Microstructure and Superconducting Properties of YBCO Bulk Superconductors With RE Substitutions

The influence of RE (RE = Yb, Sm) substitutions on the microstructure and superconducting properties of Y-Ba-Cu-O (YBCO) bulk superconductors has been studied for different RE concentrations and their combinations. Precursor powders YBa
₂
Cu
₃
O
_7-δ
(Y-123), Y
₂
O
₃
and CeO
₂
were enriched with different amounts of Yb
₂
O
₃
and (or) Sm
₂
O
₃
powders with the aim to increase critical current density, i.e., Jc, in self-field as well as in higher magnetic fields, by introducing additional pinning centers. YBCO bulk superconductors with RE
₂
O
₃
addition were prepared by the optimized top-seeded melt-growth process in the form of single grains. Microstructure analysis revealed that RE
₂
O
₃
addition leads to a higher amount of smaller Y
₂
BaCuO
₅
(Y-211) particles, which is related to high critical current density (J
_c
~ 7 × 10
⁴
A/cm
²
) of the samples with RE
₂
O
₃
addition in low magnetic fields. In this paper, the effect of RE
₂
O
₃
addition on Y-211 particle size, critical temperature T
_c
, and critical current density J
_c
is reported.