Effect of initial composition on distribution of RE211 (422) particles in RE123 superconductors

Abstract

Microstructure in melt-textured bulk RE1Ba2Cu3O6+d crystals (RE123; RE = Sm, Nd) was investigated, changing the initial composition from the tie-line composition of RE123–Sm2Ba1Cu1O5 (Sm211)/Nd4Ba2Cu2O10 (Nd422) to the Ba-enriched side. It was found that the Sm211/Nd422 particle size decreased in the liquid with increasing the Ba/Cu ratio of the initial composition, and this tendency was also found in the grown Sm123 crystals. Composition of the Sm123 grown crystal could be controlled by selecting the Ba-enriched initial composition to obtain an almost stoichiometric compound, which resulted in higher Tc values. Furthermore, the Jc values also increased under low magnetic fields due to the significant decrease of Sm211 particle size. Therefore, changing the initial composition toward the Ba-enriched side was found to be a new process to enhance both Jc and Tc values simultaneously.