The investigation of electrical and mechanical properties of Pr doped Bi-2212 superconductor

In this study, we have investigated the effect of the praseodymium doping on structural, superconducting and mechanical properties of the Bi-2212 superconductors annealed ? 840 ? ^o C for 50 hour. The samples are prepared by the conventional solid-state reaction method that this method is the most widely used method for preparing high temperature superconductors. For comparison, undoped sample was prepared in the same conditions. The experimental works in this study consist of dc electrical resistivity measurement for electrical and superconducting properties, microhardness measurement for mechanic properties. Vickers microhardness, Young?s modulus, fracture toughness and yield strength values were calculated separately for doped and undoped samples. Later, experimental results of hardness measurements were analyzed using the Kick?s law, proportional sample resistance (PSR), modified proportional sample resistance (MPRS) model and the Hays- Kendall (HK) approach and the Hays- Kendall approach was determined as the most successful model. In addition to these, we have calculated the load independent hardness, Young?s modulus, fracture toughness and yield strength values of samples. Powder X-ray diffraction (XRD) for phase analyses and lattice parameters, and scanning electron microscopy (SEM) for microstructure examination. According to these results, Pr doping, in comparison with undoped samples, were decreased the lattice parameter c and grain size, T_c^onset values increased and microhardness values decreased with increasing Pr doping in comparison with undoped samples. As a result, by using all these measurements, to improved superconductivity properties and crystal structure of Bi-2212 superconductor with Pr doping were investigation in detail.