Superconducting properties and microstructures of CeO2 doped YBa2Cu3O7−δ films fabricated by pulsed laser deposition

Abstract

Performance of REBa2Cu3O7−δ superconductors strongly depends on their microstructures and surface morphologies. Using a reel-to-reel pulsed laser deposition (PLD) system, the CeO2-doped YBa2Cu3O7−δ (CeO2-Y123) films were fabricated. Superconducting properties and microstructure of these films were systematically studied for the first time. The results showed that the relationship between the critical current (Ic) values and the deposition temperature depends on the doping content essentially. For all CeO2-doped films, the Ic values increase at first and then decrease with increasing the deposition temperatures. The evolution of surface morphologies should take responsibility for this phenomenon. The optimum deposition temperature of 1 and 2 mol. % CeO2-doped Y123 films is higher than that of 3 mol. % CeO2 doped ones. The substitutions of the Y atoms by Ce atoms are considered as the determinative factor. Furthermore, the in-plane rotation of the crystalline grain orientation on the surface of the CeO2-Y123 films was observed. We think that not only the lattice mismatch, but also the density of dangling bonds contributes to this distinctive phenomenon.