Question

Which of the following best describes a tetrahedral void?
A. Combination of triangular voids
B. Space within a cube
C.Unoccupied pace between $4$ spheres arranged in a tetrahedron
D.Space unoccupied between $6$ spheres.

Answer 1

The unit cell is the smallest repeating unit in a crystal lattice. When atoms or ions are packed into a cube the space will be created and the space can be called as void. There are two types of voids, tetrahedral and octahedral void. In tetrahedral void unoccupied empty spaces present are in the tetrahedral crystal system.

Complete answer:
The smallest repeating unit in a crystal lattice is known as unit cell. Generally, atoms or ions are packed in a crystal system, creating spaces. These spaces can be called voids. There are different types of voids like tetrahedral voids and octahedral voids.
In tetrahedral voids the unoccupied empty spaces are present, these all atoms and spaces were arranged in a tetrahedral crystal system. Thus, these voids are known as tetrahedral voids.
In octahedral voids the unoccupied empty spaces are present, these all atoms and spaces were arranged in an octahedral crystal system. Thus, these voids are known as octahedral voids.
Thus, tetrahedral voids are formed between $4$ spheres arranged in a tetrahedron.
Thus, option C is the correct one.

Note:
In tetrahedral voids the second layer’s sphere is just above the void of the first layer. As these voids are present in a tetrahedral system these are known as tetrahedral voids. The number of tetrahedral voids will be equal to twice of the number of the unit cells or spheres in the crystal system.