低氟MOD法制备YBCO高温超导带材研究

发布时间：2018-03-31 19:38

本文选题：YBCO涂层导体　切入点：低氟MOD法　出处：《电子科技大学》2011年硕士论文

【摘要】：由于YBa2Cu3O7-x(YBCO)涂层导体在性价比以及电学性能等方面具有Bi系高温超导带材所无法比拟的优势,因而在强电领域将有着更加广阔的商业应用前景。在众多制备YBCO涂层导体的方法中,金属有机沉积(MOD)法具有无需真空系统、可精确控制前驱液成分以及便于大面积沉积等优点,是低成本、大规模制备YBCO涂层导体的首选方法。本论文基于低氟MOD法在沉积有Y_2O_3/YSZ/CeO_2 (YYC)缓冲层的金属基带表面开展了YBCO超导薄膜制备工艺的研究。采用环烷酸铜取代三氟乙酸铜制备了低氟含量的前驱液,通过研究前驱液溶质在多种常用溶剂中的溶解情况确定了合适的溶剂,同时研究所得前驱液的稳定性发现采用四氢呋喃作溶剂制备的前驱液在室温下、纯氮气环境中可稳定保存30天。随后系统地研究了低氟MOD法低温热处理过程中升温速率对前驱膜表面形貌以及YBCO薄膜微观结构和表面形貌的影响。另外开展了低氟MOD法高温热处理工艺对YBCO薄膜的影响研究,通过优化各种工艺参数(处理温度、氧分压以及单层膜厚度),在较优的工艺参数下得到纯c轴取向、面内外半高宽分别为4.6°和1.4°的YBCO超导薄膜,在77K、自场条件下测得其临界电流密度以及临界电流分别为0.4MA/cm2和40A/cm-width。同时在低氟MOD法制备YBCO薄膜过程中发现,BaCeO_3的形成与缓冲层中CeO_2的表面形貌有关,CeO_2的表面晶粒大小和表面均方根粗糙度较大都会导致大量的BaCeO_3生成,从而影响YBCO薄膜的外延生长;通过在高温热处理结束时添加高温氧化退火过程,可大幅减少YBCO薄膜中YBa_2Cu_4_O8(Y124)相缺陷的含量。
[Abstract]:Because YBA _ 2Cu _ 3O _ 7-x YBCO) coated conductors have more advantages than Bi-based HTS tapes in cost performance and electrical properties, YBA _ 2Cu _ 3O _ (7-x) coated conductors will have a wider commercial application prospect in the field of strong electricity. The metal-organic deposition (MOD) method has the advantages of no vacuum system, accurate control of precursor composition and convenience for large area deposition. In this thesis, the preparation of YBCO superconducting thin films on the surface of metal substrate deposited with Y_2O_3/YSZ/CeO_2 YYC buffer layer has been carried out based on the low fluorine MOD method. The precursor solution with low fluorine content was prepared by replacing copper naphthenate with copper trifluoroacetate. The suitable solvent was determined by studying the dissolution of solute in various common solvents. At the same time, the stability of the precursor was studied. It was found that the precursor prepared by using tetrahydrofuran as solvent was prepared at room temperature. The effect of heating rate on the surface morphology of precursor film, microstructure and surface morphology of YBCO film during low temperature heat treatment by low fluorine MOD method was systematically studied. In addition, the effect of high temperature heat treatment of low fluorine MOD process on YBCO thin films was studied. By optimizing various process parameters (treatment temperature, oxygen partial pressure and thickness of monolayer films), the pure c-axis orientation was obtained under better technological parameters. The YBCO superconducting thin films with in and out of plane half-width of 4.6 掳and 1.4 掳, respectively, At 77K, the critical current density and critical current were determined to be 0.4MA/cm2 and 40A / cm-width. meanwhile, it was found that the formation of BaCeO3 was related to the surface morphology of CeO_2 in buffer layer during the preparation of YBCO thin films by low-fluorine MOD method. And the larger root-mean-square roughness of the surface leads to a large amount of BaCeO_3 generation, By adding high temperature oxidation annealing process at the end of high temperature heat treatment, the content of YBA _ 2Cu _ 4O _ (8) O _ (124) phase defects in YBCO thin films can be greatly reduced.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TM26

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