Sound velocity measurement in liquid water up to 25 GPa and 900 K: Implications for densities of water at lower mantle conditions
Sound velocity measurement in liquid water up to 25 GPa and 900 K: Implications for densities of water at lower mantle conditions
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DOI：
10.1016/j.epsl.2009.11.037
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发表时间：
2010-01
影响因子：
5.3
通讯作者：
Y. Asahara;M. Murakami;Y. Ohishi;N. Hirao;K. Hirose
中科院分区：
文献类型：
--
作者：
Y. Asahara;M. Murakami;Y. Ohishi;N. Hirao;K. Hirose
利用激光加热金刚石对顶砧装置和布里渊散射与同步辐射X射线衍射相结合的系统，将液态水声速测量的压力范围沿熔化曲线扩展到25 GPa和沿着900 K。通过求解冰的融化曲线和金的状态方程，得到了实验压力和温度。利用Murnaghan状态方程拟合了1GPa下体积弹性模量的压力导数参数，将高压和熔化温度下液态水的声速转换为密度。结果与先前报道的基于声速测量的水的状态方程预测的值吻合良好。在这项研究中得到的水的状态方程可以适用于在下地幔条件下的冷俯冲板中的致密含水镁硅酸盐相的脱水反应释放的水，虽然Murnaghan的水的状态方程的有效性应在更宽的压力和温度范围内进行评估。目前的速度数据提供了基础，为今后改进的准确的热力学模型，在高压下的水。
We extended the pressure range of sound velocity measurements for liquid water to 25GPa and 900K along the melting curve using a laser heated diamond anvil cell with a combined system of Brillouin scattering and synchrotron X-ray diffraction. Experimental pressure and temperature were obtained by solving simultaneous equations: the melting curve of ice and the equation of state for gold. The sound velocities obtained in liquid water at high pressures and melting temperatures were converted to density using Murnaghan's equation of state by fitting a parameter of the pressure derivative of bulk modulus at 1GPa. The results are in good agreement with the values predicted by a previously reported equation of state for water based on sound velocity measurements. The equation of state for water obtained in this study could be applicable to water released by dehydration reactions of dense hydrous magnesium silicate phases in cold subducting slabs at lower mantle conditions, although the validity of Murnaghan's equation of state for water should be evaluated in a wider pressure and temperature ranges. The present velocity data provides the basis for future improvement of the accurate thermodynamic model for water at high pressures.