Study of the Electrical and Structural/Micro structural Properties of Bi2-xAgxBa2-ySryCa2Cu3O10+? System

Abstract

This study included preparing samples of the compound  (Bi₂Ba₂Ca₂Cu₃O_10+?) by the reaction of the solid state under a hydrostatic pressure 8 ton/cm² and annealing temperature 840^oC . X-ray diffraction (XRD), scanning electron microscopy (SEM), dc electrical resistivity measurements by four point probe method were used to investigate the microstructural and superconducting properties of Bi¬2223 samples.  The X-rays diffraction study for the compound   (Bi₂Ba₂Ca₂Cu₃O_10+? ) showed that it has Tetragonal type of crystal structure .The partial replacement of the component Ag in Bi, and Sr component  in Ba simultaneously, the compound becomes (Bi_2-xAg_xBa_2-ySr_yCa₂Cu₃O_10+?) with (x ,y) values equal to (x= 0.2, y= 0.1, 0.2, 0.3,0.4). The study of the crystal structure test showed that the structure retains on the tetragonal type with a high Tc phases (2223), low Tc phase(2212) and impurity phases, and the critical temperature Tc steps-up from (125 K) to (137 K) at substitution rate (x= 0.2, y= 0.1). But at increasing the substitution rate for (y) and the stability of (x) rate more than (x= 0.2, y= 0.1), the temperature declines to (108 K). Finally, the microstructural of the samples has been studies and tested by Scanning Electron Microscope for knowing the components' rates in the compound; how the compound partial substitution affect in the components; and specifying the quantitative and qualitative rates of the components in the compound.

Keywords: Bi-based, Bi-2223, Partial Substitution, Crystal Structure, Bi-Ba-Ca-Cu-O, LT phase , HT phase