Phase equilibria of the Ba–Sm–Y–Cu–O system for coated conductor applications

The complex phase relationships near the BaO-poor region of the quaternary Ba–Sm–Y–Cu–O oxide system prepared in pure air (O2ppO2=22 kPa, 950 °C) and in 0.1% O2 (O2ppO2=100 Pa, 810 °C) have been determined. This investigation also included the subsolidus compatibilities in ten subsystems (Ba–Sm–Y–O, Ba–Sm–Cu–O, Ba–Y–Cu–O, Sm–Y–Cu–O, Ba–Sm–O, Ba–Y–O, Ba–Cu–O, Sm–Y–O, Sm–Cu–O, and Y–Cu–O), and the homogeneity range of five solid solutions (Ba(SmxY2−x)CuO5, (Sm,Y)2O3, (Sm,Y)2CuO4, (Y,Sm)2Cu2O5, and Ba(Sm,Y)2O4). The single phase range of the superconductor solid solution, (Ba2−xSmx)(Sm1−yYy)Cu3O6+z, and the phase compatibilities in its vicinity, which are particularly important for processing, are described in detail. The phase equilibrium data of the Ba–Sm–Y–Cu–O system will enable the improvement of the intrinsic superconducting properties of second-generation wires, and facilitate the flux-pinning process.