Calibration of the diamond anvil Raman pressure gauge to above 500 GPa in a toroidal-DAC.

The diamond anvil Raman phonon frequency shift at the interface with the sample is now currently used as a pressure measurement for laboratory experiments above 100 GPa up to 500 GPa at least. However, the calibration of this spectroscopic pressure measurement is questioned. The aim of this proposal is twofold: 1) Calibrate the Raman diamond pressure gauge up to above 500 GPa by using the XRD and the EoS of two pressure standards, gold and Rhenium. Data have been collected up to 420 GPa so far. 2) Validate the pressure scale using the volume of diamond under hydrostatic pressure up to above 500 GPa. Data have been collected up to 200 GPa so far. The Raman shift of diamond under hydrostatic pressure will be also measured, so to provide the diamond Gruneisen parameter . Toroidal-DACs will be used to reach the 500 GPa range.

目前，在至少100 GPa至500 GPa的实验室实验中，金刚石压砧与样品界面处的拉曼声子频移已被用作压力测量手段。然而，该光谱式压力测量方法的标定工作受到了学界质疑。本研究提案的目标分为两点：1）以金与铼两种压力标准物质的X射线衍射（XRD）数据和状态方程（EoS）为依据，将拉曼金刚石压力计的标定范围拓展至500 GPa以上，截至目前已收集到最高达420 GPa的实验数据；2）利用静水压条件下最高至500 GPa以上的金刚石体积数据，对该压力标尺进行验证，截至目前已收集到最高达200 GPa的实验数据。此外，本研究还将测量静水压下金刚石的拉曼频移，以获取金刚石的格吕内森参数（Grüneisen parameter）。本次研究将采用环形金刚石对顶砧（Toroidal-DACs）以实现500 GPa级别的压力环境。