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 JG) 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. T-C for the (Y1-xGax)Ba2Cu4O8 samples decreased monotonically with the increasing amount of gallium. (C) 2009 Elsevier B.V. All rights reserved.