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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.
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.
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”?
Gibbs considered the conditions in an isothermal and isobaric system of more than one component, such as a solution, where specific components might change the number of moles. To this aim, three main parameters should be defined: the Gibbs surface free energy G
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.
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.
The energy required to increase the surface area is referred to as the free surface energy or surface free energy γ. Not surprisingly its unit is energy per area, i.e., J m − 2, as it defines the amount of energy required in order to create a certain surface area.
