Microstructural Study of the Y-Ba-Cu-O System at High Temperatures

Abstract

Phase relations for the Y-Ba-Cu-O system near 1:2:3 stoichiometric compositions at high temperatures have been studied through microstructural observation. It has been found that YBa 2 Cu 3 O x decomposes into a Y 2 BaCuO 5 (211) plus liquid (a mixture of BaCuO 2 and CuO) phase at around 1050°C and the 211 phase further decomposes into Y 2 O 3 plus liquid at around 1200°C. Even at 1500°C Y 2 O 3 seems to be stable. On cooling Y 2 O 3 reacts with the liquid to produce the 211 phase by peritectic solidification. At around 1000°C the 211 phase reacts with the liquid to produce the YBa 2 Cu 3 O x phase again by the peritectic reaction.