Essential role of liquid phase on melt-processed GdBCO single-grain superconductors.

We systematically investigated the role of additional liquid source (LS) which creates a liquid-rich nucleation environment and influences the growth kinetic energy. It enables a significant decrease in maximum processing temperature (T max) even close to the peritectic decomposition temperature (T p), hence optimizing the distribution and size of the Gd 2 BaCuO 5 (Gd211) particles. By exploiting this combined LS and low T max (LS+LT max) growth method, the performance of GdBa 2 Cu 3 O 7-δ (GdBCO) single-grain superconductors has been greatly improved. Therefore, the maximum trapped magnetic fields reach 0.746 T and 1.140 T for the 18- and 25-mm-diameter samples at 77 K. Meanwhile, superior flux pinning performance has been observed at the growth section boundaries (GSBs) with a decreased density of Gd211 particles in the LS+LT max samples. These results indicate that the LS+LT max technology can fabricate high-performance single-grain superconductors with improved reliability which is considered important for engineering applications. [ABSTRACT FROM AUTHOR]