The Ag-doped MgB2 bulk superconductors were prepared using a standard solid state processing. The addition of Ag to MgB2 powders during the sintering process was found to result in an important advantage, namely, the prevention/reduction of loss of Mg, a problem most commonly observed in the sintering of MgB2 bulk samples at elevated temperature and ambient pressures. The Ag-doped MgB2 sample had a distinct superconducting transition temperature around 39K, while the undoped MgB2 underwent only a very feeble transition to a diamagnetic superconducting state at around 39K. The normal conducting Ag regions in the MgB2 matrix acted as pinning centers resulting in the realization of high critical currents in the presence of magnetic fields.

Role of Silver Addition in the Synthesis of High Critical Current Density MgB2 Bulk Superconductors. D.Kumar, S.J.Pennycook, J.Narayan, H.Wang, A.Tiwari: Superconductor Science and Technology, 2003, 16, 455-8