Effects of BCO₃ Addition on the Formation and Properties of the Bi-Based Superconductors

Abstract

The effects of the BCO₃ addition on the formation and properties of the Bi-based superconductors were studied. Phase identification, and structural and microstructural analyses were carried out using the powder X-ray diffraction method (XRD), scanning electron microscopy (SEM/EDX), AC magnetic susceptibility and resistivity measurements. The experiment results showed an increase of the superconducting phase content (BCO₃) with x=0.01 and all samples doped with B contain the 2212 phase. In the BCO₃ added samples (with x=0.01), the c lattice parameter decreased slightly from the nonadded sample showing the possibility of B incorporating into the crystal structure of the Bi-2212 phase. The variation in cell parameters is due to the difference in the ionic radii of B (0.2 Å) and Ca (1.06 Å). The SEM observation showed whisker grains, which are randomly distributed. The microstructural change is due to the addition of B. From the resistivity measurement, the $T_{\mathrm{c}}^{\mathrm{onset}}$ was found to be increased by 4 K for the doped sample compared to the undoped sample. An improvement of the normal state conductivity is obtained with a small amount of the addition (0.01). In the normal state, all the samples exhibit a metallic behavior.