Acquisition of Equipment to Establish a High-Pressure Single-Crystal X-Ray Laboratory

购置设备建立高压单晶X射线实验室

• 批准号: 0131979
• 负责人: George Lager
• 金额: $ 5.55万
• 依托单位: University of Louisville Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-03-15 至 2004-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0131979&HistoricalAwards=false
• 关键词: Acquisition; Equipment; Establish; Pressure; Single

0131979LagerA high-pressure, single-crystal X-ray diffraction laboratory will be established at the University of Louisville. An existing, fully operational CAD4 diffractometer will be adapted for high-pressure use with a diamond-anvil cell. The laboratory will also house an electrostatic drilling machine and stereomicroscope for loading the cell and a laser spectrometer for pressure calibration. A second X-ray unit will also be upgraded with a solid-state generator. A precession camera mounted on this unit will be used as a check on crystal quality and to determine the orientation of single crystals in the pressure cell. The new laboratory will be dedicated to studies of hydrous minerals at high pressure. This group of earth materials plays an important role in mantle processes related to earthquake activity. For example, volume changes associated with phase transitions in hydrous minerals have been linked to the localization of stress and the occurrence of earthquakes along subduction zones. Experiments in this project will focus on hydrous magnesium silicate (OH-clinohumite) and hydrogarnet. Phase-equilbria studies indicate that clinohumite is a stable water-bearing phase in subduction zones to depths of ~400 km (transition zone). Its high-pressure infrared spectrum shows several anomalies at ~13 GPa. The possibility that these anomalies are related to a phase transition will be investigated using the converted CAD4 diffractometer system. Synthetic Si-free hydrogarnet (katoite) has been used as a model to understand how OH is incorporated in silicate garnets that occur in the crust and mantle. The katoite structure undergoes a phase transition at 5 GPa. X-ray data will be collected with the CAD4 at high pressures to determine if a similar transition is observed in naturally occurring hydrogarnets. ***

0131979 LagerA高压单晶X射线衍射实验室将在路易斯维尔大学建立。一台现有的、可全面运行的CAD 4衍射仪将被改造成金刚石压砧单元，用于高压使用。该实验室还将容纳一台静电钻孔机和立体显微镜，用于加载细胞和激光光谱仪进行压力校准。第二台X射线装置也将升级为固态发生器。安装在该装置上的旋进相机将用于检查晶体质量并确定压力单元中单晶的取向。新实验室将致力于高压下含水矿物的研究。这类地球物质在与地震活动有关的地幔过程中起着重要作用。例如，与含水矿物相变有关的体积变化与应力的局部化和沿着俯冲带的地震发生有关。本项目的实验将集中在含水镁硅酸盐（OH-斜腐植岩）和水石榴石。相平衡研究表明，在深度约400 km的俯冲带（过渡带）中，斜腐植岩是稳定的含水相。它的高压红外光谱在~13 GPa处显示出几个异常。这些异常与相变有关的可能性将使用转换后的CAD 4衍射仪系统进行研究。合成无硅水石榴石（Katoite）已被用来作为一个模型，以了解OH是如何纳入硅酸盐石榴石发生在地壳和地幔。Katoite结构在5GPa下经历相变。将在高压下用CAD 4收集X射线数据，以确定在天然存在的水石榴石中是否观察到类似的转变。***