Fabrication of artifical heterostructures with possible oxygen ion conductions

我们探索了包括褐铁矿在内的人工异质结构的结构和输运性质。这将为进一步开发新型氧离子导体提供宝贵的基础见解。在本项目中，我们首先发现了缺氧铁基氧化物外延薄膜中的高温金属-绝缘体转变。这与块体的行为不同，对于铁基氧化物来说，金属-绝缘体的转变温度最高为620K。我们还建立了一种在原子水平上使用环状亮场成像来澄清像差校正扫描透射电子显微镜(STEM)中的扭曲的方法。通过这种方法，我们发现在应变的薄膜中氧原子的位置存在一定的自由度，我们进一步制备了由褐铁矿和钙钛矿组成的异质结构，并发现由于界面上没有氧空位有序化而产生了新颖的导电行为。

We explore structural and transport properties of artificial heterostructures including brownmillerite. This would provide invaluable fundamental insight for further development in creating novel oxygen ion conductors. In this project, First we discover high-temperature metal-insulator transition in oxygen-deficient Fe-based oxide epitaxial thin films. This is distinct from the behavior for the bulk and the metal-insulator transition temperature of 620K is highest for the Fe-based oxide.We also established that an approach to clarify distortions at an atomic level using annular bright-field imaging in aberration-corrected scanning transmission electron microscopy (STEM). With this approach, we revealed that in a strained film there are some degrees of freedom of the oxygen atomic positions.We further fabricate heterostructure consisting of brownmillerite and perovskite and found the novel conducting behavior due to the absence of the oxygen vacancy ordering at the interface.