MRI: Acquisition of an Aberration Corrected High Resolution Analytical Transmission Electron Micro. for Advanced Materials Research

技术文摘。该显微镜旨在通过原子分辨率确定固体中原子的空间排列及其化学/键合，从而进一步了解独特新材料的结构/性质关系。该显微镜的工作功率高达300 keV，配有单色场发射电子源，探头形成透镜的C3/C5球差校正器，高分辨率电子能量损失光谱仪，高计数率能量色散x射线光谱仪，以及非常稳定的高倾斜范围台，用于断层扫描和常规成像。目前该显微镜的版本在环形暗场和明场STEM中显示了0.5 Å的图像空间分辨率，在电子能量损失光谱中显示了110 meV的能量分辨率。所有用于这些模式的探测器都是数字的，这有利于纳米结构的定量测量和教学。这种显著的空间/能量分辨率足以定量研究原子/化学分布在最重要的性质上——确定固体的结构特征，如异相界面和晶界，以及催化剂表面。此外，像差校正器可以使用从枪的大电子收集角度，形成非常小的，也非常高电流的电子探针。高电流探针能够在相对较短的时间内收集许多图像、电子能量损失和x射线光谱，以非常高的分辨率得出固体的二维化学图。稳定的高倾斜阶段使我们能够使用层析成像将映射扩展到三维，这是一种相对较新的材料科学研究成像方法，我们将对其进行彻底探索，以确定其局限性。这台显微镜将被安装在LeRoy Eyring固态科学中心，一个多用户设施，在材料学院。它将为外部大学和工业实验室研究人员提供前沿材料研究。摘要所有材料的工程特性，如结构航空航天合金和用于计算机和手机的电子材料微芯片，都取决于构成材料的原子的几何排列和化学特性。这些关系叫做？性质结构关系?对于所有类型的材料，它们是材料科学与工程领域的重要组成部分。显微镜在材料科学和工程中的作用是确定这种关系中的材料结构。电子显微镜，特别是高分辨率的分析透射电子显微镜，是我们确定这种关系的结构部分的最高分辨率的方法。本项目所获得的显微镜正是电子显微镜技术的前沿，将从新的先进材料中产生许多新的和令人兴奋的结果，以提高我国在纳米技术方面的竞争地位，并将为我国大学生提供纳米材料表征的必要教育。该显微镜将在图像中实现0.5 Ångstrom（0.00000001厘米，或小于1个原子直径）的空间分辨率，在纳米光谱中实现约0.001电子伏特（1 meV）的能量分辨率，从而在原子尺度上确定材料中的化学键。这台显微镜的特殊特点，使这一壮观的表现是：(1)它的电子源是场发射型单色；(2)显微镜中最重要透镜的像差校正器，消除了因球差引起的图像模糊；(3)高分辨率电子能量损失和能量色散x射线光谱仪，可以在纳米尺度上以无与伦比的精度确定化学成分和成键类型。此外，这台显微镜将配备一个特殊的舞台，可以改变被观察标本的空间方向，通过断层扫描创建其化学和结构的三维地图。这些将类似于许多人熟悉的x射线CAT扫描3d图像，但在材料研究方面具有更高的放大倍率和分辨率。这台显微镜将研究许多重要的材料问题，例如催化剂表面的杂质原子如何影响其高效生产石油基燃料的能力，以及半导体中的电活性掺杂原子如何在微芯片中分离到不同的位置，而不是保持空间均匀分布。这台显微镜将被安装在LeRoy Eyring固态科学中心，一个多用户设施，在材料学院。它将为外部大学和工业实验室研究人员提供前沿材料研究。

Technical Abstract.This microscope is designed to determine the spatial arrangements of atoms in solids and their chemistry/bonding with atomic resolution, to further understanding of the structure/properties relations of unique new materials. The microscope operates at up to 300 keV with a monochromated field emission electron source, a C3/C5 spherical aberration corrector for the probe forming lens, a high resolution electron energy loss spectrometer, a high count rate energy dispersive x-ray spectrometer, and a very stable high-tilt-range stage designed for tomography as well as conventional imaging. Current versions of this microscope have demonstrated 0.5 Å image spatial resolution in both annular dark field and bright field STEM and 110 meV energy resolution in electron energy loss spectroscopy. All detectors used for these modes are digital, which facilitates quantitative measurements of nanostructures and teaching. This remarkable spatial/energy resolution is sufficient for quantitative investigations of atom/chemical distributions at most important properties-determining structural features of solids such as heterophase interfaces and grain boundaries, and catalyst surfaces. Further, the aberration corrector enables use of large electron collection angles from the gun, to form very small and also very high current electron probes.The high current probes enable collection of many images and electron energy loss and x-ray spectra in relatively short times, to derive 2-dimensional chemical maps of solids with very high resolution. The stable high-tilt stage enables us to extend the mapping to 3-dimensions using tomography, a relatively new imaging method for materials science research that we will explore thoroughly, to determine its limits.This microscope will be installed and operated in the LeRoy Eyring Center for Solid State Science, a multiuser facility, in the School of Materials. It will be accessible for cutting edge materials research by external university and industrial laboratory researchers. Popular Publication AbstractThe engineering properties of all materials, such as structural aerospace alloys and electronic material microchips for computers and cell phones, depend on the geometric arrangements and chemical identities of the atoms that comprise the materials. These relationships are called ?structure-properties relations? and they are the major part of the field of materials science and engineering for all types of materials. The role of microscopies in materials science and engineering is to determine the structure of the materials in this relationship. Electron microscopy, in particular high resolution analytical transmission electron microscopy, is the highest resolution method that we have to determine the structures part of this relationship. The microscope to be acquired during this project is just at the cutting edge of electron microscope capability, and will produce many new and exciting results from new advanced materials to enhance our nations competitive position in nanotechnology, and it will provide essential education in nanomaterials characterization for our university students. This microscope will achieve 0.5 Ångstrom ( 0.00000001 centimeter, or less than 1 atom diameter) spatial resolution in images, and about 0.001 electron volt (1 meV) energy resolution in nanospectra, to determine chemical bonding in materials at essentially the atomic scale. The special features of this microscope that enable this spectacular performance are: (1) its electron source which is field emission type with a monochromator; (2) an aberration corrector for the most important lens in the microscope, which eliminates image blurring caused by spherical aberration; and (3) high resolution electron energy loss and energy dispersive x-ray spectrometers which can determine chemical composition and bonding type at the nanoscale with unparalleled accuracy. In addition, this microscope will be fitted with a special stage that can change the spatial orientation of the specimen under observation to create 3-dimensional maps of its chemistry and structure using tomography. These will be similar to the x-ray CAT scan 3-D images familiar to many people, but at much higher magnification and resolution for materials research. There are a host of important materials problems that will be investigated using this microscope, such as how impurity atoms on the surface of catalysts affect their ability to efficiently produce petroleum-based fuel, and the how electrically active dopant atoms in semiconductors may segregate to various locations in microchips instead of maintaining a spatially uniform distribution. This microscope will be installed and operated in the LeRoy Eyring Center for Solid State Science, a multiuser facility, in the School of Materials. It will be accessible for cutting edge materials research by external university and industrial laboratory researchers.