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光斑小于一微米的x射线衍射成为可能。这些进步为研究化学、物理、材料科学、工程、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，用这种强烈、紧凑的源和微晶体进行的实验，将粉末衍射变成了单晶或少晶的研究，这可能会产生更多关于结构的细节。这个发展项目的主要目标是用微米源和样品进行x射线衍射的结构分析，就像用更大的样品进行研究一样简单和富有成效，并开发仪器控制和数据分析软件，这将很容易转移到这些应用和许多同步加速器。该项目建立在Dera、Downs、Mao、Prewitt和Somayazulu的工作基础上，他们的工作是在兆巴压力下，在钻石铁质细胞中使用微米尺寸的样品进行单晶衍射研究，Denton的工作是为这些应用开发新型探测器，以及在先进光子源和先进光源上使用新的微聚焦衍射光束线。虽然在极高压力下研究材料是这些发展的特别重点，但衍射工作结果的潜在应用在科学和工程中广泛扩展。我们计划开发的用于微米样品结构测定的新实验方法包括：使用单色源的有限面积检测器数据来快速测定单位细胞，并使用点检测器确定峰值强度；利用高精度的旋转台和快速区域检测器在一个振荡模式下采集完整的数据集，并用高效的算法计算单元胞参数；自动化组合Laue & EDX方法来确定单元格尺寸，并将其扩展到结构解决方案应用；基于能量选择掩模分离的叠层CMOS探测器，采用步进扫描单色辐射和高读出速度探测器分辨劳埃峰的能量，研制了箔掩膜x射线区域探测光谱仪。x射线源的最新进展使微米和纳米光束点的x射线研究成为可能，并为理解化学、物理、材料科学、工程、生物和地球科学等重要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颗粒进行详细的结构分析。受应力变形的材料中的应变的工程分析将扩展到更小的尺寸。天然或重要的技术材料的结构将在极端的压力条件（超过一百万大气压）和温度条件（从接近绝对零度到超过8000摄氏度）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x射线对小样本进行结构分析，就像用自动商用x射线仪器做的那样简单。虽然在极高压力下研究材料是这些发展的特别重点，但仪器控制和数据分析的技术和软件的结果应用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.