Title :
The influence of structural defects on intra-granular critical currents of bulk MgB2
Author :
Serquis, A. ; Liao, X.Z. ; Civale, L. ; Zhu, Y.T. ; Coulter, J.Y. ; Peterson, D.E. ; Mueller, F.M.
Author_Institution :
Supercond. Technol. Center, Los Alamos Nat. Lab., NM, USA
fDate :
6/1/2003 12:00:00 AM
Abstract :
Bulk MgB2 samples were prepared under different synthesis conditions and analyzed by scanning and transmission electron microscopy. The critical current densities were determined from the magnetization versus magnetic field curves of bulk and powder-dispersed-in-epoxy samples. Results show that through a slow cooling process, the oxygen dissolved in bulk MgB2 at high synthesis temperatures can segregate and form nanometer-sized coherent precipitates of Mg(B,O)2 in the MgB2 matrix. Magnetization measurements indicate that these precipitates act as effective flux pinning centers and therefore significantly improve the intra-grain critical current density and its field dependence.
Keywords :
critical current density (superconductivity); flux pinning; grain boundary segregation; magnesium compounds; magnetisation; scanning electron microscopy; transmission electron microscopy; type II superconductors; Mg(B,O)2; MgB2; critical current densities; effective flux pinning centers; field dependence; high synthesis temperatures; intra-grain critical current density; intra-granular critical currents; magnetization; magnetization measurements; nanometer-sized coherent precipitates; powder-dispersed-in-epoxy; scanning electron microscopy; segregate; slow cooling process; structural defects; transmission electron microscopy; Cooling; Critical current; Critical current density; Density measurement; Magnetic analysis; Magnetic fields; Magnetization; Scanning electron microscopy; Temperature; Transmission electron microscopy;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
DOI :
10.1109/TASC.2003.812093
