Mechanical Damage of YBa2CU3O7-Coated Conducting Film Caused by Its CeO2 Interface with Defects

YBa2Cu3O7 (YBCO) multilayer coating conductors are the second generation superconductor wires. The interface structure plays an important role in the performance of the material, especially that between the superconducting layer and the CeO2 buffer layer. The YBCO/CeO2 interface is not only very critical on the atomic scale for effectively modulating the polycrystalline structure of YBCO, but also, as weak connection on the macro level, profoundly affect macro physical properties of the whole film, for example, mechanical toughness. Generally, most defects at the YBCO/CeO2 interface are generated during the fabrication, and further develop when the film is wound or in the process of current carrying. These defects, at different level, lead to mechanical damage even under simple deformations such as tension and bending. In this work, by way of atomistic computer simulations with the molecular dynamics (MD), a two-dimensional YBCO/CeO2 interface atomic model was developed and validated. On this interface model, the damage propagation on the atomic-scale and further analysis with stress and potential energy especially affected by the YBCO/CeO2 interface with/without defects under the tension and bending have been comprehensively investigated. As a result, we not only visualized the simulated damage process and route on the YBCO/CeO2 interface, but also more importantly, combined with the variation of macro properties, deeply analyzed the damage mechanism caused by the interface and its defects.