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。这些因素包括山脉和海洋盆地，以及火山和地震等动态效应。因此，了解地球内部矿物的行为非常重要。然而，产生发生在地球深处的升高的压力和温度所需的可用实验技术是有限的（例如，非常大的钢压机、与激光加热相结合的金刚石砧单元），这些设备昂贵且难以使用。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，产品必须从设备中取出，以便使用先进的方法进行检查，例如电子衍射和使用透射电子显微镜（TEM）的高分辨率成像，可以检查结构和反应的细节。事实上，一些在极端条件下形成的材料是不可淬火的，这意味着它们在室温和室温下检查时会改变结构和行为。该项目旨在通过开发和改进一种在TEM中在高压和高温下观察材料的方法来解决这个问题，在那里我们可以将它们检查到原子水平。计划利用碳纳米管（CNT）的显着特性，我们将使用它作为我们希望在高压和高温下研究的矿物的容器。最近的研究表明，当用高能电子束轰击碳纳米管时，碳纳米管会收缩。因此，它们可以作为微观高压细胞，可以在TEM中进行研究。因此，这种显微镜的所有上级功能都可以完全移植到原位高压研究中。支持的初步研究将致力于开发将感兴趣的材料放入微小CNT中的方法。该团队将从单一元素和简单的氧化物和盐等材料开始，以便正确测试和校准该技术。然后，他们将把这项工作扩展到研究更复杂的矿物，这些矿物被认为在地球内部丰富，并影响或控制地球深部地壳和地幔的行为。菱铁矿是一种氧化铁，仅在高温下稳定，以镁菱铁矿的形式大量存在于地球深处，是本研究的长期重点，因为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。总的来说，这些结果将提供有关地球科学新的高压实验技术以及极端条件下地质和矿物重要性的基本新知识。

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.