硅酸盐气化与凝聚过程的相平衡与化学分异

项目名称： 硅酸盐气化与凝聚过程的相平衡与化学分异

项目编号： No.41474156

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 天文学、地球科学

项目作者： 张志刚

作者单位： 中国科学院地质与地球物理研究所

项目金额： 95万元

中文摘要： 硅酸盐气体在行星形成与演化过程中发挥着重要作用，硅酸盐气化与凝聚过程的相平衡与化学分异是造成行星与地球早期物质成分与元素丰度变化的重要因素。目前人们对硅酸盐气体及其相平衡特性的认识还非常不足，高温下测定硅酸盐气液平衡性质的实验研究还很不完善，而借助热力学模型经验外推的可靠性与准确性没有保证。为此，本项目拟采用第一性原理模拟方法，结合计算几何学、统计力学以及热力学等方法，对硅酸盐气化与凝聚过程中的气固平衡、气液平衡以及各种主、微量元素在两相间的分配关系做系统研究，为研究涉及硅酸盐气体的行星演化过程提供关键性约束，从而促进我们对星云凝聚机理、地球早期大撞击、月球起源等重要科学问题的理解。

中文关键词： 硅酸盐气体；相平衡；化学分异；第一性原理；地球早期

英文摘要： Silicate vapors play important roles in the planetary formation and accretion. Phase equilibria and chemical fractionation in silicate vaporizations and condensations have been recognized to be indispensible for the variations of compositions and element abundance in the early earth and terrestrial planets. Present knowledge of the properties of silicate vapors and their phase equilibria is extremely scarce, the experimental measurements of vapor-liquid phase equilibria of silicates in high temperature regime are still in the infancy, and the extrapolations with the aid of empirical thermodynamic models turn out to be unreliable or even erroneous. Utilizing first principles simulations, combining techniques of computational geometry, statistical mechanics and thermodynamics, we propose to systematically study the solid-vapor and liquid-vapor phase equilibria of silicates and the accompanying fractionations of major and minor elements. From the simulation and modeling results, we aim at providing vital constraints for the study of planetary accretion events related with silicate vapors, which would be helpful for our understanding of relevant disputed scientific problems such as condensation mechanism of solar nebula, giant impact in the early earth and the formation mechanism of the moon.

英文关键词： silicate vapor;phase equilibria;chemical fractionation;first principles;early earth