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 similar to 10nm 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.