Enhanced critical currents by CeO2 additions in directionally solidified YBa2Cu3O7

Abstract
The microstructure and critical currents of superconducting YBa2Cu3O7-Y2BaCuO5 composites with small CeO2 additions prepared using a directional solidification procedure have been investigated. The small CeO2 additions cause the decomposition of the Y2BaCuO5 phase leading to the formation of Y2O3 and BaCeO3. Experimental evidence is given for the subsequent nucleation of the Y2BaCuO5 phase on the Y2O3 particles. This new decomposition-nucleation mechanism leads to textured YBa2Cu3O7 having enhanced critical currents. An addition of 0.3 wt % CeO2 can increase Jabc by a factor of 2 in samples having similar concentration of Y2BaCuO5 precipitates. Critical currents above 105 A/cm2 at 77 K and zero field are obtained by this method.