Effects of doping on the superconductivity of the Bi1.84Pb0.34Sr1.91Ca2.03Cu3.06Oy oxide

Abstract Effects of sintering atmosphere on the formation of the 2-2-2-3 phase in the Ag-doped and the Ag 2 O-doped PbBiSrCaCuO systems were investigated in three different atmospheres (pure oxygen, air and O 2 Ar = 1 13 ). The formation of the 2-2-2-3 phase is enhanced with increasing sintering time in air and under low oxygen partial pressure, but suppressed in pure oxygen. T c also increases with increasing sintering time, irrespective of the type of doping element and independent of their content up to 20 wt % Ag and 21.17 wt% Ag 2 O. A considerable interaction among superconducting phases and the Ag or Ag 2 O is not observed in all the atmospheres. The doped Ag is present as an isolated particle in the superconducting matrix, whereas the doped Ag 2 O is reduced to Ag metal phase and is also present as an isolated particle in the matrix.