Individual grain boundary properties and overall performance of metal-organic-deposition coated conductors

TL;DR

This study investigates how individual grain boundaries in metal-organic-deposition coated conductors influence overall current capacity, revealing that boundary meandering significantly limits performance even at high magnetic fields.

Contribution

It provides new insights into the role of grain boundary meandering in limiting critical current density in coated conductors, linking single boundary behavior to polycrystalline track performance.

Findings

Grain boundaries limit Jc even at high fields in the force-free orientation.

Narrower tracks exhibit flatter Jc dependence, indicating reduced boundary effects.

Grain boundary meandering is a key factor affecting conductor performance.

Abstract

We have investigated single grain boundaries (GBs) isolated in coated conductors produced by Metal-Organic Deposition (MOD). When a magnetic field is swept in the film plane, an angle-dependent crossover from boundary to grain limited critical current density Jc is found. In the force-free orientation, even at fields as high as 8 T, the GBs still limit Jc. We deduce that this effect is a direct consequence of GB meandering. We have employed these single GB results to explain the dependence of Jc of polycrystalline tracks on their width: in-plane measurements become flatter as the tracks are narrowed down. This result is consistent with the stronger GB limitation at field configurations close to force-free found from the isolated boundaries. Our study shows that for certain geometries even at high fields the effect of GBs cannot be neglected.