Current Density and Activation Energy of Bi-2223 Superconductors Synthesized Via Electrospinning

Abstract

Bismuth-based oxide superconductors, known as bismuth strontium calcium copper oxide were characterized in pellet form, and were synthesized via electrospinning subsequently via solid-state reaction with heat treatment. A sol-gel mixture was prepared consisting of PVP solution, dissolved in propionic acid, as well as Bi, Sr, Ca, and Cu acetates. The sol-gel was then subjected to electrospinning process and collected in film and flake form. Samples were heat treated at 120 °C to remove excess moisture, and then at 450 °C to remove PVP. Significant weight loss of the collected fiber sample was analyzed and represented by thermal gravimetric analysis at approximately 50% of the initial sample. The samples were ground and pressed at 0.9 GPa into pellets and heat treated again at 850 °C. Based on XRD, the samples contain major Bi-2223 phases of their volume fraction at 60%. The grain boundaries existing in the samples were a distribution of high and low-angled grain boundaries. Four-point probe measurements were conducted to investigate the critical transition temperature of samples. The T_c for Pb-doped sample was observed at 80 K and un doped at 68 K. The activation energy showed improvements for doped sample. Precursors added with Pb and un-doped contain similar Bi-2223 phases in pressed pellet form This highlights the potential of using electrospinning to synthesize functional Bi-2223 superconductors with or without doping with Pb.