Preparation of the single phase LaBa2Cu3Oy superconductor with T-c(0) 97 Kand suppression of the substitution of La for Ba

The effect of processing conditions on phase formation, solid solution rang e and superconductivity for die La1+zBa2-zCu3Oy system was investigated sys tematically again to obtain and understand the optimum preparation conditio n of La-123 superconductors. The results indicate that (1) the solid soluti on ranges are z=0.20-0.70 and z=0 for La1+zBa2-zCu3Oy sintered and cooled i n air and in N-2, respectively. (2) In LaBa2Cu3Oy, La can substitute for Ba , but Ba cannot substitute for La. This substitution is suppressed when LaB a2Cu3Oy was sintered and cooled in N-2. (3) A single phase LaBa2Cu3Oy super conductor with the highest T-c of 97 K was obtained for the first time when the sample is sintered at 900 degrees C for 40 h in N2 and cooled down to 305 degrees C in N-2 then treated in dried flowing O-2 for 40-60 h. (C) 199 9 Elsevier Science S.A. All rights reserved.