Scandium and gallium substitution effects in the (Y_1-xSc_x)Ba₂Cu₄O₈ and (Y_1-xGa_x)Ba₂Cu₄O₈ superconducting oxides

In this study scandium and gallium substitution effects in the YBa₂Cu₄O₈ (Y-124) superconducting cuprate have been investigated. The superconducting (Y_1-xSc_x)Ba₂Cu₄O₈ and (Y_1-xGa_x)Ba₂Cu₄O₈ (x = 0.0, 0.05, 0.1 and 0.2) compounds have been synthesized using a simple sol-gel synthesis technique. The obtained oxides were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TG) and resistivity measurements. The X-ray diffraction patterns of the samples with x = 0.0, 0.05, and 0.1 showed that the single phase (Y_1-xSc_x)Ba₂Cu₄O₈ and (Y_1-xGa_x)Ba₂Cu₄O₈ compounds have formed. Moreover, the XRD results are completely supported by TG measurements. The results of resistivity measurements for the (Y_1-xSc_x)Ba₂Cu₄O₈ samples showed that the onset critical temperature of superconductivity for these samples slightly increased. Contrarily, T_C for the (Y_1-xGa_x)Ba₂Cu₄O₈ samples decreased monotonically with the increasing amount of gallium.