Influence of CeO ₂ on microstructure, cracking and trapped field of TSIG YBCO single-grain superconductors

Abstract YBCO bulk single-grain samples with and without cerium oxide addition, were prepared by the two-step top seeded infiltration growth. The microstructure observations showed that cerium oxide addition led to formation of small Y 2 BaCuO 5 (Y211) particles in the YBa 2 Cu 3 O 7 single-grain matix. On the other hand, the sample without cerium oxide addition exhibited clusters of large Y211 particles. Observed difference in Y211 paricles led to significantly different size of a/c-oxygenation cracks. While the mean length of a/c-cracks in the sample with cerium oxide addition was several hundred micrometers, it was smaller than 50 μ m in the sample without cerium oxide addition. It was shown that the clusters of large Y211 particles can effectively prevent extension of oxygenation a/c-cracks. The trapped magnetic field measured at 77 K is shown.