughness Rz of the protective layer of Ag is 1300 nm or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2011142870A JP5693398B2 (en) | 2011-06-28 | 2011-06-28 | Oxide superconducting conductor and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2011142870A JP5693398B2 (en) | 2011-06-28 | 2011-06-28 | Oxide superconducting conductor and manufacturing method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2013012321A JP2013012321A (en) | 2013-01-17 |
| JP5693398B2 true JP5693398B2 (en) | 2015-04-01 |
Family
ID=47686051
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2011142870A Active JP5693398B2 (en) | 2011-06-28 | 2011-06-28 | Oxide superconducting conductor and manufacturing method thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP5693398B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015098934A1 (en) * | 2013-12-25 | 2015-07-02 | 株式会社フジクラ | Oxide superconducting wire material and oxide superconducting wire material manufacturing method |
| JP2016149247A (en) * | 2015-02-12 | 2016-08-18 | 住友電気工業株式会社 | Method for producing oxide superconducting wire material and oxide superconducting wire material |
| DE112016007398T5 (en) | 2016-10-31 | 2019-07-25 | Sumitomo Electric Industries, Ltd. | Superconducting wire and superconducting coil |
| CN111272533A (en) * | 2020-03-07 | 2020-06-12 | 北京工业大学 | Sample preparation method for researching oxygen element diffusion mechanism of high-temperature superconducting material |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3756322B2 (en) * | 1998-06-09 | 2006-03-15 | 株式会社フジクラ | Manufacturing apparatus and manufacturing method of oxide superconducting conductor |
| JP3771107B2 (en) * | 2000-03-24 | 2006-04-26 | 株式会社フジクラ | Oxide superconducting conductor, manufacturing apparatus and manufacturing method thereof |
| JP4369669B2 (en) * | 2003-02-14 | 2009-11-25 | 新日本製鐵株式会社 | Oxide superconductor, oxide superconductor energization element, and method for producing the same |
-
2011
- 2011-06-28 JP JP2011142870A patent/JP5693398B2/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| JP2013012321A (en) | 2013-01-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6956012B2 (en) | Method of depositing an electrically conductive oxide buffer layer on a textured substrate and articles formed therefrom | |
| JP4268645B2 (en) | Rare earth tape oxide superconductor and composite substrate used therefor | |
| JP2007311234A (en) | Superconductive thin film material and its manufacturing method | |
| JP5634166B2 (en) | Oxide superconducting wire and method for producing the same | |
| JP2007115562A (en) | Tape-shaped rare-earth group oxide superconductor and its manufacturing method | |
| JP2010086796A (en) | Polycrystalline thin film and method of manufacturing the same, and oxide superconductor | |
| JP5693398B2 (en) | Oxide superconducting conductor and manufacturing method thereof | |
| US7432229B2 (en) | Superconductors on iridium substrates and buffer layers | |
| JP5624839B2 (en) | Base material for oxide superconducting conductor and method for producing the same, oxide superconducting conductor and method for producing the same | |
| JP2013134856A (en) | Oxide superconducting wire material and method for manufacturing the same | |
| JP2012022882A (en) | Base material for oxide superconducting conductor and method of manufacturing the same, and oxide superconducting conductor and method of manufacturing the same | |
| JP5597511B2 (en) | Oxide superconducting wire and method for producing the same | |
| JP5939995B2 (en) | Superconducting wire and method of manufacturing superconducting wire | |
| JP5950826B2 (en) | Superconducting wire and method of manufacturing superconducting wire | |
| JP2013008556A (en) | Superconductive wire material | |
| JP2012212571A (en) | Oxide superconductor | |
| Shi et al. | YBCO coated conductor using biaxially textured clad composite Ni–Mn/Ni–Cr substrate | |
| JP2012150914A (en) | High-resistance material composite oxide superconducting wire material | |
| JP5730541B2 (en) | Method for manufacturing substrate for superconducting wire, and method for manufacturing superconducting wire | |
| JP5663244B2 (en) | Method for producing enamel-coated superconducting wire | |
| JP5597516B2 (en) | Superconducting wire manufacturing method | |
| JP5764421B2 (en) | Oxide superconducting conductor | |
| JP2011249162A (en) | Method for manufacturing superconducting wire rod | |
| WO2012060425A1 (en) | Base material for superconductor wire material, superconductor wire material, and method for producing superconductor wire material | |
| US20080146452A1 (en) | (113) [121] Textured Ag substrate and Tl-1223 high temperature superconducting coated conductor using the same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20131213 |
|
| A871 | Explanation of circumstances concerning accelerated examination |
Free format text: JAPANESE INTERMEDIATE CODE: A871 Effective date: 20140902 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20141029 |
|
| A975 | Report on accelerated examination |
Free format text: JAPANESE INTERMEDIATE CODE: A971005 Effective date: 20141029 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20141111 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20141226 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20150127 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20150203 |
|
| R151 | Written notification of patent or utility model registration |
Ref document number: 5693398 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R151 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |