The characterization of structural, electric and mechanical properties of Co and CoFe2O4 doped polycrystal YBCO-123 superconductors produced by sol-gel and solid state reaction methods

In this study, YBa2Cu3-x(Co)xO7-δ and YBa2Cu3-x(CoFe2O4)xO7-δ superconductor samples were produced by using solid state reaction and sol-gel methods (x= 0, 0.05, 0.10 ve 0.20). In the preparation of the samples; oxide based compounds were used for the solid state reaction method, while acetate based compounds were used in the sol-gel method. All samples were sintered at 930 °C for 24 hours and 5 hours at 500 °C in oxygen atmosphere. X-ray diffraction (XRD) patterns, scanning electron microscopy (SEM) images, energy distribution spectroscopy (EDS) data were analyzed in order to determine the structural properties of the produced samples. In addition, temperature-dependent resistance (R-T) and Vickers microhardness measurements were performed to determine electrical and mechanical properties. XRD results showed that the sample was orthorhombic, and all samples showed superconductive properties in electrical measurement results. For the samples produced by both methods, the doping process reduced the superconducting critical temperature value. In addition, changes in Vickers microhardness values were investigated in detailed. As a result of the microhardness analysis, it was seen that while the microhardness behavior of the Co doped samples did not change, the hardness behaviors of the CoFe2O4 doped samples was changed. While the microhardness behavior of undoped sample was RISE, CoFe2O4 doped samples exhibited ISE behavior.