Research on mechanical, structural and electrical properties of zirconium doped Bi-based superconducting ceramics

The aim of this study is to investigate influences of the zirconium (Zr) diffusion on the structural, morphological, mechanical, electrical and superconducting features of the Bi-2223 ceramic. The present study also covers in-depth understanding of correlations between the disorders and transition temperatures. The Zr diffusion was carried out via annealing process between 650 °C and 840 °C. Result have depicted that the Zr can easily diffuse into the deeper level of the Bi-ceramics and possible Zr/Sr substitution have occurred due to the driving force of high thermal energy. The Zr diffusion improves the crystallography of the Bi-2223 ceramic up to 800 °C annealing process. In addition, better intergranular couplings with smoother plate-like structure have been observed in surface morphology for the samples annealed at 800 °C. A significant improvement on the both basic electrical resistivity, hole carrier densities and critical temperatures with narrow transition was also obtained for the Zr surface-layered Bi-2223 ceramics after 800 °C annealing process. The obtained refinement of these critical features can be attributed to the formations of bipolaron in the superconducting clusters, optimum pairing mechanism, best crystal structure quality and ideal Cu-O2 interlayer coupling strengths and interaction between Zr diffused superconducting grains. It can be concluded that the Zr impurity diffusion at 800 °C is promising for the improvement of basic features of the Bi-2223 systems for future applications in superconductor technology.