ENTRAPMENT OF BA-CU-O LIQUID-PHASE DURING GROWTH OF A Y1BA2CU3O(7-Y) DOMAIN

Entrapment of Ba-Cu-O liquid phase during the growth of a 123 domain was investigated in the melt-textured Y-Ba-Cu-O oxide. From the microstructural examination of the growth front of the 123 domain, it is found that liquid phase is entrapped in the channels between adjacent 123 platelets formed ahead of the 123 domain, owing to the anisotropic growth of the 123 platelet, the difference between the growth rate of the 123 platelet and the dissolution rate of 21 1 in the liquid phase, and the inhomogeneous distribution of 211 particles at the peritectic reaction front. Dissolution of 211 particles in the reaction region, which supplies an yttrium source to the liquid channels, allows the entrapped liquid phase to solidify to 123 phase. After the peritectic reaction, the liquid channels tum into plate boundaries containing residual liquid phase as evidence of the entrapment. Isolation of the entrapped liquid phase from the yttrium source (211 particles) by the solidified 123 phase appears to be responsible for the presence of the residual liquid phase.