Enhanced flux pinning in (Nd0.33Sm0.67)Ba2Cu3O7-delta melt-processed superconductors by Ar postannealing

High-quality binary (Nd0.33Sm0.67)Ba2Cu3O7-delta monodomain superconductors were fabricated by the combination of a compositional-controlled melt-proc essing technique in air and postannealing in Ar. Critical current densities over the whole field range were observed strongly dependent on Ar postanne aling while holding superconducting transition temperatures as high as 96 K . The suppressed chemical variation between the rare-earth element (RE: Nd, Sm) and Ba associated with disperse RE2BaCuOy (RE211) precipitate due to t he decomposition occurring in Ar postannealing was attributed to the modifi ed flux pinning. This makes Ar postannealing promising to process supercond uctors with desired properties for various applications. (C) 1999 American Institute of Physics. [S0003-6951(99)03528-7].