In a FCC lattice , atoms A occupy the corner positions and atoms B occupy the face centre positions. If one atom of B is missing from one of the face centred points, calculate the formula of the compound

Asked by akash9322793205 | 12th Aug, 2021, 09:30: AM

Expert Answer:

In a face centered cubic lattice, atom (A) occupies the corner positions. There are 8 corner positions and each position contributes one eighth to the unit cell. Hence, total number of (A) atoms per unit cell= 1 over 8 cross times 8 equals 1


Atom (B) occupied the face centre positions. There are six face centre positions. One atom of (B) is missing from one of the face centered points. Thus, there are 5 face centre positions that are occupied with (B). Each such position contributes one half to the unit cell. Hence, total number of (B) atoms per unit cell.= 1 half cross times 5 equals 2.5

The formula of the compound is AB2.5 
                                               A2 B5

Answered by Ravi | 12th Aug, 2021, 12:01: PM