Collaborative Research: High Pressure Calibration at High Temperatures

0842057/0842345 Goncharov/BASS该奖项由2009年《美国复苏和再投资法案》(公法第111-5条)资助。这项提议寻求约47.8万美元的资金，以支持为钻石顶锤单元(DAC)研究开发高压、高温校准标尺。现有的压力表存在问题，特别是在高温情况下。提出了一种利用X射线衍射法进行密度测量，同时利用立方氮化硼(CBN)的布里渊散射进行声速测量的压力标尺。此外，还将进行拉曼P和T测量。PI建议通过将方法耦合到单个压力表中，在不同温度和压力下通过其状态方程将其他材料与CBN相参照。由于材料的性质在高温高压下会发生变化，因此在DAC研究中很难将压力归因于材料。压力和温度效应已经在许多材料和测量技术(X射线、光学、荧光等)中被注意到。在DAC研究范围内，CBN的晶体结构在理论上对至少1000 Gpa的相变是稳定的，因此被认为是一种潜在的压力刻度校准剂。DAC研究以及校准的压力表将允许研究地球内部的材料相变，地球材料热性质研究和状态方程确定，以及材料相稳定性和化学。这项研究将产生一种初级压力表--在惰性材料上进行校准，适用于高T&P工作。这一结果将允许在高T&P下进行准确的X射线衍射、X射线光谱和X射线散射测量，这反过来又将允许对地球深部物质进行理论状态方程计算。研究结果将广泛影响地球物理、矿物物理、地球化学和地球动力学。学习将包括REU学生(每个暑假2-3人)。研究生是博士后，也建议进行培养。

0842057 / 0842345Goncharov / BassThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). This proposal seeks ~$478K in funding to support developing a high pressure, high temperature calibration scale for diamond anvil cell (DAC) studies. Existing pressure scales are plagued with issues particularly at high temperatures. Developing a pressure scale is proposed by performing density measurements by x-ray diffraction and concurrent sound velocity measurements using Brillouin scattering on cubic boron nitride (cBN). In addition, Raman P and T measurements will be made. The PIs propose to reference other materials though their equation of state to cBN at varying temperatures and pressures by coupling methodologies into a single pressure scale. Because material properties change under high pressure and temperature, it has been difficult to ascribe pressure exerted on materials in DAC studies. Pressure and temperature effects have been noted for numerous materials and measurement techniques (X-ray, optical, fluorescent, etc). cBN is suggested as a potential pressure scale calibrant as it's crystal structure is theoretically stable to phase transformation up to at least 1000 GPa within the range of DAC studies. DAC studies along with the calibrated pressure scale will allow studies into material phase transitions in the Earth's interior, Earth material thermal property studies and equation of state determinations, and material phase stability and chemistry. This study will result in a primary pressure scale - calibrated on an inert material and suitable for high T&P work. The outcome will allow accurate X-ray diffraction, X-ray spectroscopy, and X-ray scattering measurements under high T&P. This, in turn, will allow theoretical equation of state calculations for deep Earth materials. Results will broadly impact geophysics, mineral physics, geochemistry and geodynamics. Studies will involve REU students (2-3 per summer). Graduate students are post-docs are also proposed for training.