Effect of Zn doping in Bi(Pb)-2212 superconducting ceramics

The subject of substitution in the high‐Tc superconductors has received a great deal of interest. Substitution of bismuth by lead stabilizes and purifies the superconducting phase in Bi2223 and enhances Tc in Bi2212 [1–5]. The substitution of Cu by magnetic or non magnetic element such as Fe, Ni, Co or Zn degrades significantly Tc [6, 7]. The substitution by Zn is difficult because the amount that can be dissolved is limited. Samples of Bi1.6Pb0.4Sr2CaCu2‐yZnyO8+d (0 ≤ y ≤ 0.06) were prepared by a solid‐state reaction method. The samples have been characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM) and AC susceptibility versus temperature measurements. Structural analysis shows that the obtained crystalline structure is mainly tetragonal with a c‐axis lattice parameter decreasing with Zn content. AC susceptibility measurements show that the Zn doping decreases the superconducting volume fraction in the samples. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)