金属氧化物表面与界面的第一性原理热力学:一个研究实例

通过第一性原理计算研究,能够揭示和阐明材料相关表面与界面热力学性质,这是通向纳米和界面材料设计自由的重要一步,即以理想性能为目标,科学设计制备工艺参数,针对性地调控材料微观结构.以SnO2纳米颗粒表面和原位内氧化制备获得的Ag-SnO2界面计算研究为例,系统介绍这一计算研究策略.基于缺陷热力学模型,构建不同环境温度和氧分压条件下所对应的热力学平衡状态的表面和界面结构模型,计算评估其相应性能.通过一系列的第一性原理能量学计算,进一步构建出平衡状态的表面与界面相图.这些相图能够充分描述制备和服役过程中,工况对材料表面和界面微观结构和相应性能的影响和作用关系.介绍和讨论如何应用这些相图理解和科学设计相应材料的制备工艺.

First-principles thermodynamics of metal-oxide surfaces andinterfaces:A case study review

An important step for achieving the knowledge-based design freedom on nano- and interfacial materials is attained by elucidating the related surface and interface thermodynamics from the first principles so as to allow engineering the microstructures for desired properties through smartly designing fabrication processing parameters. This is demonstrated for SnO₂ nano-particle surfaces and also a technologically important Ag-SnO₂ interface fabricated by in-situ internal oxidation. Based on defect thermodynamics, we first modeled and calculated the equilibrium surface and interface structures, and as well corresponding properties, as a function of the ambient temperature and oxygen partial pressure. A series of first principles energetics calculations were then performed to construct the equilibrium surface and interface phase diagrams, to describe the environment dependence of the microstructures and properties of the surfaces and interfaces during fabrication and service conditions. The use and potential application of these phase diagrams as a process design tool were suggested and discussed.