In-plane aligned superconducting Tl_0.78 Bi_0.22 Sr_1.6 Ba_0.4 Ca₂ Cu₃ O₉ films on rolling assisted biaxially textured substrates

In-plane aligned superconducting Tl_0.78 Bi_0.22 Sr_1.6 Ba_0.4 Ca₂ Cu₃ O₉ ((Tl,Bi)-1223) films on Rolling Assisted Biaxially Textured Substrates (RABiTS) with J_c of 4.25 × 10⁵ A/cm² at 77 K and zero-field have been synthesized by laser ablation and post-ablation annealing. The as-ablated films were amorphous due to the low substrate temperature during ablation. The amorphous films were then wrapped together with an unfired Tl_0.95 Bi_0.22 Sr_1.6 Ba_0.4 Ca₂ Cu₃ O₉ pellet in silver foil. The whole package was finally annealed in a tube furnace at 780-810°C for 40-60 min in flowing argon to crystallize the films. X-ray diffraction (XRD) shows that the annealed films consist of mainly c-axis aligned (Tl,Bi)-1223 phase with a small amount of (Tl,Bi)-1212 phase. The full width at half maximum (FWHM) values of XRD peaks show that both phases are epitaxial, with in-plane and out-of-plane alignments comparable to those of the underlying Ni and buffer layers (CeO₂ and YSZ). Four-probe transport measurements showed superconducting transition temperatures (T_cs) of 105-109 K depending on the annealing conditions. With external magnetic field applied parallel to the c-axis, irreversibility magnetic fields reached beyond 3 T at 77 K and beyond 5 T at 64 K.