By Hussain AhmedFeb 1 2023Reviewed by Megan Craig, M.Sc. Muscovite mica is a common layered phyllosilicate mineral with perfect cleavage planes. These atomically flat surfaces are ideal for studying minerals and clays using scanning probe techniques with atomic resolution. However, there are still unresolved questions about ordering K+ ions on the cleaved surface.
Over the past few decades, muscovite mica has been the attention of numerous studies across various fields, including environmental science, nanotribology, and developing next-generation electronics based on two-dimensional materials. Moreover, the flatness and simplicity of mica production have made it the preferred test system for novel experimental methods with real-space, molecular precision in atmospheric or liquid settings that go beyond the classic atomic force microscope .
The existence of Al short-range ordering has been postulated by early nuclear magnetic resonance and Monte Carlo calculations. Through electrostatic contact, such ordering might influence the distribution of surface K+ ions. However, owing to the difficulties of analyzing intrinsic surface K+ distributions, proving this idea in atmospheric conditions remains a major challenge.
The results obtained from these imaging techniques were then analyzed using a combination of density functional theory calculations and Monte Carlo simulations. The DFT calculations were used to understand the distribution of the K+ ions. In contrast, the MC simulations were used to gain more information on the Al3+ order based on the measured surface K+ order.