Determination of PVTx properties of dense H2O+NaCl solutions to 5 GPa, 600 °C, and 50 wt% NaCl

流体系统的PVTx性质近似于自然流体的行为，对实验地球化学和岩石学的研究至关重要。本文提出的项目的主要目标是使用布里渊光谱和改进的水热金刚石砧室以目前可达到的最大精度确定5GPa、600°C和50wt%NaCl的致密H2O+NaCl溶液的摩尔体积。所获得的数据将扩展数据库的数量级的压力，并将作为基础，推导出适用于高流体密度的经验状态方程，这个根本上重要的水电解质系统。此外，我们打算确定的PT位置的液相线，这是知之甚少的H2O+NaCl系统在400 MPa以上的压力。另一个重要的目标是石英作为拉曼光谱压力传感器在2 GPa以上的压力下的校准，这将提高在同时高压和高温下使用水热金刚石砧室进行定量实验研究的可能性。最后，布里渊散射测量将允许确定的折射率的H2O+NaCl溶液，除了声速。

Knowledge of the PVTx properties of fluid systems, which approximate the behavior of natu-ral fluids, is crucial in experimental geochemistry and petrology. The primary goal of the project proposed here is to determine molar volumes of dense H2O+NaCl solutions to 5 GPa, 600°C, and 50 wt% NaCl with the maximum currently attainable precision using Brillouin spectroscopy and a modified hydrothermal diamond-anvil cell. The acquired data will extend the database by an order of magnitude in pressure and will serve as the basis to derive an empirical equation of state applicable to high fluid densities for this fundamentally important water-electrolyte system. Furthermore, we intend to determine the PT location of the liq-uidus, which is poorly known in the H2O+NaCl system at pressures above 400 MPa. Another important goal is the calibration of quartz as Raman spectroscopic pressure sensor at pres-sures above 2 GPa, which will enhance the possibilities of quantitative experimental studies at simultaneously high pressures and temperatures using hydrothermal diamond-anvil cells. Finally, Brillouin scattering measurements will allow the determination of the refractive index of H2O+NaCl solutions, in addition to the sound velocity.