Structure and electrical properties of lanthanum doped Bi_2Sr_2Ca_{2-x}La_xCu_3O_{10+ \delta} superconductor


Abstract: In this work we studied the effect of La-doping on phase purity, crystal structure and electrical resistivity of Bi_2Sr_2Ca_2Cu_3O_{10+\delta} 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 \rho_m. 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.

Keywords: Superconductors, electrical resistivity, critical temperature

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