TY - JOUR
T1 - Microscopic role of carbon on MgB2 wire for critical current density comparable to NbTi
AU - Kim, Jung Ho
AU - Oh, Sangjun
AU - Heo, Yoon Uk
AU - Hata, Satoshi
AU - Kumakura, Hiroaki
AU - Matsumoto, Akiyoshi
AU - Mitsuhara, Masatoshi
AU - Choi, Seyong
AU - Shimada, Yusuke
AU - Maeda, Minoru
AU - MacManus-Driscoll, Judith L.
AU - Dou, Shi Xue
N1 - Funding Information:
This work was supported by the Australian Research Council (DP0770205) and Hyper Tech Research Inc., OH, USA. This study was also supported by the Japan Society for the Promotion of Science (JSPS) under the Grant-in-Aid program for JSPS fellows and the Nanotechnology Network Project of the Ministry of Education, Science and Technology (MEST), Japan. The work done at the National Fusion Research Institute was supported by the Mid-career Researcher Program through a National Research Fellowship grant funded by MEST, Japan (no. 2010-0029136). The synchrotron radiation (SR) experiments were performed at the SPring-8 facility with the approval of the Japan Synchrotron Radiation Research Institute(proposal nos. 2008B1557 and 2009A1334). We acknowledge Dr K Ikeda, Professor H Nakashima (Kyushu University, Japan), Dr J Gelb and W Yun (Xradia, Inc., USA) for their support on the XCT measurements. We also thank Dr T Kiyoshi and Dr K Itoh at the National Institute for Materials Science, Japan. We are grateful to Professor K Takase (Nihon University, Japan) and Professor Y Kuroiwa (Hiroshima University, Japan) for their valuable help on the SR experiments at SPring-8; and Dr M Eisterer (Vienna University of Technology, Austria), Professor M Sumption (The Ohio State University, USA) and Professor XX Xi (Temple University, USA) for their helpful discussions.
PY - 2012/1/18
Y1 - 2012/1/18
N2 - Increasing dissipation-free supercurrent has been the primary issue for practical application of superconducting wires. For magnesium diboride, MgB 2, carbon is known to be the most effective dopant to enhance high-field properties. However, the critical role of carbon remains elusive, and also low-field critical current density has not been improved. Here, we have undertaken malic acid doping of MgB2 and find that the microscopic origin for the enhancement of high-field properties is due to boron vacancies and associated stacking faults, as observed by high-resolution transmission electron microscopy and electron energy loss spectroscopy. The carbon from the malic acid almost uniformly encapsulates boron, preventing boron agglomeration and reducing porosity, as observed by three-dimensional X-ray tomography. The critical current density either exceeds or matches that of niobium titanium at 4.2 K. Our findings provide atomic-level insights, which could pave the way to further enhancement of the critical current density of MgB2 up to the theoretical limit.
AB - Increasing dissipation-free supercurrent has been the primary issue for practical application of superconducting wires. For magnesium diboride, MgB 2, carbon is known to be the most effective dopant to enhance high-field properties. However, the critical role of carbon remains elusive, and also low-field critical current density has not been improved. Here, we have undertaken malic acid doping of MgB2 and find that the microscopic origin for the enhancement of high-field properties is due to boron vacancies and associated stacking faults, as observed by high-resolution transmission electron microscopy and electron energy loss spectroscopy. The carbon from the malic acid almost uniformly encapsulates boron, preventing boron agglomeration and reducing porosity, as observed by three-dimensional X-ray tomography. The critical current density either exceeds or matches that of niobium titanium at 4.2 K. Our findings provide atomic-level insights, which could pave the way to further enhancement of the critical current density of MgB2 up to the theoretical limit.
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U2 - 10.1038/am.2012.3
DO - 10.1038/am.2012.3
M3 - Article
AN - SCOPUS:84859297180
SN - 1884-4049
VL - 4
JO - NPG Asia Materials
JF - NPG Asia Materials
IS - 1
M1 - e3
ER -