Comparisons of the microstructure and superconducting properties in Y–Ba–Cu–O single-grain superconductors grown with different liquid sources: The influence of element doping through liquid infiltration

Abstract

Based on the top-seed infiltration and growth (TSIG) technique, two Y–Ba–Cu–O (YBCO) single-grain samples were successfully grown with two different kinds of liquid sources: Y2O3+10BaO+16CuO and Yb2O3+10BaO+16CuO, labeled as Y-LS and Yb-LS respectively, and systematical comparisons of their microstructure and superconducting properties were carried out. Microstructural observations indicate that the Yb-LS sample exhibits both the micro-sized Y2BaCuO5 (Y-211) particles and the nano-sized Y-211 inclusions with smaller sizes than the Y-LS sample, and the energy dispersive spectrometry (EDS) result confirms the existence of Yb element with a concentration up to 0.46wt% in Yb-LS processed sample. Measurements of superconducting properties showed that, a slightly higher levitation force (29.09N) and a slightly reduced Tc (90.3K) were observed in the Yb-LS sample, compared with the result (28.54N and 90.8K) in Y-LS sample. While for Jc property, both a higher zero-field Jc of 8.41×104A/cm2 and an obvious peak effect of 4.33×104A/cm2 at a higher field of 1.4T were observed in the Yb-LS sample, indicating the existence of stronger δl-type pinning from smaller Y-211 particles/inclusions, as well as stronger δTc-type pinning from the spatial fluctuations in matrix composition. The results prove the positive impact of the diffused Yb element on YBCO bulk superconductor and validate the element diffusion-doping route through the liquid infiltration.