Q 8 How many lattice points are there in one unit cell of each of the following lattice?
(i) Face–centred cubic
(ii) Face–centred tetragonal
(iii) Body–centred
Solution: :–
(i) Face–centred cubic
(i) A face–centred cubic (fcc) unit cell contains atoms at all the corners and at the centre of all the faces of the cube.
So lattice point at the corner = 8
Lattice point at the center of all faces = 6
Total number of lattice point = 14
(ii) Face–centred tetragonal
lattice point at the corner = 8
Lattice point at the center of all faces = 6
Total number of lattice point = 14
(iii) Body–centred
In Body centered cubic there are 8 lattice point at the corner and 1 is at the center so total 8+1 =9 lattice point
