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Lian, Zhou; Pingxiang, Zhang; Keguang, Wang; Jingrong, Wang; Zehua, Du; Ping, Ji
Advances in cryogenic engineering materials. Volume 38, Part B1992
Advances in cryogenic engineering materials. Volume 38, Part B1992
AbstractAbstract
[en] Many studies of critical current density (Jc) from the point of view of application in liquid nitrogen have been made since the discovery of 90K YBa2Cu3Oy (YBCO) superconductor. It is believed that the weak links between grains are responsible for the low Jc of sintered YBCO at magnetic fields. In this work, the authors propose a new approach -- the powder melting process (PMP) -- through which high Jc YBCO conductor have been fabricated using precursor powders of 211 and Ba-Cu-O phase, instead of 123 phase, as starting materials. The current density of PMP YBCO sample has been over 71000A/cm2 at 1T, 77K without quench. The SEM and TEM study revealed the microstructural characteristics of PMP YBCO sample, well distributed fine 211 phase particles, microcracks-free, very clean grain boundaries and high density of crystal defects, which are believed to be responsible for its high Jc(B) values. Another direction to develop PMP is to reduce the melting temperature, which is essential for the fabrication of YBCO tape with metal substrate. A discussion is given of effects of processing parameters and microstructure on the technological advantages of this method. The YBCO conductors were fabricated via the continuously partial melting and unidirectional resolidification steps of the process using precursor powders of Y2BaCuO5 and Ba-Cu-O phase as starting materials. Since the process enables the liquid phase to react fully with the fine 211 particles during the peritectic, no CuO and BaCuO2 phase remained in 123 matrix. Strong flux pinning effect was introduced by the fine well-dispersive 211 particles via the very dense crystal defects induced around them. This new approach has potential for the fabrication of oxide conductor with metal substrates since its melting temperature is lower than that of other melting process by 50-70 degrees C. The authors have fabricated YBCO/Ag tape via PMP in N2 atmosphere
Original Title
YBCO (Y-Ba-Cu-O)
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Secondary Subject
Source
Fickett, F.R.; Reed, R.P. (eds.); 754 p; 1992; p. 929-933; Plenum Press; New York, NY (United States); CEC/ICMC: cryogenic engineering conference and international cryogenic materials conference; Huntsville, AL (United States); 11-14 Jun 1991; Plenum Publishing Corp., 233 Spring Street, New York, NY 10013 (United States)
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Book
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Conference
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