Transmission electron microscope characterization of dislocation structure in BiSrCaCu superconducting oxide

The recently discovered new class of BiSrCaCu superconducting oxide with Tc as high as 120 K has generated a new wave of intense research on the high Tc superconducting systems. in this presentation, we report the results of a transmission electron microscope (TEM) study of dislocation structure in a superconducting BiSrCaCuO compound.The superconducting oxide with nominal composition of Bi2Sr2CaCu2Oy was prepared by quenching or slow cooling the solid-state-reaction sintered specimens which had been calcined from mixed Bi2O3, CaCo3, CuO, and SrCO3 powders. Thin foils for TEM examinations were generally prepared by grinding in a pestle and mortar. A JEOL-2000FX transmission electron microscope operating at 200 keV was used.The quencehed specimens exhibited Tc-onset at 120 K and Tc-zero at 90 K, whereas the slowly cooled specimens showed Tc-onset at 104 K and Tc-zero at 75 K. X-ray diffraction and TEM/EDS data showed that the sintered samples were mainly of a phase with nominal composition Bi2Sr2CaCu2Oy, XRD, SAD and CBED identified that the crystal structure is orthorhombic with a=0.541 nm, b=2.69 nm, and c=3.07 nm.