Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 8: Postersitzung I: Supraleitung
TT 8.11: Poster
Montag, 8. März 2004, 14:30–19:00, Poster A
Finite size effects and JC simulations in high-JC coated conductors — •J. Hänisch, L. Fernández, C. Cai, V.S. Sarma, L. Schultz und B. Holzapfel — IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany
The superconducting layer in coated conductors consists a network of small
angle grain boundaries. Due to the limitation of JC on grain
boundaries in high-TC superconductors, the current flow through
this network is of percolative nature and depends on misorientation angle
distribution, width and length of the tape and grain shape.
The current flow through grain boundary networks had been simulated widely
with purely statistical models on artificial networks. Recent
investigations of biaxially textured orthorhombic materials (as YBCO on
coated conductors is) showed a nonrandom distribution of misorientation
angles in this materials.
JC simulations using a fast and simple limiting-path algorithm
were used to investigate the influence of the grain boundary misorientation
statistics on JC in realistic networks. Input of the simulation
program are large EBSD (electron back scattering diffraction) maps and the
misorientation angle dependence of JC. We found a strong
dependence of JC on the bridge width for bridges smaller then 20
grains (in comparisson to purely statistical models), whereas JC
is not strongly varying for wider bridges. In rotating the whole EBSD map,
we could simulate the influence of the grain aspect ratio on JC.
In current direction elongated grains show significantly higher JC
values. Both these results are promissing for the performance of coated
conductors.