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

High-quality binary ${\mathrm{(Nd}}_{\mathrm{0.33}}{\mathrm{Sm}}_{\mathrm{0.67}}{\mathrm{)Ba}}_{\mathrm{2}}{\mathrm{Cu}}_{\mathrm{3}}{\mathrm{O}}_{\mathrm{7-\delta }}$ monodomain superconductors were fabricated by the combination of a compositional-controlled melt-processing technique in air and postannealing in Ar. Critical current densities over the whole field range were observed strongly dependent on Ar postannealing 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 ${\mathrm{RE}}_{\mathrm{2}}{\mathrm{BaCuO}}_y$ (RE211) precipitate due to the decomposition occurring in Ar postannealing was attributed to the modified flux pinning. This makes Ar postannealing promising to process superconductors with desired properties for various applications.