Access Restriction

Author Polyanskii, A.A. ♦ Yamamoto, A. ♦ Iwayama, I. ♦ Shimoyama, J. ♦ Kishio, K. ♦ Larbalestier, D.C.
Sponsorship Council on Superconductivity ♦ Appl. Superconductivity Conference Inc ♦ MIT
Source IEEE Xplore Digital Library
Content type Text
Publisher Institute of Electrical and Electronics Engineers, Inc. (IEEE)
File Format PDF
Copyright Year ©2002
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Physics ♦ Electricity & electronics ♦ Technology ♦ Engineering & allied operations ♦ Applied physics
Subject Keyword Microstructure ♦ Optical imaging ♦ Manufacturing processes ♦ Optical device fabrication ♦ Critical current ♦ Magnetic properties ♦ Magnetization ♦ Hysteresis ♦ Magnetic field measurement ♦ Large-scale systems ♦ polycrystalline bulk ♦ Connectivity ♦ critical current ♦ current obstacle ♦ magnesium diboride ♦ magneto-optical
Abstract Magneto optical imaging (MOI) was performed for polycrystalline MgB<sub>2</sub> bulks manufactured by various fabrication processes to investigate the relationship between critical current properties, microstructures and current obstacles. In dense samples prepared by the diffusion method, steep field gradients corresponding to high J<sub>c</sub> were shown by MOI, even though some larger scale current obstacles such as cracks and local porous regions were found. For a crack-free, dense sample, high J<sub>c</sub> over 0.4 MA/cm<sup>2</sup> at 20 K at 150 mT was found both by MOI and magnetization hysteresis measurements. On the other hand, relatively uniform field distribution without large-scale current obstacles was observed by MOI for a porous in-situ processed sample, in spite of its much lower Jc. This suggests that uniformly dispersed current obstacles on scales finer than the MOI resolution (~ few mum) exist in porous bulks. More homogenous microstructure without such fine-scale obstructions and elimination of voids and cracks are all important for improving J<sub>c</sub> of MgB<sub>2</sub>.
Description Author affiliation :: Florida State Univ., Tallahassee
ISSN 10518223
Education Level UG and PG
Learning Resource Type Article
Publisher Date 2007-06-01
Publisher Place U.S.A.
Rights Holder Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Volume Number 17
Issue Number 2
Size (in Bytes) 1.77 MB
Page Count 4
Starting Page 2746
Ending Page 2749

Source: IEEE Xplore Digital Library