STUDY OF GROWTH-KINETICS IN MELT-TEXTURED YBA2CU3O7-X

Directional solidification has been shown to be a successful way of ac hieving high current densities in bulk YBCO. The lack of understanding of the growth kinetics, however, makes it difficult to fabricate long er samples and reduce the processing times. To study the growth kineti cs, quenching experiments of undoped YBa2Cu3O7-x (Y-123) and Y-123 dop ed with Pt and Nd from above the peritectic temperature with different holding times, t, were conducted. The results of these experiments in dicate that the average 211 particle size varies at t(1/3). Growth rat e experiments were also conducted on these samples to determine the ma ximum growth rate for plane front solidification, R(max). This quantit y was measured for undoped and doped Y-123, and it was found that the addition of Pt did not increase R(max) while the addition of Nd double d the growth rate. Using the coarsening results together with the grow th rate experiments, the diffusivity of Y in liquid and the 211-liquid interfacial energy for undoped and doped Y-123 were calculated.