Phase Formation and Grain Growth Kinetics of High-Tc Superconducting Tl-1223 Ceramics

The phase formation and grain growth of (Tl,Pb,Bi)(Sr,Ba)₂Ca₂Cu₃O_9– ceramics were investigated in the temperature range between 860°C and 1000°C. It was found that partial melting seems to improve the texture of the samples. The phase purity, however, is limited due to an incomplete re-precipitation process due to the formation of a liquid phase, which is already present above 885°C. The resulting grain growth exponent n, however, appears to differ from the classical exponent of 1/3 for the coexistence of a liquid phase in the temperature range between 885°C and 920°C. For the first time, the activation energy for the high-T_c Tl-1223 phase has been determined showing faster grain growth kinetics than for Y-123 and Bi-2223.