Thermodynamics of solid solutions based on first-principles simulations of supercells of host phases with defects of the solute component

该项目概述了两种新的方法来模拟地球化学和岩石学上重要的固体溶液的过剩和标准热力学性质。双缺陷方法(DDM)考虑的是同构解，即由属于同一空间群的端元形成的体系，例如方解石-菱镁矿。单缺陷法(SDM)处理非等结构体系，如CaSO4在方解石中的固溶体。DDM与浓固溶体有关，能够描述短程和长程有序的影响，而SDM适用于稀释固溶体，能够预测分散在主体相中的虚拟(痕量)组分的浓度。这两种方法都是基于第一原理模拟具有单一或成对溶质缺陷的主体相的超晶胞结构。将受益于拟议发展的研究领域包括：微量元素地质测温法，即根据微量元素在造岩矿物之间的分布进行的测温；地质生态学，例如预测造岩矿物中有害元素的保留水平；高压矿物学，例如估计压力稳定的末端成员的热力学性质；材料科学，例如预测包括固体溶液在内的陶瓷体系的相图。

The project outlines two novel approaches to modelling of the excess and the standard thermodynamic properties of geochemically and petrologically important solid solutions. The Double Defect Method (DDM) considers isostructural solutions, i.e. systems formed by end-members, which belong to the same space group, e.g. calcite-magnesite. The Single Defect Method (SDM), deals with non-isostructural systems, e.g. the solid solution of CaSO4 in calcite. While the DDM is concerned with concentrated solid solutions and is able to describe effects of short and long-range order, the SDM is applicable to diluted solid solutions, and is able to predict concentrations of a virtual (trace) component dispersed within the host phase. Both approaches are based on first-principles simulations of supercell structures of host phases with single or paired defects of the solute. Research areas, which will benefit from the proposed developments include trace-element geothermometry, i.e. the thermometry based on the distribution of trace elements between rock-forming minerals; geoecology, e.g. the prediction of retention levels of hazardous elements in rock-forming minerals; high-pressure mineralogy, e.g. the estimation of thermodynamic properties of pressure-stabilized end-members; materials science, e.g. the prediction of phase diagrams of ceramics systems, which include solid solutions.