Epitaxial Growth of Gibbsite Sheets on the Basal Surface of Muscovite Mica

The
growth of aluminum (oxyhydr)­oxide films on the basal surface
of muscovite mica is an excellent model system for studying mineral
nucleation, growth, and reactivity. Using off-specular crystal truncation
rod X-ray scattering, we have determined the atomic-scale epitaxial
relationships between muscovite and monolayer overgrowths of a gibbsite-like
material. We observe that dioctahedral sheets of aluminum (oxyhydr)­oxide
grow in three structurally distinct domains, separated by antiphase
boundaries. Vacancies in the dioctahedral sheets overlie either the
silicate tetrahedra or the ditrigonal cavities of the underlying muscovite
surface. High-resolution atomic force microscopy indicates lateral
island sizes of ∼10 nm separated by 1–2 nm spaces. Together,
the X-ray and microscopy data provide insights into the coordination
chemistry and morphology of films formed by heterogeneous nucleation
and growth.