JP2004010390A - METHOD FOR SYNTHESIZING SUPERCONDUCTING BORIDE MgB2 FROM MELT BY ELECTRODEPOSITION - Google Patents
METHOD FOR SYNTHESIZING SUPERCONDUCTING BORIDE MgB2 FROM MELT BY ELECTRODEPOSITION Download PDFInfo
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- JP2004010390A JP2004010390A JP2002163764A JP2002163764A JP2004010390A JP 2004010390 A JP2004010390 A JP 2004010390A JP 2002163764 A JP2002163764 A JP 2002163764A JP 2002163764 A JP2002163764 A JP 2002163764A JP 2004010390 A JP2004010390 A JP 2004010390A
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、超伝導ホウ化物ＭｇＢ２（Ｔｃ＝３９Ｋ）超伝導薄膜、及び超伝導線材の作製方法に関するものである。
【０００２】
【従来の技術】
超伝導薄膜は超伝導量子干渉素子（ＳＱＵＩＤ）として高感度な磁束計に用いられる。又、超伝導線材は超伝導電磁磁石として強磁場の発生に使われる。両者とも医療におけるＣＴスキャン装置の他、学術研究等で広く利用されている。
【０００３】
【発明が解決しようとする課題】
先頃、金属間化合物として最高のＴｃ＝３９Ｋを示すホウ化物ＭｇＢ２が発見され、従来のＡ１５型金属間化合物（ＴＣ＝１５Ｋ程度）に代わるものとしてその応用が期待されている。
【０００４】
ＭｇＢ２は、しかし、構成元素ＭｇとＢの極端な蒸気圧の違いから、単相バルク試料の合成すら難しいのが現状である。超伝導体の実用に不可欠な線材作製技法、又は素子化に必要な薄膜作製技術は、現在まで得られていない。
【０００５】
【課題を解決するための手段】
本発明は、簡単な装置構成により、ＭｇＢ２を融液中から電気析出法（電析法）により薄膜状に合成する手法を提供するものである。この手法を最適化することにより、どのような形状の基板金属に対してもＭｇＢ２を一様な厚みで育成できる。
【０００６】
即ち、本発明は、マグネシウムハロゲン化物と塩化カリウムの混合物にマグネシウムのホウ酸塩を加えて得られた粉体混合物を耐熱性ボートに充填し、この混合物中に負電極及び正電極を挿入し、これらを加熱炉中で不活性ガス雰囲気下で加熱してボート中の混合物を熔融して融液とした後、両電極間に直流電流を印加し、負電極上にＭｇＢ２を析出させることからなる超伝導ホウ化物ＭｇＢ２の融液からの電析法による合成方法である。
【０００７】
したがって、予め線状に成形した金属線上にＭｇＢ２をメッキすることにより、ＭｇＢ２の線材を作製することができる。又、平面基板上への育成も可能である。即ち、ＭｇＢ２を利用したジョセフソン素子等、薄膜構成を必要とする系の作製に対しても有力である。
【０００８】
【発明の実施の形態】
本発明は、新物質合成実験の途上、いくつかの合成方法を試みるなかで、電解法／電析法による難合成物質の合成法として開発されたものである。ＭｇＢ２は、非常に蒸気圧の高いＭｇと逆に非常に融点の高いホウ素の化合物であるが、そこで行われた一連の高蒸気圧物質合成の試行過程において、本発明は、電気析出法を使用してＭｇＢ２を合成する方法を見いだした。
【０００９】
又、本発明は、現在盛んに用いられている真空蒸着等の高度且つ高価な装置を用いた製膜法と違い、メッキ用の僅かな装置だけで簡単にＭｇＢ２の膜を作製することを可能にする。それだけでなく、真空蒸着では不可能な基板面への製膜も可能である。これは、例えば、初めからコイル状に成形した金属線にメッキを施すことにより、ＭｇＢ２超伝導体マグネットを作製することができることを意味している。
【００１０】
更に又、本発明においては、実施例に示されるように、ＭｇＣｌ２／Ｍｇ（ＢＦ４）２６Ｈ２Ｏ／ＭｇＢ２Ｏ４を混合系を用いることにおいて、ＭｇＢ２の合成が可能であった。融体の融点を下げる目的で、アルカリ金属ホウ酸塩の添加が有効である。電極材料としては、実施例ではＰｔ／Ａｕを使用したが、他の金属／導電性物質も使用可能である。
【００１１】
【実施例】
市販の試薬ＭｇＣｌ２、Ｍｇ（ＢＦ４）２６Ｈ２Ｏ、及びＭｇＢ２Ｏ４を重量比１０：１：１にて総量２．５ｇ秤量する（以下粉末試料と呼ぶ）。アルミナボートの一端に直径１ｍｍの白金線をボート底に這わせるように固定する。同様に、ボートの反対の端に同径の金を固定する。白金線及び金線それぞれに直径０．３ｍｍの金線（以下リード線と呼ぶ）を圧着する。
【００１２】
粉末試料をボートに満たした後、これを石英炉心管を備えた横型電気炉に入れる。炉心管の一端をふさぐゴム栓にチューブを取り付け、アルゴンガスラインにつなぐ。炉心管の他端のゴム栓には排気用のチューブに加え、二つ穴のガイシを挿入する。ガイシを介してリード線を炉心管外部に導き、直流電源に接続する。リード線が互いに触れないよう注意を払う。白金線を負極、金線を正極に結合する。
【００１３】
アルゴンガスを１リットル毎分程度流しながら炉温度を６００℃まで上げる。粉末試料は融体となる。リード線に４Ｖ直流電圧を印加、数百ミリアンペアの通電を確認したらそのまま数時間静置する。数時間後、炉温度を常温に戻し、ボートを取出す。フラックスを除くため、蒸留水にボートを浸ける。フラックス除去後、黒色物質（ＭｇＢ２）に被覆された白金線を得た。
【００１４】
白金線上に育成されたＭｇＢ２の磁化率・温度曲線を示すと図１のとおりである。測定磁場は２０ガウスで、無磁場中冷却（ＺＦＣ）、磁場中冷却（ＦＣ）それぞれの曲線を示している。磁気的特性として、３７Ｋにおいて磁化率曲線に特異点がみられるが、これがＭｇＢ２の超電導転換に対応している。
【００１５】
【発明の効果】
従来の真空蒸着装置を用いた大がかりな製膜処理に比べて、本発明の簡単な機構の装置を使用することにより、合成困難なＭｇＢ２の薄膜、線材の作製が極めて低コストで可能となる。
【００１６】
即ち、本発明により、現在盛んに用いられている真空蒸着等の高度且つ高価な装置を用いた製膜法と違い、メッキ用の僅かな装置だけで簡単にＭｇＢ２の膜を作成することを可能にする。それだけでなく、真空蒸着では不可能な基板面への製膜も可能である。これは、例えば、初めからコイル状に成形した金線にメッキを施すことにより、ＭｇＢ２超伝導マグネットを作製することができることを意味している。
【００１７】
又、ＭｇＢ２薄膜は超伝導量子干渉素子（ＳＱＵＩＤ）として高感度な磁束計に用いられる。その超伝導線材は超伝導電磁磁石として強磁場の発生に使用される。両者とも医療におけるＣＴスキャン装置の他、学術研究等で利用される。
【図面の簡単な説明】
【図１】白金線上に育成されたＭｇＢ２の磁化率・温度曲線を示すと図１のとおりである。
【図２】本発明の方法でＭｇＢ２を作製する装置の図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a superconducting boride MgB 2 (Tc = 39K) superconducting thin film and a method for producing a superconducting wire.
[0002]
[Prior art]
The superconducting thin film is used for a highly sensitive magnetometer as a superconducting quantum interference device (SQUID). The superconducting wire is used as a superconducting electromagnetic magnet to generate a strong magnetic field. Both are widely used in academic research and the like in addition to CT scanning devices in medical treatment.
[0003]
[Problems to be solved by the invention]
Recently, a boride MgB 2 showing the highest Tc = 39K as an intermetallic compound was discovered, and its application is expected as a substitute for the conventional A15 type intermetallic compound (TC = about 15K).
[0004]
At present, however, it is difficult to synthesize a single-phase bulk sample of MgB 2 because of the extreme difference in vapor pressure between the constituent elements Mg and B. Until now, a technique for producing a wire material essential for practical use of a superconductor, or a technique for producing a thin film necessary for realizing an element has not been obtained.
[0005]
[Means for Solving the Problems]
The present invention provides a method of synthesizing MgB 2 into a thin film from a melt by an electrodeposition method (electrodeposition method) with a simple apparatus configuration. By optimizing this method, MgB 2 can be grown with a uniform thickness for any shape of substrate metal.
[0006]
That is, the present invention fills a heat-resistant boat with a powder mixture obtained by adding magnesium borate to a mixture of magnesium halide and potassium chloride, inserting a negative electrode and a positive electrode into this mixture, These are heated in a heating furnace under an inert gas atmosphere to melt the mixture in the boat into a melt, and then a direct current is applied between both electrodes to precipitate MgB 2 on the negative electrode. This is a method of synthesizing a superconducting boride MgB 2 from a melt by an electrodeposition method.
[0007]
Therefore, a MgB 2 wire can be manufactured by plating MgB 2 on a metal wire that has been previously formed into a linear shape. It is also possible to grow on a flat substrate. That is, the present invention is also effective in producing a system requiring a thin film structure, such as a Josephson device using MgB 2 .
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention has been developed as a method for synthesizing difficult-to-synthesize substances by an electrolytic method / electrodeposition method while trying several synthetic methods in the course of a new substance synthesis experiment. MgB 2 is a compound of boron having a very high melting point, contrary to Mg having a very high vapor pressure. I found a method for synthesizing MgB 2 using.
[0009]
Further, the present invention is different from a film forming method using an advanced and expensive apparatus such as vacuum evaporation which is currently used widely, and is intended to easily produce a MgB 2 film with only a small apparatus for plating. enable. In addition, it is possible to form a film on a substrate surface that cannot be obtained by vacuum deposition. This means that, for example, an MgB 2 superconductor magnet can be manufactured by plating a metal wire formed into a coil shape from the beginning.
[0010]
Furthermore, in the present invention, as shown in the examples, the MgCl 2 / Mg (BF 4) 2 6H 2 O / MgB 2 O 4 in the use of the mixed system, it was possible synthesis of MgB 2 is . In order to lower the melting point of the melt, it is effective to add an alkali metal borate. As the electrode material, Pt / Au is used in the embodiment, but other metals / conductive substances can be used.
[0011]
【Example】
Commercially available reagents MgCl 2, Mg (BF 4) 2 6H 2 O, and MgB 2 O 4 in a weight ratio of 10: 1: (hereinafter referred to as powder sample) at 1 total 2.5g weighed. A platinum wire having a diameter of 1 mm is fixed to one end of the alumina boat so as to crawl on the bottom of the boat. Similarly, secure gold of the same diameter to the opposite end of the boat. A 0.3 mm diameter gold wire (hereinafter referred to as a lead wire) is crimped to each of the platinum wire and the gold wire.
[0012]
After the powder sample is filled in the boat, it is placed in a horizontal electric furnace equipped with a quartz furnace tube. Attach the tube to a rubber stopper covering one end of the furnace tube, and connect to the argon gas line. In addition to the exhaust tube, a two-hole insulator is inserted into the rubber stopper at the other end of the furnace tube. The lead wire is led out of the furnace tube through the insulator and connected to a DC power supply. Take care that the leads do not touch each other. The platinum wire is connected to the negative electrode and the gold wire is connected to the positive electrode.
[0013]
The furnace temperature is raised to 600 ° C. while flowing argon gas at about 1 liter per minute. The powder sample becomes a melt. Apply a 4V DC voltage to the lead wire, and after confirming that a current of several hundred milliamperes has been supplied, leave it for several hours. After several hours, the furnace temperature is returned to room temperature and the boat is removed. Soak the boat in distilled water to remove the flux. After removing the flux, a platinum wire coated with a black substance (MgB 2 ) was obtained.
[0014]
FIG. 1 shows a magnetic susceptibility / temperature curve of MgB 2 grown on a platinum wire. The measured magnetic field is 20 gauss, and the curves for cooling under no magnetic field (ZFC) and cooling under magnetic field (FC) are shown. As a magnetic property, a singular point is observed in the susceptibility curve at 37K, which corresponds to the superconducting conversion of MgB 2 .
[0015]
【The invention's effect】
Compared to a large-scale film forming process using a conventional vacuum deposition apparatus, by using the apparatus having the simple mechanism of the present invention, it is possible to produce a MgB 2 thin film and a wire that are difficult to synthesize at an extremely low cost. .
[0016]
That is, according to the present invention, unlike a film forming method using an advanced and expensive apparatus such as vacuum evaporation which is currently used widely, it is possible to easily form a MgB 2 film with only a small apparatus for plating. enable. In addition, it is possible to form a film on a substrate surface that cannot be obtained by vacuum deposition. This means that, for example, a MgB 2 superconducting magnet can be manufactured by plating a gold wire formed into a coil shape from the beginning.
[0017]
The MgB 2 thin film is used as a superconducting quantum interference device (SQUID) in a highly sensitive magnetometer. The superconducting wire is used as a superconducting electromagnetic magnet to generate a strong magnetic field. Both of them are used in medical research, as well as in academic research and the like.
[Brief description of the drawings]
FIG. 1 shows the magnetic susceptibility / temperature curve of MgB 2 grown on a platinum wire as shown in FIG.
FIG. 2 is a diagram of an apparatus for producing MgB 2 by the method of the present invention.
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002163764A JP4120955B2 (en) | 2002-06-05 | 2002-06-05 | Synthesis Method of Superconducting Boride MgB2 by Electrodeposition from Melt |
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|---|---|---|---|
| JP2002163764A JP4120955B2 (en) | 2002-06-05 | 2002-06-05 | Synthesis Method of Superconducting Boride MgB2 by Electrodeposition from Melt |
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| Publication Number | Publication Date |
|---|---|
| JP2004010390A true JP2004010390A (en) | 2004-01-15 |
| JP4120955B2 JP4120955B2 (en) | 2008-07-16 |
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| JP2002163764A Expired - Fee Related JP4120955B2 (en) | 2002-06-05 | 2002-06-05 | Synthesis Method of Superconducting Boride MgB2 by Electrodeposition from Melt |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004010389A (en) * | 2002-06-05 | 2004-01-15 | Japan Atom Energy Res Inst | MELT ELECTRODEPOSITION SYNTHESIS METHOD FOR SUPERCONDUCTING BORIDE MgB2 |
| JP2007141793A (en) * | 2005-11-22 | 2007-06-07 | National Institute For Materials Science | Manufacturing method by electroplating of superconductive mgb2 film |
| CN101864587A (en) * | 2009-04-20 | 2010-10-20 | 鸿富锦精密工业（深圳）有限公司 | Device and method for forming nanoscale metal particles/metal composite coatings |
| CN102242371A (en) * | 2011-06-24 | 2011-11-16 | 武汉大学 | Preparation method and application of superfine calcium hexaboride |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002321911A (en) * | 2001-04-26 | 2002-11-08 | National Institute For Materials Science | METHOD FOR MANUFACTURING MgB2 SUPERCONDUCTOR |
| JP2003238144A (en) * | 2002-02-21 | 2003-08-27 | Japan Atom Energy Res Inst | METHOD FOR ELECTROCHEMICALLY SYNTHESIZING SUPERCONDUCTING BORON COMPOUND MgB2 |
-
2002
- 2002-06-05 JP JP2002163764A patent/JP4120955B2/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002321911A (en) * | 2001-04-26 | 2002-11-08 | National Institute For Materials Science | METHOD FOR MANUFACTURING MgB2 SUPERCONDUCTOR |
| JP2003238144A (en) * | 2002-02-21 | 2003-08-27 | Japan Atom Energy Res Inst | METHOD FOR ELECTROCHEMICALLY SYNTHESIZING SUPERCONDUCTING BORON COMPOUND MgB2 |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004010389A (en) * | 2002-06-05 | 2004-01-15 | Japan Atom Energy Res Inst | MELT ELECTRODEPOSITION SYNTHESIS METHOD FOR SUPERCONDUCTING BORIDE MgB2 |
| JP2007141793A (en) * | 2005-11-22 | 2007-06-07 | National Institute For Materials Science | Manufacturing method by electroplating of superconductive mgb2 film |
| CN101864587A (en) * | 2009-04-20 | 2010-10-20 | 鸿富锦精密工业（深圳）有限公司 | Device and method for forming nanoscale metal particles/metal composite coatings |
| CN102242371A (en) * | 2011-06-24 | 2011-11-16 | 武汉大学 | Preparation method and application of superfine calcium hexaboride |
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| Publication number | Publication date |
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| JP4120955B2 (en) | 2008-07-16 |
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