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Superconducting properties ofY1-xTbxBa 2Cu3O7-δ and Y1-xTb xSr2Cu2.7Mo0.3O7-δ

Mirshamsi, S ; Sharif University of Technology | 2010

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  1. Type of Document: Article
  2. DOI: 10.1142/S0217984910022494
  3. Publisher: 2010
  4. Abstract:
  5. We have investigated the effect of Tb substitution for Y in both YBa 2Cu3O7-δ and the more stabilized YSr 2Cu2.7Mo0.3O7-δ systems. Adding Mo has been shown to stabilize the Tb-doped systems. The samples of Y1-xTbxBa2Cu3O7-δ with x=0.0, 0.1, 0.15, 0.2, 0.3, 0.35, 0.4, 0.5, 0.55, and 0.6, and of Y 1-xTbxSr2Cu2.7Mo0.3O 7-δ with x=0.0, 0.2, 0.4, 0.6, and 0.8 have been prepared by the standard solid-state reaction technique. The superconducting transition occurs only with x=0-0.5 for the Ba-based samples, and with x=0-0.8 for the Sr-based samples. The structural parameter identification and phase determination of the samples have been carried out by the Rietveld analysis of the X-ray diffraction patterns, which indicates that Tb does not enter in the structure of the Ba-based 123 phase, while in the Sr-based 123 structure Tb enters in the structure and substitutes for Y. In the Y1-xTb xBa2Cu3O7-δ samples, a new secondary TbBaO3 phase forms; and by increasing the amount of Tb, the secondary phase increases as the Y123 phase decreases. But, for the Y 1-xTbxSr2Cu2.7Mo0.3O 7-δ samples, by increasing the amount of Tb doping, no impurity phase is detected in the XRD patterns. For both groups of samples, by increasing the amount of Tb, the normal resistivity increases, and the metallic behavior of the resistivity changes to semiconducting behavior. The magnetoresistance of Y1-xTbxBa2Cu 3O7-δ was measured in different magnetic fields. The width of transition for the same values of magnetic field increases with the increase of Tb doping, indicating that with the increase of Tb, grains link weaker due to the increase in the amount of the secondary TbBaO3 phase. The pinning energy has also been evaluated based on the thermally activated phase creep model
  6. Keywords:
  7. Electrical properties ; Magnetoresistance ; Pinning energy ; Substitution ; Superconducting properties ; Tb substitution ; YBCO
  8. Source: Modern Physics Letters B ; Volume 24, Issue 4-5 , 2010 , Pages 419-429 ; 02179849 (ISSN)
  9. URL: http://www.worldscientific.com/doi/abs/10.1142/S0217984910022494