In octahedral holes (voids):

Options

A. A simple triangular void surrounded by four spheres
B. A bi-triangular void surrounded by four spheres
C. A bi-triangular void surrounded by six spheres
D. A bi-triangular void surrounded by eight spheres

Answer

To understand octahedral holes (voids) in the context of solid-state chemistry, particularly in face-centered cubic (FCC) structures, we can break down the explanation into clear steps:

### Step-by-Step Solution:

1. **Understanding the FCC Structure**:
- In a face-centered cubic (FCC) lattice, the atoms are located at each of the corners of the cube and at the centers of each of the cube's faces.

2. **Identifying Octahedral Voids**:
- An octahedral void is a type of interstitial site where smaller atoms can fit within the lattice structure. In an FCC lattice, octahedral voids are formed in specific locations.

3. **Location of Octahedral Voids**:
- In the FCC structure, octahedral voids are located at:
- The center of the cube (1 void).
- The edge centers (12 edges, with 1/4 of a void contributed by each edge, totaling 3 voids).

4. **Visualizing the Octahedral Void**:
- Imagine a cube where the atoms at the corners and face centers touch each other. The octahedral void is formed at the center of the cube, surrounded by six atoms (the four face-centered atoms and the two corner atoms).

5. **Understanding the Geometry**:
- The octahedral void can be visualized as a bi-triangular arrangement where two triangular planes are formed by the atoms, and the void is located in the center of these two triangles. This structure is surrounded by six spheres (the atoms).

6. **Conclusion**:
- Therefore, the octahedral void in an FCC structure is a bi-triangular void surrounded by six spheres. This is the correct identification of the octahedral void in the context of the FCC lattice.

### Final Answer:
The octahedral void is a bi-triangular void surrounded by six spheres.

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