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Question
How will you distinguish between the following pair of terms?
Tetrahedral and octahedral voids
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Solution
| Tetrahedral void | Octahedral void | |
| 1. | The tetrahedral void is the name given to the vacant space formed by the touching of four spheres, as shown in the figure. |
Octahedral voids are formed by the combination of voids of two triangular layers of atoms when one triangular layer is placed above another, as shown in the figure. |
| 2. | A tetrahedral void is surrounded by 4 atoms arranged at the corners of a tetrahedron. | An octahedral void is surrounded by 4 atoms arranged at the corners of an octahedron. |
| 3. | Found in close-packed structures like fcc and hcp. | Only present in close-packed structures. |
| 4. | Smaller in size compared to octahedral voids. | Larger in size than tetrahedral voids. |
| 5. | Number of tetrahedral voids = 2 × number of atoms in the lattice | Number of octahedral voids = equal to number of atoms in the lattice |
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(i) A tetrahedral void is formed when a sphere of the second layer is present above triangular void in the first layer.
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