Before revision: Interstitial defect An interstitial defect is a crystal which does not normally have atoms occupying the interstitial sites by default, but has atoms occupying some of these sites at random as crystallographic defects .
After revision: Interstitial defect An interstitial defect refers to additional atoms occupying some interstitial sitesin a crystal which normally has empty interstitial sites by default at random as crystallographic defects .