  RE-Ba-Cu-O (RE denotes rare earth elements) single-grain superconductors have
garnered considerable attention owning to their ability to trap strong magnetic
field and self-stability for maglev. Here, we employed a modified melt-growth
method by adding liquid source (LS) to provide a liquid rich environment during
crystal growth. It further enables a significantly low maximum processing
temperature (Tmax) even approaching peritectic decomposition temperature. This
method was referred as the liquid source rich low Tmax (LS+LTmax) growth method
which combines the advantage of Top Seeded Infiltration Growth (TSIG) into Top
Seeded Melt-texture Growth (TSMG). The LS+LTmax method synergistically
regulates the perfect appearance and high superconducting performance in REBCO
single grains. The complementary role of liquid source and low Tmax on the
crystallization has been carefully investigated. Microstructure analysis
demonstrates that the LS+LTmax processed GdBCO single grains show clear
advantages of uniform distribution of RE3+ ions as well as RE211 particles. The
inhibition of Gd211 coarsening leads to improved pining properties. GdBCO
single-grain superconductors with diameter of 18 mm and 25 mm show maximum
trapped magnetic field of 0.746 T and 1.140 T at 77 K. These trapped fields are
significantly higher than those of conventional TSMG samples. Particularly, at
grain boundaries with reduced RE211 density superior flux pinning performance
has been observed. It indicates the existence of multiple pinning mechanisms at
these areas. The presented strategy provides essential LS+LTmax technology for
processing high performance single-grain superconductors with improved
reliability which is considered important for engineering applications.
