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

原位高压透射电子显微镜 (TEM) 测量

• 批准号: 0948535
• 负责人: Peter Buseck
• 金额: $ 30.02万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0948535&HistoricalAwards=false
• 关键词: situ; pressure; Transmission; Electron; Microscopy

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.

地球内部控制着其表面的许多特征和危险，其中包括山脉和海洋盆地以及火山和地震等动态影响，因此了解地球内部矿物的行为非常重要。产生地球深处的高压和高温所需的设备是有限的（例如，非常大的钢压机、金刚石砧室与激光加热相结合），这些设备成本高昂且难以使用，更重要的是，它们只能进行有限的检查。材料在相反，必须将产品从设备中取出，以便使用电子衍射和使用透射电子显微镜 (TEM) 的高分辨率成像等先进方法来检查它们，从而可以检查产品的细节。事实上，一些在极端条件下形成的材料是不可淬灭的，这意味着它们在室温和压力下检查时会改变结构，从而改变行为。该项目旨在通过开发和改进一种观察材料的方法来解决这个问题。在高压和高温下放置在 TEM 中，我们可以在原子水平上对其进行检查，计划利用碳纳米管 (CNT) 的卓越特性，我们将使用碳纳米管作为我们希望在高温下研究的矿物的容器。最近的研究表明，碳纳米管在受到高能电子束轰击时会收缩，因此可以作为可在 TEM 中进行研究的微观高压电池。移植到原位高压研究中，该团队将从单元素、简单氧化物和盐等材料开始，致力于开发将感兴趣的材料放入微小碳纳米管中的方法。然后，他们将把工作扩展到检查更复杂的矿物，这些矿物被认为在地球内部丰富，并影响或控制地球深层地壳和地幔的行为，这是一种铁氧化物。仅在高温下稳定，并且以镁方石的形式存在于地球深处，构成了这项研究的长期焦点，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的影响。提供有关地球科学新技术的高压实验技术以及极端条件下地质和地球物理重要矿物性质的基本新知识。