Question

How many atoms are present in end centred cubic unit cell?

Answer 1

End centred cubic unit cell:

• 8 atoms are present on 8 corners, where each atom contributes ($1/8$)th portion of the cell.
• 2 atoms are present at the centre of the cell, where each atom contributes ($1/2$) portion of the cell.
• The number of atoms in an end centred cubic unit cell = Number of atoms at the corners + Number of atoms at the centre.
• The number of atoms in an end centred cubic unit cell = $8\times (1/8)+2\mathrm{x}(1/2)$ = 2 atoms.

Hence, 2 atoms are present in end centred cubic unit cell.