  Interfaces between demixed fluid phases of binary mixtures of hard platelets
are investigated using density-functional theory. The corresponding excess free
energy functional is calculated within a fundamental measure theory adapted to
the Zwanzig model, in which the orientations of the particles of rectangular
shape are restricted to three orthogonal orientations. Density and
orientational order parameter profiles at interfaces between coexisting phases
as well as the interfacial tension are determined. A density inversion,
oscillatory density profiles, and a Fisher-Widom line have been found in a
mixture of large thin and small thick platelets. The lowest interfacial tension
corresponds to the mean bulk orientation of the platelets being parallel to the
interface. For a mixture of large and small thin platelets, complete wetting of
an isotropic-nematic interface by a second nematic phase is found.
