In-situ High-pressure Transmission Electron Microscopy (TEM) Measurement

地球内部控制着其表面的许多特征和危险。这包括山脉和海洋盆地，以及火山和地震等动力效应。因此，了解地球内部矿物的行为是很重要的。然而，在地球深处产生升高的压力和温度所需的现有实验技术是有限的(例如，极大的钢压机、结合激光加热的钻石顶压机)，这些技术昂贵且难以使用。更重要的是，它们只允许在高压和高温条件下对材料进行有限的检查。相反，必须将产品从设备中取出，才能使用先进的方法进行检查，如电子衍射和使用允许检查结构和反应细节的透射电子显微镜(TEM)的高分辨率成像。事实上，一些在极端条件下形成的材料是不可熄灭的，这意味着当在室温和常压下进行检查时，它们会改变结构，从而改变行为。这个项目旨在通过开发和改进一种在高压和高温下观察材料的方法来解决这个问题，在透射电子显微镜中，我们可以在原子水平上对材料进行检查。它计划利用碳纳米管(CNT)的非凡性能，我们将使用它作为我们希望在高温高压下研究的矿物的容器。最近的研究表明，当高能电子束轰击碳纳米管时，碳纳米管会收缩。因此，它们可以作为可以在透射电子显微镜中研究的微观高压室。因此，这种显微镜的所有优越能力都可以完全移植到原位高压研究中。将得到支持的初步研究将致力于开发将感兴趣的材料放置到微小的碳纳米管中的方法。该团队将从单一元素和简单氧化物和盐等材料开始，以适当地测试和校准这项技术。然后，他们将把这项工作扩展到研究更复杂的矿物，这些矿物被认为丰富地存在于地球内部，并影响或控制地球深部地壳和地幔的行为。Wüstite是一种只在高温下稳定的铁氧化物，以镁辉石的形式大量存在于地球深处，由于它可能在极端条件下不成比例，并对我们星球的历史产生深远影响，因此形成了这项研究的长期重点。总体而言，这些结果将提供有关高压实验技术的基本新知识，这种技术对地球科学以及极端条件下地质和地球物理上重要矿物的性质都是新的。

The interior of Earth controls many features and hazards at its surface. These include mountain ranges and ocean basins as well as dynamic effects like volcanoes and earthquakes. It is thus important to understand the behavior of minerals within Earth's interior. However, the available experimental techniques required to produce the elevated pressures and temperatures that occur deep within Earth are limited (e.g., extremely large steel presses, diamond-anvil cells combined with laser heating) that are costly and difficult to use. More importantly, they allow only limited examination of the materials at high-pressure and -temperature conditions. Instead, the products must be removed from the equipment in order to examine them using advanced methods such as electron diffraction and high-resolution imaging using a transmission electron microscope (TEM) that allows the examination of details of structure and reaction. In fact, some materials that form under extreme conditions are unquenchable, meaning they change structure and thus behavior when examined at room pressure and temperature. This project is designed to solve this problem by developing and refining a way of looking at materials at high pressures and temperatures in place within a TEM, where we can examine them down to the atomic level. It is planned to make use of the remarkable properties of carbon nanotubes (CNTs), which we will use as the containers of the minerals that we wish to study at elevated pressures and temperatures. It was shown recently that CNTs will contract when bombarded with an energetic electron beam. They can thus serve as microscopic high-pressure cells that can be studied within a TEM. Therefore, all the superior capabilities of such microscopy can be fully transplanted to in-situ high-pressure research. The preliminary research to be supported will be devoted to developing methods of placing materials of interest into the tiny CNTs. The team will start with materials such as single elements and simple oxides and salts in order to properly test and calibrate the technique. They will then extend the work to examining more complex minerals that are thought to be abundant in Earth's interior and that influence or control behavior within the deep crust and mantle of the planet. Wüstite, an iron oxide that is only stable at high temperature and is abundant in the deep Earth in the form of magnesiowüstite, forms the long-term focus of this study since it may disproportionate at extreme conditions and have profound effects on the history of our planet. Overall, the results will provide fundamental new knowledge about a high-pressure experimental technique that is new to the earth sciences as well as about the nature of geologically and geophysically important minerals under extreme conditions.