Improved Superconducting Properties of YBCO Melt-Solidified Bulks by Addition of Ba–Cu–O–Cl

In order to improve critical current properties for REBCO melt-solidified bulks, dilute addition of Ba
₂
Cu
₃
O
₄
Cl
₂
up to 5.0 mol% against starting Y123 powder was attempted in the synthesis of YBCO bulk samples. The addition of Ba
₂
Cu
₃
O
₄
Cl
₂
enhanced J
_c
at 77 K and the homogeneity of J
_c
in the bulk. Microstructural observation by TEM revealed that stacking faults parallel to the ab-planes were confirmed in the Y123 matrix of a Ba
₂
Cu
₃
O
₄
Cl
₂
-free bulk, whereas they were hardly observed in a 0.5 mol% Ba
₂
Cu
₃
O
₄
Cl
₂
-added one. It was suggested that the addition of Ba
₂
Cu
₃
O
₄
Cl
₂
can enhance crystallinity of the Y123 superconducting phase and improve homogeneity of YBCO bulks.