💡 The body center octahedral void is surrounded by 6 face-centered atoms forming a regular octahedron.
Octahedral Voids in an FCC Unit Cell
Locate octahedral voids in an FCC crystal, understand their geometry, and connect them to NaCl-type structures.
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Key Concepts
Octahedral Coordination
An octahedral void is surrounded by 6 atoms, giving a coordination number of 6.
Position & Count in FCC
In an FCC unit cell there are 4 octahedral voids: 1 at the body center and 12 at edge centers shared by 4 cells.
Crystal Examples
NaCl is a classic structure where the anions form an FCC lattice and the cations occupy all octahedral voids.
Understanding Octahedral Voids
**Octahedral Voids** are the interstitial spaces in a crystal lattice surrounded by six nearest-neighbor atoms. In a **Face-Centered Cubic (FCC)** unit cell, these voids are systematically positioned at the body center and at the center of each of the twelve edges.
The geometry of an octahedral void is defined by a coordination number of 6. Each FCC unit cell contains a total of **four octahedral voids** (1 body-center void + 12 × 1/4 edge-center voids), matching the number of lattice atoms per cell.
Explore our interactive model to visualize how iconic structures like **Sodium Chloride (NaCl)** are assembled, where larger ions form the FCC framework while smaller ions occupy all available octahedral voids.
Frequently Asked Questions
Related Simulations
Tetrahedral Voids
A **Tetrahedral Void** is the interstitial space surrounded by four atoms in a tetrahedral arrangement. This resource locates the eight tetrahedral voids within a **Face-Centered Cubic (FCC)** unit cell.
Cubic Close Packing
**Cubic Close Packing (CCP)** is a high-efficiency crystal structure where atoms are arranged in an **A-B-C** stacking sequence. This resource visualizes the **Face-Centered Cubic (FCC)** unit cell and its 74.05% packing efficiency.
Hexagonal Close Packing
**Hexagonal Close Packing (HCP)** is a high-efficiency crystal structure with an **A-B-A-B** stacking sequence. This resource explores the **Hexagonal Unit Cell** and its 74.05% packing density.