Structure and electrical properties of lanthanum doped $Bi_2Sr_2Ca_{2-x} La_x Cu_3 O_{10+delta}$ superconductor

Abstract

In this work we studied the effect of La-doping on phase purity, crystal structure and electrical resistivity of Bi2 Sr2 Ca2 Cu3O10+δ superconductor, synthesized by usual solid state reaction method. The X-ray florescence (XRF) show the stoichiometry of samples and X-ray diffraction (XRD) analysis showed the change of structure from orthorhombic to tetragonal by increasing La doping. It was found that the change of lanthanum concentrations of all our samples produce a change in the oxygen content, the ratio of lattice parameters c/a and mass density ρm. Electrical resistivity, using the four-probe technique, was used to find the critical temperature $T_c$ and to put in evidence metallic and semiconducting behavior in normal state.