MRI: Development of Six New Approaches for Micro-focus Single-Crystal X-Ray Diffraction for Materials Structure Research at Synchrotrons

同步加速器技术的最新进展使光束斑点小于1微米的X射线衍射成为可能。这些进展为研究化学、物理、材料科学、工程学、生物学和地球科学中的材料结构创造了许多新的可能性，可以提高我们对地球、新材料、材料失效和生命本身的理解。然而，用如此强烈、紧凑的光源和微晶体进行的实验，将粉末衍射转变为单晶体或少数晶体研究，可能会产生关于结构的更多细节。这一开发项目的主要目标是使微米源和样品的X射线衍射结构分析与大样品研究一样简单和高效，并开发用于仪器控制和数据分析的软件，这些软件将容易地转移到这些应用的广泛领域和许多同步加速器上。该项目建立在Dera、Down、MAO、Prewitt和Somayazulu的工作基础上，使微米级的单晶衍射研究能够在兆巴压力下的钻石顶压室中进行，Denton为这些应用开发新型探测器，以及在高级光子源和高级光源上提供新的微聚焦衍射光束线。虽然在超高压下研究材料是这些发展的特别重点，但结果在衍射工作中的潜在应用在科学和工程中得到了广泛的应用。我们计划开发的微米样品结构测定的新实验方法包括：使用有限面积探测器数据和单色源快速确定单胞，使用点探测器确定峰强度；使用高精度旋转台和快速面积探测器在一个振荡模式中收集完整的数据集，并用高效算法计算单胞参数；自动化组合劳埃和EDX方法确定单胞尺寸，并将其扩展到结构解决方案应用；研制了一种箔式掩模X射线面探测器光谱仪，该谱仪采用能量选择掩模隔开的叠层CMOS探测器，通过步进扫描单色辐射和使用高速读出探测器来分辨劳厄峰的能量。X射线源的最新进展使微米和纳米束斑的X射线研究成为可能，并为理解对化学、物理、材料科学、工程、生物学和地球科学重要的结构创造了新的可能性。可以对粉末、岩石和金属合金中的细小颗粒进行详细的结构分析。对材料因应力而变形的应变的工程分析将扩展到小得多的尺寸。天然或重要技术材料的结构将在极端的压力(超过一百万个大气压)和温度(从接近绝对零度到超过8000摄氏度)的条件下确定。这些研究将有助于提高我们对地球、新材料、材料失效和生命本身的理解。该项目的主要目标是用小样本的X射线进行结构分析，就像用自动商业X射线仪器进行结构分析一样简单。虽然在极高压力下研究材料是这些发展的特别重点，但将结果应用于仪器控制和数据分析的技术和软件将很容易转移到科学和技术的广泛应用中。

Recent advances in the synchrotron technology make possible X-ray diffraction with beam spots smaller than a micrometer. These advances create many new possibilities for studying structures of materials in chemistry, physics, materials science, engineering, biology and geosciences that can improve our understanding of our planet, new materials, failure of materials, and life itself. Experiments with such intense, compact sources and microcrystals, however, change powder diffraction to a single- or few-crystal studies that may yield much more detail about structures. The principal goals of this developmental project are to make structural analysis by X-ray diffraction with micrometer sources and samples as straightforward and productive as studies with larger samples and to develop software for instrument control and data analysis that will readily transfer to a wide range of these applications and many synchrotrons. The project builds upon work by Dera, Downs, Mao, Prewitt, and Somayazulu to enable single-crystal diffraction studies with samples of micron dimensions in diamond-anvil cells at megabar pressures, work by Denton to develop novel detectors for these applications, and the availability of new micro-focus diffraction beamlines at the Advanced Photon Source and Advanced Light Source. While studying materials at extremely high pressures is the particular focus for these developments, potential applications of the results for diffraction work extend broadly in the sciences and engineering. Among the novel experimental approaches to structural determination with micron samples we plan to develop are: using limited area detector data with a monochromatic source to determine rapidly unit cells and determining peak intensities with a point detector; using high precision rotation stages and fast area detectors to collect a full data set in one oscillation pattern and computing unit cell parameters with efficient algorithms; automating a combined Laue & EDX approach for determining unit cell dimensions and extending it towards structure solution applications; developing a foil-mask X-ray area detector spectrometer based on stacked CMOS detectors separated by energy-selective masks, and resolving energies of Laue peaks by step-scanning monochromatic radiation and using high-readout-speed detectors. Recent advances in the x-ray sources make possible X-ray studies with micrometer and nanometer beam spots and create new possibilities for understanding structures important to chemistry, physics, materials science, engineering, biology and geosciences. Detailed structural analyses can be done for fine grains within powders, rocks, and metal alloys. Engineering analyses of the strains in materials being deformed by stresses will be extended to much smaller sizes. Structures of natural or important technological materials will be determined under extreme conditions of pressure (more than a million atmospheres) and temperatures (from near absolute zero to more than 8000 degrees Celsius). These studies will help to improve our understanding of our planet, new materials, failure of materials, and life itself. The principal goal of the project is to make structural analysis with X-rays of small samples as simple as those done with automated commercial X-ray instruments. While studying materials at extremely high pressures is the particular focus for these developments, applications of the results for the techniques and software for instrument control and data analysis will readily transfer to a wide range of applications in science and technology.