Superconducting properties of powder-in-tube MgB2 tapes without and withWSi2 addition

We fabricated Fe-sheathed MgB2 tapes with and without WSi2-doping through the in situ powder-in-tube method. Heat treatment was performed at 600 degreesC for 1 h. These heat treatment conditions of lower temperature and short heating time are advantageous from viewpoint of practical fabrication processes. Compared to the undoped samples, the transport critical current density at 4.2 K increased significantly by the 5 at.% addition. The microstructure observations indicate that the intergrain connectivity of WSi2-doped tapes was improved, which might be responsible for the enhancement of J(c). Furthermore, the J(c)-B curves of doped tapes show better performance in higher magnetic fields, suggesting that pinning centers effective in a high-field region were possibly introduced. (C) 2004 Elsevier B.V. All rights reserved.