Alpha-RuCl3 ($\alpha$-RuCl$_3$) exhibits a prominent layered crystal structure characterized by planes of edge-sharing ruthenium-chloride octahedra arranged in a distinct honeycomb lattice.
Key Aspects of Alpha-RuCl3's Structure
The unique structural properties of $\alpha$-RuCl$_3$ are crucial to understanding its physical behavior. Its architecture can be broken down into several key components:
- Layered Nature: The material crystallizes in a lamellar or layered structure. This means it is composed of thin, two-dimensional sheets stacked one on top of the other, similar to graphite. This layered characteristic is fundamental to its properties.
- Octahedral Units: The fundamental building blocks within each layer are RuCl$_6$ octahedra. In these units, a central ruthenium (Ru) atom is octahedrally coordinated by six surrounding chlorine (Cl) atoms.
- Edge-Sharing Arrangement: Within each plane, these RuCl$_6$ octahedra are not isolated but are intricately linked through edge-sharing. This means that adjacent octahedra share common edges, forming extended networks.
- Honeycomb Lattice: The collective arrangement of these edge-sharing RuCl$_6$ octahedra within a given plane forms a honeycomb lattice. This characteristic hexagonal pattern is a defining feature of the structure, dictating the connectivity and symmetry within the layers.
This specific combination of a layered architecture, edge-sharing RuCl$_6$ octahedra, and the formation of a honeycomb lattice is what defines the crystal structure of $\alpha$-RuCl$_3$.
