Superconducting properties and microstructures of Er–Ba–Cu–O superconductor

Abstract

The growth rate of Er–Ba–Cu–O bulk superconductor as a function of undercooling was investigated using an isothermal solidification technique. The behaviour of the growth rate of Er–Ba–Cu–O under various undercooling was similar to that of Y–Ba–Cu–O. Furthermore, macro-segregation of Er211 was also observed in the a and c growth regions. However, macro-segregation of Er211 was not observed in the Er123 crystal fabricated by a continual slow cooling method far from the seed crystal. The optimum concentration of Er211 was determined to be Er123:Er211 = 3:1 on the basis of microstructure analysis and SQUID measurements. Furthermore, the trapped field capability as well as the critical current density of Er–Ba–Cu–O bulk superconductor with an optimum composition fabricated by a continual slow cooling method employing very small particles of Er211 was dramatically improved.