Swift heavy ions induced nano-grain fragmentation in fluoride thin films

Influence of the swift heavy ions (SHIs) at various ion fluences in nanodimensional polycrystalline fluoride thin films (LiF, CaF2 and BaF2) were investigated by glancing angle X-ray diffraction (GAXRD), complemented by atomic force microscopy (AFM). Nano-grain fragmentation is observed with increasing ion fluences as evident from the increase of the peak width in GAXRD pattern. It is also observed that after certain fluence SHIs irradiation, there is a saturation in the nano-grain fragmentation. The track radius and damage cross section are deduced from peak width and area of the dominant diffraction. The track radii are 5.5 and 14.5 nm, 5.0 and 9.7 nm and 5.5 and 6.5 nm for BaF2, LiF, CaF2, deduced from width and area, respectively. It is noteworthy that the track radius is found to be higher than the previously estimated from sputtering studies of LiF thin films. (C) 2016 Elsevier B.V. All rights reserved.