Critical currents and flux creep in melt processed high Tc oxide superconductors
β Scribed by M. Murakami; S. Gotoh; N. Koshizuka; S. Tanaka; T. Matsushita; S. Kambe; K. Kitazawa
- Publisher
- Elsevier Science
- Year
- 1990
- Tongue
- English
- Weight
- 684 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0011-2275
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β¦ Synopsis
YBa2Cu307 crystals fabricated by a quench and melt growth process contain fine Y2BaCuO5 particles. These fine precipitates are considered to have three beneficial effects: they suppress crack formation; they promote oxygen diffusion; and they act as pinning centres. Such crystals exhibit larger flux pinning than single crystals and their magnetic behaviour can be understood in terms of the critical state model which has been developed for conventional type II superconductors. Both transport and magnetization measurements gave Jo values exceeding 30 000 A cm-2 at 77 K and 1 T. Flux creep rate is also much smaller than that of single crystals and a value of pinning energy, U, comparable to that of conventional superconductors was obtained. A theoretical estimation of the contribution of 211 precipitates to flux pinning is also presented.
π SIMILAR VOLUMES
Y1Ba2Cu307\_x and Bi2Sr2CalCu208+ x Ag sheathed high Tc superconductor wires have been prepared using the powder in tube technique. Characterization of wire specimens was performed mainly by measuring critical current densities at 77 K and 4.2 K, as well as by a.c. susceptibility measurements. Where
This paper reports the experimental investigations into two different methods of reducing flux creep and magnetic relaxation in high T c YBa2Cu307 and low T c Nb-Ti. For temperatures T \_< 4.2 K temperature reduction leads to a considerable reduction of the flux creep rate. The second method for red