Improvement of critical current density in thallium-based (Tl, Bi)Sr{sub 1.6}Ba{sub 0.4}Ca{sub 2}Cu{sub 3}O{sub 9-{delta}} superconductors

Epitaxial (Tl,Bi)Sr{sub 1.6}Ba{sub 0.4}Ca{sub 2}Cu{sub 3}O{sub x} ((Tl, Bi)-1223) thin films on (100) single crystal LaAlO{sub 3} substrates were synthesized by a two-step procedure. Phase development, microstructure, and relationships between film and substrate were studied by x-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Resistance versus temperature, zero-field-cooled and field-cooled magnetization, and transport critical current density (J{sub c}) were measured. The zero-resistance temperature was 105--111 K. J{sub c} at 77 K and zero field was >2 {times} 10{sup 6} A/cm{sup 2}. The films exhibited good flux pinning properties