An improved technique for the growth of (Tl_0.95Bi_0.2)(Sr_0.8Ba_0.2)₂Ca₂Cu₃O_x superconducting thin films in oxygen and argon

We fabricated (Tl0.95Bi0.2)(Sr0.8Ba0.2)(2)Ca2Cu3Ox (Tl, Bi-1223) superconducting thin films on a LaAlO3(001) substrate by a three-step process including magnetron sputtering and two post-annealing processes. In the post-annealing process we found that the (Tl0.95Bi0.2)(Sr0.8Ba0.2)(2)Ca-1 Cu2Ox (Tl, Bi-1212) phase formation played a very important role in obtaining the Tl, Bi-1223 superconducting phase. So, the precursors were annealed at lower temperature to form the Tl, Bi-1212 phase entirely, and then almost pure Tl, Bi-1223 phase superconducting thin films could be obtained by annealing the Tl, Bi-1212 film at higher temperature. The superconducting critical temperature T-c of the Tl, Bi-1223 film annealed in oxygen and in argon was 111 K and 107 K, respectively. The critical current density J(c) (77 K, 0 T) of the Tl, Bi-1223 film annealed in oxygen was as high as 3.7 MA cm(-2).