2-ZONE ANNEALING OF TL0.5PB0.5(SR0.8BA0.2)(2)CA2CU3OY

Stable conditions have been identified for two-zone processing of the superconducting thallium cuprate Tl0.5Pb0.5(Sr0.8Ba0.2)(2)Ca2Cu3Oy. Wi th P(O-2) of 0.8 atm, P(Tl2O) of 4.4 X 10(-3) atm, and a sample temper ature of 920 degrees C, single-phase Tl0.5Pb0.5(Sr0.8Ba0.2)(2)Ca2Cu3Oy is produced with a T-c of 115 K, complete diamagnetic shielding, and Meissner fraction greater than 70%. Although a small amount of melting occurs under these conditions, a comparison of the low-field diamagne tic shielding for these samples with samples of Pb- and Sr-free TlBa2C a2Cu3Oy and Tl2Ba2Ca2Cu3Oy suggests that such melting is not necessary to produce the triple-CuO2-layer superconductors.