期刊
NPG ASIA MATERIALS
卷 4, 期 -, 页码 -出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/am.2012.3
关键词
carbon role; densification; 3D tomogram; MgB2; TEM
资金
- Australian Research Council [DP0770205]
- Hyper Tech Research Inc., OH, USA
- Japan Society for the Promotion of Science (JSPS)
- Ministry of Education, Science and Technology (MEST), Japan
- MEST, Japan [2010-0029136]
Increasing dissipation-free supercurrent has been the primary issue for practical application of superconducting wires. For magnesium diboride, MgB2, 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. NPG Asia Materials (2012) 4, e3; doi:10.1038/am.2012.3; published online 18 January 2012
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