Transport and Mechanical Properties of (Bi,Pb)-2223 Doped by PbF₂

This study examines the influence of PbF₂ addition on the electrical and the mechanical properties of Bi_1.8Pb_0.4Sr₂Ca_2.1Cu_3.2O_10+δ superconducting phase. Samples of nominal composition Bi_1.8Pb_0.4Sr₂Ca_2.1Cu_3.2O_10+δ-xF_x were prepared using solid-state reaction technique. The fluorine content x varied from 0.00 to 0.30 by step 0.05. The prepared samples were characterized by X-ray powder diffraction (XRD) and scanning electron microscope (SEM). The XRD investigation indicated that the fluorine enhanced the (Bi,Pb)-2223 phase formation up to x = 0.10. On the other hand, the high concentrations of fluorine retarded the phase formation. Granular investigation, by SEM, showed the grain size increased as x increased from x = 0.05 to 0.20 with more grain's orientation and inter-coupling between superconducting grains. The electrical resistivity measurements indicated that superconducting transition temperatures reached 114K for x up to 0.10. Additionally the transport critical current density at 77K and zero magnetic field have been reached ~700 A/cm², then suppressed for higher contents. Moreover, the samples exhibited higher Vickers micro-hardness at x = 0.10. The results were attributed to the role of partial replacement of Oxygen by fluorine in (Bi,Pb)-2223 superconducting phase.