Liquid Source Metal-organic Chemical Vapor Preparation Of Ybco High Temperature Superconducting Thin Films

High-temperature superconductor (HTSC) material YBa2Cu3O7-δhas extensive applications in superconductor generator, electromotor, current limiter, energy storing system. It is extreme hard to deposit coated conductor on flexible metal taps of Ni. The problems of fast fabrication, lattice mismatch, and diffusion of oxygen have to be solved.In this dissertation, the fabrication of YBCO on single crystal LAO and rolling-assisted biaxially textured substrates (RABiTS) with Metal organic chemical vapor deposition method was studied. A MOCVD system was designed and produced to study the process parameters of growing YBCO layer on LAO, and then, the subsequent growth of YBCO coated conductors was also investigated.A liquid deliver system was designed to deliver and vaporize the metal organic solution. Capillary with micro holes was use to mix the deliver gas and metal organic solution and make sure the solution is continuously and stably delivered. The system lays the foundation for industrial production research. Different chamber vent systems were designed to do comparative experiments. The flow control system of MOCVD was improved, which makes the flow above the substrate slower. Fully c-axis YBCO layer was produced on LAO. The critical current is 0.2MA/cm2.A systematic study of the growth conditions for growing YBCO layer on LaAlO3 single crystal was performed. The parameters of temperature, total pressure, and O2 partial pressure were examined. With optimum processing parameters, full c-axis YBCO layer was obtained. The FWHM value of (005) peak is 0.4°, and the critical current is 0.6 MA/cm2.YBCO coated conductor is deposited on Ni-5%W/Y2O3/YSZ/CeO2 resulting in highly textured YBCO with out-of-plane FWHM value of 3.5°when the CeO2 layer has out-of-plane FWHM value of 5.5°. In addition, fully c-axis YBCO layer with out-of-plane FWHM value of 3.5°is obtained at 865℃.