Effect of Ag2CO3 addition on the morphology and physical properties of Bi-based (2223) high-Tc superconductors

The effect of Ag2CO3 addition (0-25 wt%) on the Bi1.6Pb0.4Sr2Ca2Cu3O delta (Bi-2223) precursor powder has been investigated in terms of X-ray diffraction, scanning electron microscopy, dc electrical resistivity, critical temperature, ac magnetic susceptibility and critical current density. The samples were prepared by the conventional solid-state reaction method. The room temperature X-ray diffraction patterns of all the samples indicated the presence of large amount of Bi-(2223) phase along with minor amount of Bi-(2212) phase. The lattice structure of the material belongs to the orthorhombic unit cell. The volume fraction was estimated from the intensities of Bi-(2223) and Bi-(2212) phases. The sample with 5 wt% of added Ag shows the higher volume fraction of Bi-(2223) phase formed (86%). The dc electrical resistivity of all the samples decreases as the wt% of Ag increases. Both the onset critical T-c(onset) and zero electrical resistivity T-c(R = 0) temperatures were determined from the dc electrical resistivity and ac magnetic susceptibility measurements, which remains within the temperature range 110-113 +/- 1 K and 101-106 +/- 1 K respectively. Resistivity data agrees with ac magnetic susceptibility measurements. The critical current density for the 25 wt% Ag doped samples increased by three-times compared to the un-doped sample. (c) 2006 Elsevier B.V. All rights reserved.