Doping effect of Pr₆O₁₁ on superconductivity and flux pinning of MgB₂ bulk

Abstract

Abstract Bulk samples of MgB 2 doped with 0, 1, 3, and 5 wt% Pr 6 O 11 nanopowder were prepared using a solid‐state reaction route. The lattice constants of Pr 6 O 11 ‐doped MgB 2 systematically increase with increasing doping level, indicating a partial substitution of Pr for Mg in the crystal structure, and consequently, the superconducting transition temperature, T c , of MgB 2 is slightly suppressed. At a low doping level of 1 wt% Pr 6 O 11 , the critical current density, J c , and the irreversibility field, H irr are improved. However, at higher doping levels, Pr 6 O 11 doping seems harmful for the performance of MgB 2 in high magnetic fields. It is argued that the effect of the doping mechanism of Pr 6 O 11 on T c and J c is quite different from those of other rare‐earth elements, such as Y or Dy. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)