Effect of oxygen partial pressure on the morphology and properties of Ce doped YBCO films fabricated by a MOCVD process

Abstract

Rare-earth (RE) (e.g. Sm, Dy, Ce, etc.) doping has been widely investigated to improve critical current density ( J c ) of YBa 2Cu 3O 7− X (YBCO) coated conductors (CC). Oxygen partial pressure is known to be a key parameter in terms of affecting the J c of YBCO films. In this work, the effect of oxygen partial pressure on the microstructure and J c of a Ce doped YBCO film was examined. Ce doped YBCO films were deposited on (1 0 0) SrTiO 3 (STO) single crystal substrates at oxygen partial pressures of 2.5, 5.0, and 10.0 Torr using a metal organic chemical vapor deposition (MOCVD) method. Due to the enhanced migration of surface adatoms under reduced oxygen partial pressure, a 1 wt% Ce doped YBCO film had a stoichiometric, dense surface. In addition, the zero-field J c (at 77 K) of the 1 wt% Ce doped YBCO film deposited at reduced oxygen partial pressure was increased. Irrespective of the amount of Ce, the Ce doped YBCO film showed an increased zero-field J c (at 77 K) under reduced oxygen partial pressure.