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Crystal Structures and Superconductivity in the La1.5−xBa1.5+Cu7+ySystem

Published online by Cambridge University Press:  28 February 2011

JE. Greedan
Affiliation:
Institute for Materials Research, McMaster University, Hamilton, Ontario, Canada, L8S 4M1
A. H. O'Reilly
Affiliation:
Institute for Materials Research, McMaster University, Hamilton, Ontario, Canada, L8S 4M1
C. V. Stager
Affiliation:
Institute for Materials Research, McMaster University, Hamilton, Ontario, Canada, L8S 4M1
F. Razavi
Affiliation:
Physics Department, Brock University, St. Catherines, Ontario, Canada.
W. Abriel
Affiliation:
Institut fur Anorganische Chemie, Universität Hannover, 3000 Hannover 1. F.D.R.
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Abstract

Members of the solid solution system La1.5−xBa1.5+Cu7+ywith x = 0, 0.125, 0.25. 0.375 and 0.5 have been prepared both in air and under one atmosphere of flowing oxygen. In general, except for x =0, the oxygen annealed compounds are superconducting while the air-annealed samples are semiconductors. Tc's measured by Meissner effect and resistivity data range to 70K. The crystal symmetry in all cases is apparently tetragonal as verified for x = 0.375 by variable temperature Guinier x-ray experiments at temperatures down to 8K. Crystal structures have been refined from neutron powder diffraction data. A correlation is noted between Cu-0 distances which connect adjacent Cu planes - the average copper valence and the occurrence of superconductivity.

Type
Research Article
Copyright
Copyright © Materials Research Society 1988

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References

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