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Calculate the number of particles per unit cell in fcc. |
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Answer» Solution :: (i) The primitive unit cell consists of one atom at each of the 8 corners, each atom is thusshared by 8 unit cells. Hence N = `8 xx (1//8) = 1` (II) The b.c.c unit cell consists of 8 atoms at the 8 corners and one atom at the centre. At each corner only`1//8^(th)` of theatom is within the unit cell. Thus the contribution of the 8 corners is `8 xx (1//8) = 1` while that of the body-centred atom is 1. Hence, n = 1+1 =2 (iii) The 8 atoms at the corners contribute 8 x (1/8) = 1 atom. There is one atom each of the 6 FACES, which is shared by 2 unit cells each. Therefore, the contribution face-centred atoms = 6x (1/2) = 3 Hence, n = 1+3 = 4. |
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