Superconducting properties of MgB2 tapes and wires

• Published in: Physica. C, Superconductivity Vol. 385; no. 1-2; pp. 286 - 305
• Main Authors: Flükiger, R., Suo, H.L., Musolino, N., Beneduce, C., Toulemonde, P., Lezza, P.
• Format: Journal Article
• Language: English
• Published: 01-03-2003
• ISSN: 0921-4534
• DOI: 10.1016/S0921-4534(02)02307-9

An overview of the current state of development of MgB2 wires and tapes prepared by several techniques is presented, based on the known literature data and our own results. We focus on the powder-in-tube processing method, using pre-reacted MgB2 powders surrounded by an Fe sheath (ex situ processing route). The study of the effect of the initial MgB2 particle size shows that after reducing the initial particles by ball milling to sizes of the order of 3 *mm the degree of texturing and the upper critical field, Bc2 remain unchanged, while both the critical current density, Jc, and the irreversibility field, Birr, show a considerable increase, followed by a decrease after longer milling times. After various recrystallization times and temperatures we show that a critical amount of impurities introduced during the particle reduction process is responsible for the observed maximum of Jc and Birr Our analysis indicates that this is a grain boundary effect, thus pointing