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In order to investigate the role of Au doping and diffusion-annealing duration on the mechanical properties of Bi–Pb–Sr–Ca–Cu–O, Bi1.8Pb0.35Sr1.9Ca2.1Cu3Oy superconductors were prepared by standard solid-state reaction methods. Doping of Bi-2223 was carried out by means of gold diffusion during sintering from an evaporated gold film on pellets. The effect of the diffusion-annealing duration on the mechanical and superconducting properties of these compounds was investigated using scanning electron microscopy, dc resistivity and hardness measurements. These measurements indicated that the Au doping and diffusion-annealing time increased the superconducting transition temperature, Vickers hardness, Young’s modulus, yield strength, fracture toughness values and improved the grain connectivity. The mechanical properties of the samples were found to be load dependent. In addition, we calculated the load independent hardness, Young’s modulus, yield strength and fracture toughness of the samples. These mechanical properties of the Au-doped samples were dependent on the diffusion-annealing time. Possible reasons for the observed improvements in the superconducting and mechanical properties due to Au diffusion are discussed.

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This study deals with the effect of Pr 2 O 3 addition on the structural, superconducting and mechanical properties of Bi-2212 superconductor by means of X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), electron dispersive X-ray (EDX), Vickers microhardness and resistivity measurements. The samples studied are prepared using the standard solid-state reaction method. Onset transition temperatures (T c onset ) of the samples are estimated from the dc resistivity measurements. Furthermore, the phase ratio and lattice parameters a and c are determined from XRD patterns when the microstructure, surface morphology and element composition analyses of the samples are investigated by SEM and EDX measurements, respectively. Additionally, vickers microhardness, elastic modulus, yield strength and fracture toughness values of the samples are deduced from microhardness measurements. It is found that T c onset values of the samples increase from 87 to 97 K with the Pr 2 O 3 addition. According to the refinement of cell parameters done by considering the structural modulation, the doping is confirmed by both an increase of the lattice parameter a and a decrease of the cell parameter c of the samples in comparison with that of the pure sample. As for SEM measurements, it is obtained that the surface morphology and grain connectivity degrade with the increase of the Pr 2 O 3 addition. Moreover, EDX images show that the elements used for the preparation of samples distribute homogeneously and the Pr atoms enter into the crystal structure by replacing Sr atoms. To sum up, the Pr 2 O 3 addition is found to suppress the mechanical, microstructural and superconducting properties of the Bi-2212 superconductor.