radius ration#!#3D packing

At the limiting value of radius ration (r^+)/(r^-)

2D and 3D closed packing

In closest packing of A type of atoms (radius r_(A) ) the radius of atom B that can be fitted into octabedral voids is

For the closest packing of atoms A (radius, r_(A) ), the maximum radius of atom B that can be fitted into octahedral void is

In the closed packing of atoms A ("radius":r_(a)) , the radius of atom B that can be fitted into tetrahedral void is: