Fabrication of single crystalline Bi-2212 whisker with addition of Sb 2O 3 into the Bi 2Sr 2Ca 2Cu 3O x system and their thermal, structural and superconducting properties

Abstract

Single crystalline Bi-based superconducting whiskers have been fabricated from a melt quenched Bi 2SbSr 2Ca 2Cu 3O x precursor using suitable heat treatment cycles. Whiskers fabricated in this study have 6–15 μm thickness, 60–95 μm width and 1–3 mm length. Crystallization activation energy of the material fabricated was calculated to be 609 kJmol −1 by Kissinger method. Structural and micro-structural changes with the heating treatment cycles were analyzed by XRD and SEM-EDX. It was found that whiskers have pure c-axis oriented single crystalline Bi 2Sr 2CaCu 2O x (Bi-2212) phase with very smooth surface and without cracks and dislocations. Sb ions did not diffuse directly to the structure of whiskers. But Sb ions added to the system caused to decrease the number of whiskers. Temperature dependence of resistivity was analyzed along both the a- and c-axis. The superconducting transition temperature, T c , of the whiskers was found to be 93.8 K for the a-axis resistivity and 90.9 K for the c-axis resistivity, respectively. The transport critical current density, J c t r a n s was found as 2.6 × 10 5 A/cm 2 at 10 and 1.1 × 10 5 at 70 K. Magnetization hysteresis ( M–H) was investigated at three different temperatures (10, 20 and 30 K). Magnetic critical current densities, J c m a g , of whiskers were determined using the Bean’s Model.