功能氧化物异质界面结构的亚埃尺度研究

项目名称： 功能氧化物异质界面结构的亚埃尺度研究

项目编号： No.51471169

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 一般工业技术

项目作者： 米少波

作者单位： 西安交通大学

项目金额： 80万元

中文摘要： 由钙钛矿结构的氧化物组成的异质界面对材料的物理性能有非常重要的影响。由于界面耦合效应在异质界面区域不但可能会有新物相的产生，而且可能会有奇特物理现象的出现（如超导特性、磁性、金属-绝缘体转变）。然而，目前的常规实验分析方法（如同步辐射X射线衍射）不能在原子尺度上描述复杂异质结构的界面结构和考察理论计算中使用的界面原子模型的有效性。 本项目拟利用像差校正电子显微术中的负球差成像技术和高角环形暗场像技术等手段对BiFeO3多铁氧化物和(Ba,Sr)(Ti,Zr)O3铁电氧化物外延生长在不同衬底上的异质结构的界面进行系统研究。在亚埃尺度研究异质结构体系中界面的原子构型和界面应变等科学问题。项目的完成不仅将有助于在原子尺度揭示异质结构的界面耦合机制，而且将较深入地认识界面对多铁性氧化物薄膜中的畴结构，以及对铁电氧化物薄膜的界面尺寸效应的影响。同时，有助于理解异质界面结构与物理特性的内在联系。

中文关键词： 高分辨电子显微学；界面结构；薄膜；钙钛矿氧化物；界面耦合

英文摘要： Physical properties of heterostructures are strongly affected by the interface between perovskite oxides. The occurrence of interface coupling in the heterostructures through controlled synthetic routes could lead to not only new phases, but also novel properties, including superconductivity, magnetism, metal-insulator transition. Nevertheless, the interface structure determined by conventional methods (e.g., synchrotron x-ray diffraction) could not uniquely define the interface structure at the atomic scale and validate the structure model used in theoretical calculations concerning the complex of heterointerface. In this work, by means of high-resolution negative spherical aberration (Cs) imaging technique and high-resolution high-angle annular dark-field imaging in aberration-corrected ultra-high resolution electron microscopes, interfaces of heterostructures of BiFeO3 ferroic and (Ba,Sr)(Ti,Zr)O3 ferroelectric oxides epitaxially grown on various substrates (e.g., SrTiO3, LaAlO3 and NdGaO3) will be studied systematically. Interface structure, strain relaxation and interfacial diffusion in the functional oxide heterostructures will be characterized at the sub-Angstrom resolution level. The finding in this work will be helpful not only to explore the mechanism of interface coupling at the atomic scale, but also to build the relation between the interface structure and the novel properties of the heterostructures. In addition, the finding in this work will be helpful to understand the effect of heterointerfaces on the formation of domain within BiFeO3 thin films, and finite size effect in (Ba,Sr)(Ti,Zr)O3 thin films.

英文关键词： High-resolution electron microscopy;Interface structure;Thin film;Perovskite oxides;Interface coupling