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Nd1+XBa2-XCu3O7-δ Bulk Superconductor by Zone-melt Process

  • Soh, Dea-Wha (Department of Electronics Engineering, Myongji University.) ;
  • Guo, Fan-Zhan (Materials and Metallurgy School, Northeastern University)
  • Published : 2002.09.01

Abstract

Two kinds of $Nd_{1+X}Ba_{2-X}Cu_3O_{7-{\delta}}$, the sintering samples and zone melting samples, were heat-treated under pure Ar at 950$^{circ}C$. The substitution of Nd ion for Ba ion in the $Nd_{1+X}Ba_{2-X}Cu_3O_{7-{\delta}}$ before and after the heat treatment was investigated by XRD. In order to confirm the effects of the heat treatment, the Tc and Jc of samples with/without the heat treatment under Ar were comparatively studied. $Nd_{1+X}Ba_{2-X}Cu_3O_{7-{\delta}}$ samples were oxygenated under pure oxygen at $300^{circ}C$. From the XRD pattern it was found that the sample with x<0.4 was transferred from tetragonal phase to orthorhombic phase after the oxygenation, while the sample with x>0.4 did not show the phase transition even after a long time oxygenation. Therefore, the low oxygen partial pressure (Ar+1 % O$_2$) was used for the ambient atmosphere of the zone-melting samples, which could reduce the melting temperature and depress the substitution of Nd for Ba. After the improvement in the zone-melting process, the Jc value was increased to 2 x $10^4$A/$cm^2$ (0 T, 78 K). The particle orientation and the structure of zone-melted NdBaCuO were studied by the XRD and SEM analysis.

Keywords

References

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