Mod Preparation Of Ybco High Temperature Superconducting Tapes Buffer Layer

Due to its high upper critical magnetic field Hc2(T,J), high critical current density Jc(T,H) (>104A/cm2,1T), low AC loss, the second generation high temperature superconducting(HTS) tapes YBa2Cu3O7-δ(YBCO) became a hotspot of the HTS materials research. As the engineering application requirements, YBCO must be fabricated on flexible metal substrate, And the substrate oxidation, lattice mismatch and relating problems must be overcome simultanously. With depositing buffer layers between the substrate and YBCO layer, these problems can be solved.Among all of the buffer layer preparation metheods, the metalorganic deposition (MOD) method can control the composition precisely without any expensive vacuum system, and has the facility of scalability. In this thesis, CeO2 and La2Zr2O7 buffer layers were deposited on RABiTS Ni-5at%W alloy substrate with MOD method respectlly. The effect on microstructure and surface morphology were studied through the experiments to find out the optimal conditions.The parameters in preparing CeO2 film were studied. Precursor solution was prepared using cerium acetylacetonates as solutes, acetic acid as solvent, water bathing at 60℃for 30min. The precursor solution showed a good stability. In this thesis, 0.1M was used as the concentration of precursor solution. In the spin coating procedure, the spin rate was set at 4000rpm with 30s spinning time. After annealing at 1000℃under Ar+4%H2 reducing atmosphere for 60min, sharp biaxially oriented, homogenous, and crack-free CeO2 film was obtained. The full width at half maximum (FWHM) of omega and phi scan were below 6.0°. The grain size was about 100nm. And the root mean square (RMS) roughness was around 5nm,Another promising candidate buffer layer La2Zr2O7 thin film was also studied. The precursor solution was prepared using zirconium acetylacetonates and lanthanum acetylacetonates as solute disolved in propionic acid. The total cation concentration was 0.8M. The spin rate was 4000rpm. And spin time was 30s. After annealing at 940℃under Ar+4%H2 reducing atmosphere for 30min, sharp biaxially texture, homogenous, and crack-free La2Zr2O7 thin film was obtained. The FWHM of omega and phi scan were 6.0°or so. The grain size was about 100nm. And the RMS roughness was only about 2nm.