Question

The limiting radius ratio for tetrahedral shape is___________.

• A. $0-0.155$
• B. $0.155-0.225$
• C. $0.225-0.414$
• D. $0.414-0.732$

Answer 1

Answer: (C)

$0.225-0.414$

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 $0.225-0.414$.