Substitution of Cu by Fe in the superconducting ceramic oxide EuBa2Cu3Oy: Structure, electrical conductivity, and microwave response |
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Authors: | T E Phillips J Bohandy and K Moorjani |
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Affiliation: | (1) Milton S. Eisenhower Research Center, The Johns Hopkins University Applied Physics Laboratory, 20707 Laurel, Maryland |
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Abstract: | A series of EuBa2(Cu1–x
Fe
x
)3Oy (0.0x0.15) ceramics were prepared and examined by thermogravimetric analysis, X-ray powder diffraction, electrical resistance measurements, and a magnetically modulated microwave absorption technique. The oxygen content (y=6.98±0.03), determined by thermogravimetric analysis in a reducing atmosphere, was independent of the iron concentration forx0.12. The introduction of iron into the EuBa2Cu3O
y
lattice, via substitution into copper sites, effects a progressive decrease in the superconducting transition temperature with increasing iron concentration. Normal-state conductivity similarly progresses from a low resistivity and negative temperature coefficient behavior, to a semiconducting-like response at the high iron concentrations. X-ray powder diffraction measurements indicate that material containing 6% iron and above is tetragonal, yet it remains superconducting with up to at least 12% iron. |
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Keywords: | superconductivity EuBa2Cu3Oy iron substitution oxygen stoichiometry conductivity microwave response cell constants |
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