YBCO厚膜的生长机理及超导性能调控研究

YBCO coated conductors exhibit the highest general performance at liquid nitrogen and magnetic field. The study of low-cost chemical solution deposition, the increase of thickness of superconducting layer and the introduction of artificial pinning centers are the key problems of coated conductors for the engineering applications. In this proposal, the YBCO thick layers with artificial pinning centers are prepared by low cost chemical solution deposition. The formation of decomposition defects, the evolution of intermediate phases, the nucleation and growth behaviors of biaxial oriented YBCO thick layer will be investigated. The growth mechanism of YBCO thick layer will be discussed. Different type of pinning center will be introduced into the YBCO thick layer, and the influence of chemical doping on the flux pinning mechanism of YBCO thick layer will be explored. Based on the high Jc-B performance of YBCO thick layer, the effect of growth parameters in reel to reel process on the current capacity of YBCO thick layer will be studied. The consistent biaxial orientation and microstructure, the uniform current capacity of YBCO thick layer parallel to the tapes will be acquired. Meanwhile a theoretical base for the low-cost solution method of coated conductors with high performance will be constructed.

YBCO涂层导体是液氮温区磁场下综合性能最为优异的超导材料，发展低成本的化学溶液沉积技术，增加超导层厚度以及引入人工钉扎中心，是涂层导体实用化面临的关键问题。本项目采用低成本化学法制备YBCO厚膜并引入钉扎中心。通过研究YBCO厚膜的热解缺陷形成、相演变过程、双轴取向形核和生长行为，阐明YBCO厚膜的生长调控机理。通过研究在厚膜中引入不同类型掺杂相，探索化学法掺杂对YBCO厚膜的磁通钉扎性能的调控机制。在获得高Jc-B的YBCO厚膜短样的基础上，研究动态生长环境对YBCO厚膜载流性能的影响规律，解决化学法超导层的取向和微观结构一致性以及在带长方向载流性能的均匀性等问题，为进一步提高化学法涂层导体的性能奠定理论基础。

发展低成本的化学溶液沉积技术，增加超导层厚度以及引入人工钉扎中心，是涂层导体实用化面临的关键问题。本项目采用低成本化学溶液沉积技术制备YBCO厚膜并引入磁通钉扎中心。探索了高质量、良好稳定性的低氟前驱液，优化多次涂敷和热解工艺，解决了厚膜的裂纹和褶皱等宏观缺陷。开发了快速热处理新工艺，抑制超导层的a轴晶和（103）非取向性形核。阐明了双层膜中氟碳变化规律，F元素从上层扩散进入下层，调节下层膜中碳含量，改善了YBCO晶粒的外延取向生长。获得了高性能、优异织构YBCO厚膜的取向生长的调控机理。第二相纳米粒子氧化锆的尺寸和含量对于YBCO的织构取向和Jc具有重要的影响，界面微阵列结合纳米粒子可以显著提高YBCO超导层的磁通钉扎性能。优化动态制备工艺，获得良好织构和超导性能的YBCO涂层导体。研究结果为提高化学溶液沉积制备涂层导体性能奠定理论和实验基础，具有良好的应用前景。