Insight into the Interfacial Nucleation and Competitive Growth of YBa2Cu3O7−δ Films as High-Performance Coated Conductors by Fluorine-Free Metal-Organic Decomposition Route

Fluorine-free metal-organic decomposition route (FF-MOD) is one of the table-top method for the growth of high quality superconducting YBa2Cu3O7−δ (YBCO) films due to its advantages of being environment friendly and faster films deposition rate. However, the nucleation and growth mechanism originated during this process are not yet comprehensively understood. In this paper, microstructural characteristics of the YBCO films quenched from different growth stages were investigated, based on which a complete nucleation and growth model is established. Micro-Raman and scanning electron microscope (SEM) coordinated study demonstrates the coexistence of polycrystalline and epitaxial grains at early stage of nucleation. Combined analysis of transmission electron microscopy (TEM) and secondary ion mass spectroscopy (SIMS) indicate that YBCO epitaxial nucleates by following the Volmer-Weber growth mode. We observed that as the growth process proceeds, the nuclei at the interface have significant growth advantage ov...