Size effect of Y211 additions in Sm–Ba–Cu–O materials

Abstract

Our previous studies indicate that small additions of nano-scale RE2BaCuO5 (RE211, RE: rare elements) form nano-sized compositional fluctuations during the melt-growth process and thus act as field induced pinning centres. The solubility, peritectic temperature, and atomic size of these nmRE211 additives alter the Jc–H performance. To further reveal the effect of size and amount of RE211 additives, in this study, Y2Ba1Cu1O5 (Y211) particles of two different sizes, micro-scale (µm) and nano-scale (nm), were used. The superconducting results indicate that the contribution of Jc in high field regions is larger in nmY211 than µmY 211. The microstructure results imply that µmY 211 particles tend to form Y-rich regions in the core shell, while nmY211 particles tend to produce regions with Y fluctuations and high defect density. These different results are attributed to the reactions between the Y211 additions and the 123 matrix during the melt-textured growth process.