Scandium and gallium substitution effects in the (Y1−xScx)Ba2Cu4O8 and (Y1−xGax)Ba2Cu4O8 superconducting oxides

In this study scandium and gallium substitution effects in the YBa2Cu4O8 (Y-124) superconducting cuprate have been investigated. The superconducting (Y1−xScx)Ba2Cu4O8 and (Y1−xGax)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 (Y1−xScx)Ba2Cu4O8 and (Y1−xGax)Ba2Cu4O8 compounds have formed. Moreover, the XRD results are completely supported by TG measurements. The results of resistivity measurements for the (Y1−xScx)Ba2Cu4O8 samples showed that the onset critical temperature of superconductivity for these samples slightly increased. Contrarily, TC for the (Y1−xGax)Ba2Cu4O8 samples decreased monotonically with the increasing amount of gallium.