Mocvd Process Deposition Of Ybco Superconducting Layer Experimental Study

The second-generation yttrium barium cuprite ( YBCO ) high temperature superconductor tape attracts general concern by the market because of its good high-temperature properties in the liquid nitrogen temperature, the potential of low production cost and low AC loss. It has a wide range of applications such as superconducting generators, cables, motors and superconducting magnetic energy storage. Among many deposition processes of superconducting layer, metal organic chemical vapor deposition (MOCVD) process can achieve continuous, rapid, uniform deposition on the long flexible metal substrate, which makes it of great production value.In this thesis, with self-made MOCVD system, YBCO thin films were deposited on short CeO₂/YSZ/Y₂O₃/NiW substrates for later experimental research of continuous production of YBCO coated conductors. The content of this thesis can be concluded as follows:1. Improving self-made MOCVD system. A liquid deliver system of MOCVD was designed, which reduced the probility of clogging, to help metal organic precursor enter evaporation chamber in the form of fog and facilitate the flash evaporation. At the same time the bottom of heater in the evaporation chamber was changed into rotating copper plate to periodically clean off the evaporation residues of metal organic source, and the evaporation effect was enhanced. In addition, with Computational Fluid Dynamics software, the temperature field and the flow field were simulated to obtain optimized parameters for modifying the deposition system.2. Modifying the preparation method of metal organic source.The purity and quality of metal organic source is one of the most critical factors that impact the deposition of YBCO film. By improving the preparation process, adding purification process, introducing the assistant ligand, a set of practical preparation methods of MO sources was achieved and stabilized, which meet the demand of experiment and provide a raw material guarantee for the smooth progress of the study. 3. Optimizing the process parameters of the preparation of YBCO films. CeO₂/YSZ/Y₂O₃ was picked up as buffer layer between the YBCO thin films and NiW substrate. By adjusting the conditions such as temperature, oxygen partial pressure, metal organic source ratio, the impact of each individual process parameter was studied, the complete c-axis oriented YBCO epitaxial thin films were successfully prepared and good experimental repeatability was obtained.