Calculation of the radius of an octaedral interstitial site in a face-centered cubic lattice: R<sub>O</sub> = a/2 - r ≃ 0,41r.
<a href="//commons.wikimedia.org/wiki/User:Cdang" title="User:Cdang">Cdang</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>