Direct observation of nanometer-scale amorphous layers and oxide crystallites at grain boundaries in polycrystalline Sr1−xKxFe2As2 superconductors

Abstract
We report here an atomic resolution study of the structure and composition of the grain boundaries in polycrystallineSr0.6K0.4Fe2As2superconductor. A large fraction of grain boundaries contain amorphous layers larger than the coherence length, while some others contain nanometer-scale crystallites sandwiched in between amorphous layers. We also find that there is significant oxygen enrichment at the grain boundaries. Such results explain the relatively low transport critical current density (Jc) of polycrystalline samples with respect to that of bicrystal films.

Citation
Direct observation of nanometer-scale amorphous layers and oxide crystallites at grain boundaries in polycrystalline Sr1−xKxFe2As2 superconductors 2011, 98 (22):222504 Applied Physics Letters

Publisher
AIP Publishing

Journal
Applied Physics Letters

DOI
10.1063/1.3592580

arXiv
1104.5372

Additional Links
http://scitation.aip.org/content/aip/journal/apl/98/22/10.1063/1.3592580http://arxiv.org/abs/1104.5372

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