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Superconducting properties of sodium doped (Pb,Cd)-1212 type compounds
Published in Elsevier
2000
Volume: 339
   
Issue: 2
Pages: 137 - 142
Abstract
The effect of sodium doping (3-8 mol%) on the structural, thermal and superconducting properties of (Pb0.5, Cd0.5)Sr2(Y0.6,Ca0.4)Cu2O7-δ has been studied. For 5 mol% NaNO3 doping, relatively pure superconducting phase was formed without SrCuO2 and Sr5Pb3CuO12 impurities as observed in both 3% and 8% doped as well as undoped superconductors. The cell parameters and cell volumes are also found to be minimum for the 5% doped superconductor, but were slightly larger than for the undoped superconductor. Highest Tc of 55 K was also observed for 5% doped sodium containing sample and the Tc enhancement was 15 K above the sodium free superconductor. The effect of calcium content on the Tc enhancement by 5% sodium addition was investigated for (Pb0.5Cd0.5)Sr2(Y1-xCax)Cu2 O7-δ(x = 0.3, 0.5) superconductors. The sodium free superconductors show only onset of superconductivity (Tc,onset), which increases from 23 to 49 K with increasing calcium content. The resistivity behaviour before Tc changes from semi-conducting to metallic nature. Addition of sodium leads to the observation of zero resistance (Tc.zero) at 25 K only for x = 0.5 sample, which is however lower than the Tc,zero of 30 K exhibited by the superconductor with x = 0.4 calcium content. The lowering of melting point and denser microstructure with larger grains were observed upon 5% sodium doping on (Pb0.5,Cd0.5)Sr2(Y0.6,Ca0.4)Cu2 O7-δ superconductor.
About the journal
JournalData powered by TypesetPhysica C: Superconductivity and its Applications
PublisherData powered by TypesetElsevier
ISSN09214534
Open AccessNo
Concepts (11)
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    Addition reactions
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    Annealing
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    Crystal microstructure
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    Grain size and shape
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    High temperature superconductors
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    Lead compounds
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    Melting
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    Semiconductor doping
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    Sodium compounds
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    SODIUM FREE SUPERCONDUCTORS
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    Oxide superconductors