How many `TVs` and `OV s` occur per unit cell and per atom in a closest packed structure?

Explanation

To determine how many tetrahedral voids (TVs) and octahedral voids (OVs) occur per unit cell and per atom in a closest packed structure, we can follow these steps:

### Step 1: Understanding Closest Packed Structures
In a closest packed structure, such as face-centered cubic (FCC) or hexagonal close-packed (HCP), the arrangement of spheres leads to the formation of voids.

### Step 2: Tetrahedral Voids per Unit Cell
In a closest packed structure, there are a total of **8 tetrahedral voids** per unit cell. This is derived from the arrangement of spheres where tetrahedral voids are formed in the spaces between the spheres.

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