Chemistry - Solid State Question with Solution | TestHub

The radius ratio is the ratio of the radius (r) of the atom or ion which can exactly fit in the octahedral void formed by spheres of radius $R$. For trigonal voids, the radius ratio is $0.155$. For tetrahedral voids, the radius ratio is $0.225$. For octahedral voids, the radius ratio is $0.414$. For cubic voids, the radius ratio is $0.732$. Thus, the limiting radius ratio for tetrahedral structure is $0.225-0.414$.