Growth and characterization of superconducting films Tl0.78Bi0.22Sr1.6Ba0.4Ca2Cu3O9 on CeO2-buffered single crystal YSZ

Crystalline CeO2 as a buffer layer on single crystal yttrium stabilized zirconia (YSZ) has been deposited in situ at 600-650 degrees C by laser ablation. Following the deposition of CeO2, Tl0.78Bi0.22Sr1.6Ba0.4Ca2Cu3O9 ((Tl,Bi-1223) amorphous films were deposited on the CeO2-buffered YSZ substrate at room temperature. The deposited amorphous films were then wrapped together with an unfired Tl0.95Bi0.22Sr1.6Ba0.4Ca2Cu3O9 pellet in silver foil. The whole package was finally annealed ex situ in a tube furnace at 790-810 degrees C with 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 omega-scans at (007) of (Tl,Bi)-1223 phase and (005) of (Tl,Bi)-1212 phase are 0.44 degrees and 0.48 degrees respectively. XRD phi-scans on (102) of both (Tl,Bi)-1223 and (Tl,Bi)-1212 phases show an excellent in-plane alignment with FWHM values of 0.44 degrees and 0.54 degrees, respectively. Four-probe transport measurements show superconducting transition temperatures (T-c's) of 105-109 K depending on the annealing conditions. At 77 K and zero external magnetic field, transport critical current density (J(c)) is in the range of (0.6-1) x 10(6) A/cm(2) for samples with thickness of 1.5-1.8 mu m. (C) 1998 Elsevier Science B.V. All rights reserved.