(1) Octahedral void : The vacant space or void at the centre of six spheres (or atoms) which are placed octahedrally is called octahedral void.
(2) Characteristics of octahedral void :
- The volume of the void is small.
- There is one octahedral void at the body centre and twelve octahedral void positions at twelve edge centres.
- If R is the radius of constituent atom, then the radius of the octahedral void is 0.414 R.
- The coordination number of octahedral void is six.
- There is one octahedral void per sphere in the crystal lattice. If the number of closed packed spheres is N then the number of octahedral voids is N.
