SUPERCONDUCTIVITY AND MICROSTRUCTURAL CHARACTERIZATION OF EPITAXIAL (TL,BI)SR1.6BA0.4CA2CU3O9-DELTA FILMS

An important correlation of 1223 phase development to film thickness h as been found on the films made by laser ablation and post-annealing o n (100) LaAlO3 single crystal substrate. X-ray diffraction (XRD) and t ransmission electron microscopy (TEM) were used to characterize the 12 23 phase development, epitaxy, and microstructure. When the film was t hinner than 0.7 mu m 1212 was the dominating phase, whereas when the f ilm was thicker than 0.9 mu m 1223 was the dominating phase without an y change of the mean composition measured by energy dispersive spectro scopy (EDS). Resistance versus temperature and critical current densit y (J(c)) were measured by the standard four-probe method, The zero-res istance transition temperature (T-c) was 72.4 K for the as-made pure 1 212 film, whereas it was typically 105-111 K for the almost pure 1223 films depending on the 1223 phase purity. The typical J(c) value at 77 K and zero field was 2 x 10(6)A/cm(2) for the 1223 films.