Effects of ionic doping on superconducting properties of melt texturedYBa2(Cu1−xMx)3O7−δ (M = Co,Ni, Zn or Ga) large grains

Abstract

The work reported in this paper aims at a better understandingof doping effects on high temperature superconductingYBa2Cu3O7−δ (YBCO or M-doped YBCO), in the form of large grains, fabricated by the topseeded melt-growth process. The study focused on the performance of YBCO largegrains doped with Co, Ga, Ni and Zn substituting for the Cu site. The rate ofTc suppression with dopant concentration varies significantly among different dopants.Zn doping shows the highest depression rate, followed by Ni, Ga and Co doping.This we attribute to the fact that Zn and Ni substitute at Cu (2) sites onCuO2 planes in the lattice, whereas Co and Ga occupy Cu (1) sites along CuO chainsand they have different magnetic moments. Trapped field, levitation force andJc are enhanced due to pinning caused by local suppressed superconducting regions, and theenhancement effects are the highest in the case of Zn doping.