Investigation of Zr nanoparticle effects on structural phase stability, micro strains, and flux pinning in BSCCO-Zr/Cu doped HTSC

In this research, the resistivity of the Bi۱.۶۶Pb۰.۳۴Sr۲Ca۲Cu۳-xZrxO۱۰+δ (Bi-۲۲۲۳) polycrystalline samples (x=۰.۰, ۰.۰۰۲, ۰.۰۰۷۵, and ۰.۰۱) synthesized by the sol-gel method, has been investigated under magnetic fields. Also, the structural and morphological properties of ceramic superconductors have been studied by using Xray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) measurements. It is found that the Bi-۲۲۲۳ structural phase was formed more than other phases in the synthesized samples for x≤۰.۰۰۷۵. Based on the resistivity measurements, it is understood that the TC decreases with the increase in the Zr doping and the second superconducting transition is seen for the x≥۰.۰۰۷۵. The thermally activated flux creep (TAFC) model has been investigated in synthesized ceramic superconductors. Furthermore, the magneto resistivity behavior of all samples has been analyzed to determine the dependence of the pinning energy with applied magnetic fields and Zr doping. It is found that the pinning energy remarkably decreases with the rise of the Zr doping. Therefore, the creeping of vortices and crossing the energy barrier occur more easily, thus the pinning energy is reduced by increasing the Zr doping. Moreover, a good agreement between the modified TAFC model and the experimental data is concluded for the synthesized compounds.