Microstructural and crystallographic imperfections of MgB{sub 2} superconducting wire and their correlation with the critical current density

• Published in: AIP advances 2014-01, Vol.4 (1)
• Main Authors: Shahabuddin, Mohammed, Alzayed, Nasser S., Oh, Sangjun, Choi, Seyong, Maeda, Minoru, Hata, Satoshi, Shimada, Yusuke, Hossain, Md Shahriar Al, Kim, Jung Ho, Institute for Superconducting and Electronic Materials, University of Wollongong, North Wollongong, New South Wales 2500
• Format: Article
• Language: English
• Subjects: CRITICAL CURRENT; CRITICAL FIELD; CRYSTALLOGRAPHY; GRAIN BOUNDARIES; GRAIN SIZE; IMPURITIES; MAGNESIUM BORIDES; MATERIALS SCIENCE; POROSITY; SCATTERING; SINTERING; SUPERCONDUCTING WIRES; X RADIATION
• ISSN: 2158-3226; 2158-3226
• DOI: 10.1063/1.4862670

A comprehensive study of the effects of structural imperfections in MgB{sub 2} superconducting wire has been conducted. As the sintering temperature becomes lower, the structural imperfections of the MgB{sub 2} material are increased, as reflected by detailed X-ray refinement and the normal state resistivity. The crystalline imperfections, caused by lattice disorder, directly affect the impurity scattering between the π and σ bands of MgB{sub 2}, resulting in a larger upper critical field. In addition, low sintering temperature keeps the grain size small, which leads to a strong enhancement of pinning, and thereby, enhanced critical current density. Owing to both the impurity scattering and the grain boundary pinning, the critical current density, irreversibility field, and upper critical field are enhanced. Residual voids or porosities obviously remain in the MgB{sub 2}, however, even at low sintering temperature, and thus block current transport paths.