Influence of diffusion-annealing time on the mechanical properties of bulk Bi$_{1.8}$Pb$_{0.35}$Sr$_{1.9}$Ca$_{2.1}$Cu$_{3}$O$_{y}$ superconductors diffusion-doped with Fe.

In order to investigate the role of Fe doping and diffusion-annealing duration on the mechanical and superconducting properties of Bi-Pb-Sr-Ca-Cu-O, Bi$_{1.8}$Pb$_{0.35}$Sr$_{1.9}$Ca$_{2.1}$Cu$_{3}$O$_{y}$ superconductors were prepared by standard solid-state reaction methods. Doping of Bi-2223 was carried out by means of iron diffusion during sintering from an evaporated iron film on pellets. The investigations consist of SEM, dc resistivity and hardness measurements. These measurements indicated that the Fe doping and diffusion-annealing time increased the T$_{c}$, J$_{c}$, Vickers hardness (H$_{0})$, Young's modulus(E), yield strength(Y), fracture toughness(K$_{IC})$ values and improved the grain connectivity. The mechanical properties of the samples were found to be load dependent and on the diffusion-annealing time. In addition, we calculated the load independent H$_{0}$, E, Y, and K$_{IC}$ of the samples. Possible reasons for the observed improvements in the superconducting and mechanical properties due to Fe diffusion are discussed.