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 stabilize d zirconia (YSZ) has been deposited in situ at 600-650 degrees C by la ser ablation. Following the deposition of CeO2, Tl0.78Bi0.22Sr1.6Ba0.4 Ca2Cu3O9 ((Tl,Bi-1223) amorphous films were deposited on the CeO2-buff ered YSZ substrate at room temperature. The deposited amorphous films were then wrapped together with an unfired Tl0.95Bi0.22Sr1.6Ba0.4Ca2Cu 3O9 pellet in silver foil. The whole package was finally annealed ex s itu in a tube furnace at 790-810 degrees C with flowing argon to cryst allize the films. X-ray diffraction (XRD) shows that the annealed film s consist of mainly c-axis aligned (Tl,Bi)-1223 phase with a small amo unt of (Tl,Bi)-1212 phase. The full width at half maximum (FWHM) value s of XRD omega-scans at (007) of (Tl,Bi)-1223 phase and (005) of (Tl,B i)-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 ex cellent in-plane alignment with FWHM values of 0.44 degrees and 0.54 d egrees, respectively. Four-probe transport measurements show supercond ucting transition temperatures (T-c's) of 105-109 K depending on the a nnealing conditions. At 77 K and zero external magnetic field, transpo rt 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.