Enhanced Superconductivity in the Tl 1−X Bi X Ba 2 Ca 2 Cu 3 O y System

Compounds of the system, Tl 1−x Bi x Ba 2 Ca 2 Cu 3 O 9 , were synthesized and studied. Bi substitutes at the Tl-site for values of x up to x=0.2. The superconducting transition temperature, T c , increases from 110K for x=0.0 to 116K for x=0.2. SEM images reveal a plate-like morphology which is highly suitable for powder-in-tube processing. M-H loops show that the Bi-substituted phase has significantly better low temperature flux pinning properties than the pristine Tl-cuprate, and exhibits only a weak dependence on temperature and field when compared to that of unsubstituted phase. The J c values calculated using the Bean model are: 3 × 10 7 A/cm 2 at 10K,1T and 2 × 10 4 A/cm 2 at 77K.1T. Substitution of 20% of Bi in TlBa 2 Ca 2 Cu 3 O 9 makes the compound an excellent choice for magnet wire applications at relatively low temperatures.