Regensburg 2000 – scientific programme
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TT: Tiefe Temperaturen
TT 24: Massive HTSL, YBCO/BSCCO Bandleiter
TT 24.1: Invited Talk
Friday, March 31, 2000, 09:30–10:00, H20
Microstructure and critical current densities of high-temperature superconducting materials for technological applications — •Oliver Eibl — Universität Tübingen, Auf der Morgenstelle 10; 72076 Tübingen
High-Tc superconducting compounds are considered for applications in the magnet and energy technology. Superconducting materiales relevant for technological applications should have critical current densities of 105 − 106 A/cm2. In YBaCuO extended crystal defects, particularly grain boundaries, limit the critical current density and, thus, the technological applications of polycrystalline material.
Among the high-Tc superconducting materials (Bi,Pb)2Sr2Ca2Cu3O10 is the most complicated but also the one with the largest potential for high-Tc superconducting components and devices. In the past efforts were undertaken to understand the modulated crystal structure and the extended crystal defects present in this material, i.e. intergrowth, disorder in the individual sublattices etc.. High-resolution TEM combined with image simulation was used to image and analyse the structure of the defects. The large anisotropy of the crystal structure requires highly textured material with the current flowing parallel to the crystallographic (001) plane. In silver sheathed (Bi,Pb)2223 tapes the mechanisms limiting the critical current densities, i.e. the anisotropy and the granular microstructure, are discussed.
Besides the crystal defects the phase formation of this highly anisotropic compound is of great interest. New quantitative methods for the characterisation of the microstructure, i.e. chemical imaging, and results obtained with these methods are presented.