Transient liquid assisted nucleation mechanism of YBa₂Cu₃O_7-δ in coated conductor films derived by BaF₂ process

It is significant for low-cost preparation of YBa₂Cu₃O_7-δ (YBCO) coated conductors to make clear the mechanism of orientation, copper segregation, and nucleation density in BaF₂-derived YBCO crystallization. In the present work, a distinct nucleation mechanism was proposed based on a transient liquid phase induced by the size effect as well as near-equilibrium assumption. With this scheme the nucleation of YBCO prepared by metal-organic deposition (MOD) or the physical vapor deposition BaF₂ process was semi-quantitatively analyzed, revealing that the direct driving force for nucleation is YBCO supersaturation in the liquid phase. The theoretical analysis on the nucleation orientation portion is evidenced by the experimental result.