type of voids

A student wants to arrange 4 identical spheres (of radiusR) on a two dimensional floor as close as possible. Finally he could arrange them. Identify the type and dimensions of the figure obtained by joining their centers. Could he occupy the whole available space, if not, then what type of voids were generated. Calculate their number and radius of small ball that can be fitted in them.

The type of void present at the centre of CCP is

The type of void present at the centre of the ccp unit cell is

Interstitial Void || Types OF Voids/Planner/Non-Planar voids ||Planner Voids/Triangular/Square Planar || Non-Planar Voids/tetrahedral/Octahedral/Cubical || r/R Ratio for each type OF void (v.v imp)