E-J properties of the high-Tc materials are related to the distribution of the local critical current density Jc. From the previous results on Bi2212 thick films and practical Ag-sheathed Bi2212 tapes, we found that the distribution of the local Jc is much affected by microstructures, and the local Jc distribution becomes broad and asymmetric for well aligned plate-like Bi2212 grains. However, from a viewpoint of microstructures, the origin of the asymmetric Jc distribution remains unclear. In order to understand the relationship between the J c distribution of Bi2212 materials and microstructure, we propose a "two directional Jc distribution model". In this model, the difference of the local Jc distributions for various kinds of Bi2212 samples was explained in terms of the two different directional current flows and the aspect ratio of the grains. Moreover, the possibility of the small n-value even for high Jc materials in Bi2212 is also shown.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering