Investigation of structural, superconducting and mechanical properties of Co/Cu substituted YBCO-358 ceramic composites

In this study, we have examined the structural, superconducting and mechanical properties of Y₃Ba₅Cu_8−xCo_xO_{18 − δ} system (x = 0, 0.05, 0.1, 0.15, 0.2 and 0.5), which is produced by conventional solid-state reaction method. Produced samples have been examined using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), Vicker’s hardness (H_v) and electrical resistance measurement (R–T). According to the XRD patterns, we have obtained that the Co nanopowder doping has been caused some changes on the average grain size, characteristic peak intensities and lattice parameters of the Y₃Ba₅Cu₈O_{18 − δ} crystal system. Furthermore, according to the electrical resistance measurements, the critical temperature (T_c) values of all the samples have tended to decrease constantly with the increment in the doping ratio in the Y358 crystal structure. As for the variation in the microhardness parameters of superconducting materials, the H_v parameters and other related computations (Young’s modulus and yield strengths) have been found to increase regularly with the Co/Cu substitution level. Besides, the characteristic H_v curves have confirmed that the whole bulk of Bi-2212 samples showed untypical reverse indentation size effect (RISE) behavior.