Evaluation of grain-boundaries and critical current properties in MgB2 superconductors

2011 Fiscal Year Final Research Report

• Project/Area Number: 22860019
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Single-year Grants
• Research Field: Physical properties of metals
• Research Institution: The University of Tokyo
• Principal Investigator: YAMAMOTO Akiyasu 東京大学, 大学院・工学系研究科, 助教 (20581995)
• Project Period (FY): 2010 – 2011
• Keywords: 超伝導材料 / ナノ材料 / 環境材料

Research Abstract

We have studied the microstructure, normal-state electrical connectivity and critical current density of ex-situ MgB_2 polycrystalline bulks prepared using systematically varied heating conditions under ambient pressure. The samples heated at high-temperatures of～900℃for a long period showed an increased packing factor, a larger intergrain contact area and a significantly improved electrical connectivity, all of which show the evidence of solid-state self-sintering of MgB_2. The sintered ex-situ MgB_2 bulks from the laboratory-made prereacted MgB_2 powder showed largely enhanced connectivity of～20%, which is the highest among pressureless ex-situ MgB_2 bulks, wires and tapes. Owing to the improved inter-grain coupling, high critical current density exceeding 0. 3 MA/cm^2 at 20 K under self-field was achieved. This study shows that moderately high-temperature, long-time processing is a simple but forcible way to extract the superior current carrying potential of high bulk density ex-situ MgB_2 through strengthening of inter-grain coupling by the self-sintering.

Research Products

• [Journal Article] Towards the realization of higherconnectivity in MgB2 conductors-in-situor sintered ex-situ? (2012)
  • Author(s): A. Yamamoto, H. Tanaka, J. Shimoyama, H. Ogino, K. Kishio, and T. Matsushita
  • Journal Title: Japanese Journal of Applied Physics Volume: 51巻 Pages: 010105 1-6
  • Peer Reviewed
• [Journal Article] Critical current properties at highmagnetic fields in polycrystalline MgB2 superconductors (2010)
  • Author(s): T. Matsushita, M. Kiuchi, E. S. Otabe, A. Yamamoto, J. Shimoyama, K. Kishio
  • Journal Title: Physica C Volume: 470巻 Pages: 1406-1410
  • Peer Reviewed
• [Journal Article] 磁場配向法によるc軸配向MgB2バルクの開発 (2010)
  • Author(s): 望月利彦, 山本明保, 荻野拓, 下山淳一, 岸尾光二, 堀井滋, 和田恭輔, 山田豊
  • Journal Title: 日本金属学会誌 Volume: 74巻 Pages: 444-452
  • Peer Reviewed
• [Presentation] 高温焼結ex-situ法によるMgB2線材の作製 (2012)
  • Author(s): 山本明保,田中裕也,下山淳一,伊藤明植,荻野拓,岸尾光二
  • Organizer: 第59回応用物理学関係連合講演会
  • Place of Presentation: 東京、日本
  • Year and Date: 2012-03-17
• [Presentation] MgB2超電導線材および単結晶・バルク材の磁束ピンニング機構とJc制限因子、低温工学・超電導学会 (2011)
  • Author(s): 山本明保
  • Organizer: 第2回材料研究会/九州・西日本支部合同研究会
  • Place of Presentation: 福岡、日本
  • Year and Date: 2011-12-26
• [Presentation] MgB4を介したMgB2バルクの作製 (2011)
  • Author(s): 伊藤明植,山本明保,田中裕也,下山淳一,荻野拓,岸尾光二
  • Organizer: 第85回2011年度秋季低温工学・超電導学会
  • Place of Presentation: 金沢、日本
  • Year and Date: 2011-11-11
• [Presentation] Ex-situ法MgB2バルクの臨界電流特性における原料MgB2粉末依存性 (2011)
  • Author(s): 田中裕也,山本明保,伊藤明植,下山淳一,荻野拓,岸尾光二
  • Organizer: 第85回2011年度秋季低温工学・超電導学会
  • Place of Presentation: 金沢、日本
  • Year and Date: 2011-11-11
• [Presentation] MgB2 Bulk Superconducting Magnet (2011)
  • Author(s): A. Yamamoto
  • Organizer: The 15th Japan-US Workshop on Advanced Superconductors
  • Place of Presentation: 大阪、日本
  • Year and Date: 2011-10-29
• [Presentation] Microstructure and critical current density of sinteredex-situ MgB2 polycrystals (2011)
  • Author(s): H. Tanaka, A. Yamamoto, J. Shimoyama, H. Ogino, K. Kishio
  • Organizer: 24 thInternational Symposium on Superconductivity
  • Place of Presentation: 東京、日本
  • Year and Date: 2011-10-24
• [Presentation] Ex-situ法MgB2多結晶体のコネクティビティ(2) (2011)
  • Author(s): 山本明保,田中裕也,下山淳一,伊藤明植,荻野拓,岸尾光二
  • Organizer: 第68回応用物理学会学術講演会
  • Place of Presentation: 山形、日本
  • Year and Date: 2011-09-01
• [Presentation] Ex-situ法MgB2多結晶体のコネクティビティ (2011)
  • Author(s): 山本明保,田中裕也,下山淳一,湯本英宏,荻野拓,岸尾光二
  • Organizer: 第58回応用物理学関係連合講演会
  • Place of Presentation: 日本
  • Year and Date: 2011-03-09
• [Presentation] HPCVD法により作製したチルトMgB2薄膜の輸送臨界電流特性 (2010)
  • Author(s): 山本明保, Marina Putti, Anatolii Polyanskii, Fumitake Kametani, Dmytro Abraimov, Alexander Gurevich, David Larbalestier, Chenggang Zhuang, XiaoxingXi,下山淳一,岸尾光二
  • Organizer: 第83回2010年度秋季低温工学・超電導学会
  • Place of Presentation: 鹿児島、日本
  • Year and Date: 2010-12-01
• [Presentation] Development of MgB2 Bulk Superconducting Magnet (2010)
  • Author(s): A. Yamamoto, H. Yumoto, J. Shimoyama, K. Kishio, A. Ishihara, M. Tomita
  • Organizer: 23th International Symposium on Superconductivity
  • Place of Presentation: つくば、日本
  • Year and Date: 2010-11-03
• [Presentation] Novel c-axisoriented ex-situ MgB2 conductors (2010)
  • Author(s): A. Yamamoto, T. Mochizuki, H. Tanaka, H. Ogino, J. Shimoyama, K. Kishio, S. Horii, K. Wada, Y. Yamada, Y. Shimada, S. Hata, K. Ikeda, H. Nakashima
  • Organizer: Applied Superconductivity Conference 2010
  • Place of Presentation: ワシントンDC、米国
  • Year and Date: 2010-08-05
• [Presentation] Understanding the multi-band effects oncurrent transport in tilted MgB2 films (2010)
  • Author(s): A. Yamamoto, M. Putti, A. Polyanskii, F. Kametani, D. Abraimov, A. Gurevich, D. Larbalestier, C. Zhuang, X. Xi
  • Organizer: Applied Superconductivity Conference 2010
  • Place of Presentation: ワシントンDC、米国
  • Year and Date: 2010-08-02
• [Book] chemical doping andcritical current properties- (2010)
  • Author(s): A. Yamamoto, J. Shimoyama, K. Kishio
  • Total Pages: 33
  • Publisher: Nova Science Publishers、Advances inCondensed Matter and Materials Research, Volume 6, Chapter 4. Development inmaterials processing of MgB2-microstructure
• [Patent(Industrial Property Rights)] MgB2超電導バルク磁石の製造方法、およびMgB2超電導バルク磁石 (2010)
  • Inventor(s): 山本明保、富田優、岸尾光二、石原篤、下山淳一
  • Industrial Property Number: 特願、2010-244166
  • Filing Date: 2010-10-29