Self Interstitial defect in elemental solid : The empty spaces or voids in between the particles at lattice points represent interstitial defective sites or self interstitial defects.
This defect arises in the following two ways :
(1) An extra particle occupies the empty interstitial space. This extra particle is similar to those already present in the crystal.
(2) (i) A particle gets shifted from its original regular site to an empty interstitial space in the crystal.
(ii) This displacement of a particle produces a vacancy defect at its regular site.
(iii) This defect is referred to as a combination of vacancy defect and self interstitial defect.
(iv) Since there is neither loss or gain in mass of the substance, the density of it remains unchanged.
