Flux pinning properties of Yb substituted (Bi,Pb)-2212 superconductor

详细信息	查看全文 | 推荐本文 |

• 作者：A. Biju ; P.M. Sarun ; R.P. Aloysius ; U. Syamaprasad
• 关键词：Superconductor ; Solid state reactions ; Electrical transport ; Flux pinning and creep
• 刊名：Journal of Alloys and Compounds
• 出版年：2008
• 期刊代码：45_09258388
• 类别：ms
• 出版时间：24 April 2008
• 卷：454
• 期：1-2
• 页码：46-51
• 文件大小：884 K

摘要

A systematic study on phase evolution, bulk density, resistivity, T_C, J_C, and J_C–B characteristics of pure and Yb substituted (Bi,Pb)-2212 samples at different cationic sites (Bi, Ca, Sr) has been carried out. The results show that there is a substantial improvement in the overall superconducting properties, particularly the T_C, J_C, and J_C–B characteristics of the Yb substituted samples. Further, it is observed that there is a significant shift in the peak value of the bulk pinning force density F_pmax towards higher magnetic fields when Yb is substituted at different cationic sites, indicative of the enhanced flux pinning strength in these samples. All the substituted samples show almost identical microstructure, but are distinctly different from pure (Bi,Pb)-2212. The natural layered growth mechanism of (Bi,Pb)-2212 is disrupted by grain growth, and coarsening in random directions. The substituted Yb atoms enter into the corresponding sites in (Bi,Pb)-2212, which create inhomogeneities in the crystal structure, decrease the hole concentration, and may produce point like defects. These defects act as the pinning centers. There is also the possibility of formation of nanoscale secondary phases, which can act as pinning centers.