Role of diffusion-annealing time on the mechanical properties of bulk Bi-2223 superconductors diffusion-doped with Au

Abstract

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.