Effect Of Co-Doping By Pb And La On Structural And Magnetic Properties Of Bi2212 Superconducting Ceramics

Doping the Bi2212 phase by Pb usually results in an enhancement of the pinning properties and the T-c. Using elements other than Bi and/or other sites one may obtain opposite results. In this work we present the effect on structural and magnetic properties of Bi2212 superconducting ceramics when co-doping with La and Pb is used. Bi1.4Pb0.6Sr2Ca1-xLaxCu2O8+delta (0 <= x <= 0.025) superconducting ceramic samples were prepared using a solid-state reaction method. Structural and magnetic characterizations were made by means of X-ray diffraction, scanning electron microscopy and AC susceptibility measurements. The obtained crystalline structure is mainly tetragonal with a c-axis lattice parameter decreasing with La content. Substitution by La reduces the fraction content of the parasitic phase Bi2201 and the size of the grains. The transition temperature T-c is enhanced quasi linearly with the La content and the superconducting volume fraction has a maximum for x = 0.01.