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Thermodynamics of Surfaces; Equilibrium Crystal Shape. Course will primarily focus on: atomic structure and electronic properties, chemical composition and adsorption properties of surfaces.
10 wrz 2020 · However, from the point of view of thermodynamics, it is easier to think of surface energy. How much work is needed to increase the surface area? And how is this related to what we have described as “surface tension”?
The units of surface tension are free energy per unit area, [J/m2] or force per unit length, [N/m]. Surface tension is linked to several known physics experiment: For instance, molecules at the surface of a liquid forms stronger bonds than the molecules inside the liquid.
For solid-solid interfaces, it is an integral energy, such as adhesion energy, which is determined. Furthermore, the equation (13) requires that a decrease in surface free energy implying a positive adsorption at the interface.
Surface free energy is: Gs = Hs – TSs. Work Needed to Create A Surface of one Component: Surface Tension. Surface area is increased by moving atoms from the bulk to the surface and then to move surface atoms out of the way to make room for the new surface atoms.
Surfaces impact the free energy. It takes energy to form surfaces. Small particles dissolve easier. There are limits to grinding, fine powdered sugar; about 50μm. Aggregates versus primary particles. Nitrogen (or Argon) adsorption. Other methods: SAXS. TEM SEM OM XRD (Scherrer Equation) Aerosol Methods (DMA) Aggregates versus primary particles.
Free energy is considered afresh, as a suitable way of treating equilibrium conditions under various constraints. Availability is defined and used. The general concept of a system finding its equilibrium via the adjustment of internal parameters is described.
