INVESTIGATIONS ON BaO_2 ADDITIONS IN Ag-CLAD Bi_2Sr_2CaCu_2O_x CONDUCTORS

摘要

The influence of the addition of BaO_2 on magnetic and transport properties of Bi_2Sr_2CaCu_2O_x superconductors was studied. Several compositions with varying BaO_2 fractions were investigated. Both bulk samples and Ag-clad wires were fabricated for every composition. Differential thermal analysis and x-ray diffraction measurements showed a reaction between BaO_2 and the precursor, while microstructural investigations revealed that the Ba remained homogeneously distributed in the Bi-2212. Magnetization measurements using SQUID and vibrating sample magnetometer showed improved flux pinning in the doped samples. Heat treatment process was varied to optimize the critical current densities. High current densities were achieved at high magnetic fields.