涂层导体中缓冲层的织构传递与阻隔扩散机制

项目名称： 涂层导体中缓冲层的织构传递与阻隔扩散机制

项目编号： No.50872115

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 卢亚锋

作者单位： 西北有色金属研究院

项目金额： 28万元

中文摘要： 涂层导体是实现氧化物高温超导材料在液氮温区应用的关键材料，它是由金属基带/缓冲层/超导层/保护层组成的多层复合材料。由于金属基带与超导层之间存在较大的晶格失配（约8%）和严重的扩散，因此必须在二者之间沉积复杂的氧化物缓冲层，才能达到织构传递和阻隔扩散的效果，最终实现氧化物超导层的双轴织构生长和高载流能力。目前缓冲层结构仍处在不断发展之中，其重要原因是缓冲层织构传递和阻隔扩散机制不清楚。本项目在研究金属基带上氧化物薄膜的结构稳定性基础上，从晶格失配和界面结构出发，研究了缓冲层中织构的形成和传递机制，并揭示缓冲层的阻隔扩散机制，采用新型前驱液制备了Ni-W基带上高度织构且无微裂纹的La3TaO7和SrTiO3薄膜，还研究了影响CeO2薄膜表面裂纹形成的影响因素，在此基础上探索了多功能双钙钛矿氧化物作为单层缓冲层的可能性。本项目的研究为涂层导体缓冲层材料的选择以及超导层制备工艺的优化提供理论支持，也为理解涂层导体缓冲层功能并优化缓冲层结构提供指导，同时对于认识异质外延过程的机理、发展金属衬底上功能氧化物也具有重要的学术价值。

中文关键词： 高温超导材料；涂层导体；缓冲层；织构；扩散

英文摘要： Coated conductors, which are multi-layer composite materials composed of metal substrate/buffer layer/superconducting layer/protective layer, become the key materials to realize their high magnetic field applications at 77K. There exists a large lattice mismatch of about 8% between YBCO and metal substrate and serious atom diffusion. Therefore, it is necessary to deposite the complicated oxide buffer layers between the metal substrate and the superconducting layer to prevent diffusion of oxygen and Ni atoms during high-temperature processing and to transfer the biaxial texture of the metal substrate into the superconducting layer, finally to realize the bi-axial texture growth and to obtain high carrying current ability of the superconducting layer. At present, the architecture of buffer layer is in the process of the incessant development because the texture transfer and the prevention diffusion mechanism of buffer layer are not still clear. The texture formation and transfer mechanism of buffer layer have been studied and the prevention diffusion mechanism of buffer layer has been cleared in this project in aspect of the lattice mismatch and interface structure based on the investigation of structral stablity of oxide film on metal substrate. The highly textured La3TaO7 and SrTiO3 buffer layers with crack-free surface morphology have been obtained on Ni-W subsrtaes by CSD methods using the new precursor solution routes. The factors influencing the formation of cracks on the surface of CeO2 film on Ni-W substrate has been explored. Then we explored the possibility of using multi-functional double perovskite oxide as single buffer layer. The research of this project provides the theoretic support for the choice of buffer layer materials in coated conductors and the optimization of preparation schedule of superconducting layer, it also supplies the guide for understanding the function of buffer layer and optimizing the architecture of buffer layer in coated conductors. Moreover, it has the important academic value to realize the heterogenous epitaxial mechanism and develop the functional oxide on metal substrate.

英文关键词： high-temperature superconductivity materials; coated conductors; buffer layer; texture; diffusion