The Investigation Of Anneal Process And Slight Element Doping At Cu Site In YBCO Superconducting Thin Film

In this thesis, the anneal process of using a fluorite-free MOD method to synthesize YBa2Cu3O7-x (YBCO) superconducting thin film was optimized, then slight element doping at Cu site in YBCO thin film was investigated.After analysis of extensive literature about the YBCO superconducting thin film, the anneal process of using a fluorite-free MOD method to synthesize YBCO thin film was investigated. The reasearch results about the low temperature heat treatment decomposition process show that the best heating rate is 0.5℃/min in low temperature decomposition process and too fast or too slow heating rate is not conducive to the late epitaxial growth of thin film.Then in the case of the other parameters constant, this thesis explored the connection between atmosphere humidity of high-temperature heat treatment process and microstructure and superconductivity of the film, experiments show that humid atmosphere during high-temperature heat treatment process was not propitious for epitaxial growth of YBCO films. This optimized heat treatment process not only can further improve the microstructure the film,but also improved properties resulted in a great promotion of YBCO films,which has the Jc(77K,0T) up to 2.19MA/cm2.The effect of slight Zn and Ni element doping at Cu site (nominal doped level was 0.0005,0.001,0.002 and 0.004) doping on critical current densities of YBCO films in high magnetic field was also investigated. YBCO films with slight Zn and Ni element doping have been synthesized by using the optimized fluorite-free MOD method, then microstructures and and the critical current density (Jc) of YBCO films have been investigated by x-ray diffraction,scanning electron microscopy and mpms method. Research results show that YBCO films with slight Zn and Ni element doping displays smooth and dense surface morphology, while Tc decreases with the increase of doping. The inhibitory effect of Zn element doping on Tc is slightly stronger than Ni element doping.The effect on superconductivity of slight Zn element doping was stronger than slight Ni element doping.The pinning center by slight Zn and Ni element doping can distinctly enhance the Jc value of YBCO films.