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YBa2Cu3Oy (YBCO) foam samples show an open, porous foam structure, which may have benefits for many applications of high-Tc superconductors. As the basic material of these foams is a pseudo-single crystalline material with the directional growth initiated by a seed crystal similar to standard melt-textured samples, the texture of YBCO is a very important parameter. Therefore, we analysed the local texture and grain orientation of the individual struts forming the foam by means of atomic force microscopy (AFM) and electron backscatter diffraction (EBSD). Due to the processing route starting with Y2BaCuO5 (211), a two-phase analysis must be performed, so a high surface quality is necessary to enable an automated EBSD scan. Good quality Kikuchi patterns were obtained from both the YBCO and 211 phases. We found an inhomogeneous distribution of the residual 211 particles, which are mainly randomly oriented and have sizes ranging between 200 nm and 15 µm. In contrast to this, the YBCO matrix shows a dominating orientation with cracks with a typical distance of 1–10 µm. Furthermore, the analysis of strut cross-sections reveals that the entire strut is converted to the YBCO phase.


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Analysis of the microstructure of superconducting YBCO foams by means of AFM and EBSD

Show Author's information Michael Rudolf KOBLISCHKAa( )Anjela KOBLISCHKA-VENEVAaE. S. REDDYb,cGregor J. SCHMITZc
Institute of Experimental Physics, Saarland University, P. O. Box 151150, D-66041 Saarbrücken, Germany
ACCESS, Intzestrasse 5, 52072 Aachen, Germany
Nanonouvelle Pty Ltd., Marcoola QLD 4564, Australia

Abstract

YBa2Cu3Oy (YBCO) foam samples show an open, porous foam structure, which may have benefits for many applications of high-Tc superconductors. As the basic material of these foams is a pseudo-single crystalline material with the directional growth initiated by a seed crystal similar to standard melt-textured samples, the texture of YBCO is a very important parameter. Therefore, we analysed the local texture and grain orientation of the individual struts forming the foam by means of atomic force microscopy (AFM) and electron backscatter diffraction (EBSD). Due to the processing route starting with Y2BaCuO5 (211), a two-phase analysis must be performed, so a high surface quality is necessary to enable an automated EBSD scan. Good quality Kikuchi patterns were obtained from both the YBCO and 211 phases. We found an inhomogeneous distribution of the residual 211 particles, which are mainly randomly oriented and have sizes ranging between 200 nm and 15 µm. In contrast to this, the YBCO matrix shows a dominating orientation with cracks with a typical distance of 1–10 µm. Furthermore, the analysis of strut cross-sections reveals that the entire strut is converted to the YBCO phase.

Keywords:

high-Tc superconductors, foam, microstructure, atomic force microscopy (AFM), electron backscatter diffraction (EBSD), orientation
Received: 12 June 2014 Accepted: 23 July 2014 Published: 30 November 2014 Issue date: December 2014
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Publication history
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Publication history

Received: 12 June 2014
Accepted: 23 July 2014
Published: 30 November 2014
Issue date: December 2014

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© The author(s) 2014

Acknowledgements

We acknowledge collaborations within the European Forum for Processors of Bulk Superconductors (EFFORT), which is funded by the Engineering and Physical Sciences Research Council (EPSRC) of the UK government. We thank M. Winter (Saarland University) for his efforts with the AFM measurements. The 3D-images were prepared using the image processing software described in Ref. [30].

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