Abstract: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.

Key words: metal oxide; surface phase diagram; interface phase diagram; equilibrium crystal shape; first-principles; thermodynamics