which
lattice points are not correctly
matched in the following?
© Face . centred cubic : 14.
face centred
tetragonal 14
body centre cubic :9
d)
simple cubic :12
Answers
Answer:
i) Face-centred cubic
8 lattice points at corners and 6 lattice points at face centres are present in face-centred cubic.
A corner lattice point contributes one eight to the unit cell and a lattice point at face centre contributes one half to the unit cell.
Total number of lattice points per unit cell: 8×
8
1
+6×
2
1
=1+3=4
(ii) Face-centred tetragonal
8 lattice points at corners and 6 lattice points at face centres.
A corner lattice point contributes one eight to the unit cell and a lattice point at face centre contributes one half to the unit cell.
Total number of lattice points per unit cell: 8×
8
1
+6×
2
1
=1+3=4
(iii) Body-centred
8 lattice points at corners and 1 lattice point at body centre.
A corner lattice point contributes one eight to the unit cell and a lattice point at body centre contributes one to the unit cell.
Total number of lattice points per unit cell: 8×
8
1
+1×1=1+1=2