When PKAs receive energy greater than E from bombarding electrons , they are able to displace more atoms .
Some of the Frenkel defects become groups of interstitial atoms with corresponding vacancies , within a few interatomic distances of each other .
When PKAs receive energy greater than E from bombarding electrons , they are able to displace more atoms , and some of the Frenkel defects become groups of interstitial atoms with corresponding vacancies , within a few interatomic distances of each other .