Effect of combined local variations in elastic and inelastic energy losses on the morphology of tracks in ion-irradiated materials

Abstract

Detailed analysis of the morphology of latent tracks created by swift heavy ions from the surface entry point on a pyrochlore crystal to the end of the ion trajectory reveals continuous changes in the track diameter as a function of ion deceleration, loss of track parallelism beyond a certain depth and the evolution from continuous to discontinuous tracks. The tracks exhibit a layered structure composed of a non-crystalline core surrounded by a strained crystalline envelope. Furthermore, surprising local increases in the diameter of the latent tracks are readily observed. This feature can be interpreted using a model based on the concept of effective local energy deposition, defined as the sum of the inelastic energy deposited by the swift track-forming ion and the elastic energy deposited by a primary knock-on atom inside the ion track.