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Advances in Materials Science and Engineering
Volume 2013, Article ID 578434, 7 pages
http://dx.doi.org/10.1155/2013/578434
Research Article

SmBa2NbO6 Nanopowders, an Effective Percolation Network Medium for YBCO Superconductors

1Electronic Materials Research Laboratory, Department of Physics, Mar Ivanios College, Thiruvananthapuram, Kerala 695015, India
2Dielectric Materials Research Laboratory, Department of Physics, St. John’s College, Kollam District, Anchal, Kerala 691306, India

Received 30 May 2013; Accepted 29 August 2013

Academic Editor: John W. Gillespie

Copyright © 2013 S. Vidya et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The percolation behavior of superconductor-insulator composite, YBa2Cu3O7–δ, and nano SmBa2NbO2 synthesized by modified combustion technique was studied. Particle size of nano SmBa2NBO6 was determined using transmission electron microscopy. The chemical nonreactivity of nano SmBa2NbO6 with YBCO is evident from the X-Ray diffraction study which makes it a suitable nanoceramic substrate material for high temperature superconducting films. A systematic increase in the sintered density, approaching the optimum value of the insulating nanophase is clearly observed, as the vol.% of YBCO in the composite decreases. SEM micrograph showed uniform distribution of nanopowder among the large clusters of YBCO. The obtained percolation threshold is ~26 vol% of YBCO in the composite. All the composites below the threshold value showed  K even though the room resistivity increases with increase in vol.% of nano SmBa2NbO6. The values of critical exponents obtained matches well with the theoretically expected ones for an ideal superconductor-insulator system.