Measurement of the Gibbsian interfacial excess of solute at an interface of arbitrary geometry using three-dimensional atom probe microscopy

We show how the Gibbsian interfacial excess of solute can be calculated from three-dimensional atom probe data, even in the case of irregularly shaped interfaces. Standard treatments of interfacial thermodynamics implicitly define a one-dimensional geometry for an interface by assuming a planar interface. Of course, many real systems exhibit non-planar interfaces, and these treatments are difficult to apply. We show how our treatment derives from Gibbs' original approach and how it is used to derive real thermodynamic quantities. The technique can be applied to any interfacial excess quantity.