INFLUENCE OF Y2BACUO5 PARTICLES ON THE GROWTH-MORPHOLOGY OF PERITECTICALLY SOLIDIFIED YBA2CU3O7-X

Modifications of a recent model by Izumi et al.1 on diffusion controll ed growth of YBa2Cu3O7-x (123) superconductors are proposed, taking in to account especially the engulfment process of the Y2BaCuO5 (211) par ticles into the solidifying 123 interface. The proposed modifications are evidenced by experimental results and applied to explain microstru ctural features of the 123 superconducting material. In particular, th e 1:1 correlation between 123 platelet thickness (planar defect spacin g) and 211 particle size as described by Jin et al.2 is explained by a n observed bridge growth resulting in a zipper-like mechanism. By this mechanism the platelets grow together in an oriented way leading to a quasi single crystalline material.