Out-of-plane swelling of gadolinium gallium garnet induced by swift heavy ions

Single crystals of gadolinium gallium garnet (Gd3Ga5O12) have been irradiat ed with various ions (Cr 10.6 MeV/u, Cu 0.8 MeV/u, Kr 9 MeV/u, and Pb 4 MeV /u) in the electronic stopping power regime. The irradiated areas of the cr ystals exhibited a pronounced volume expansion. Using a profilometer, the o ut-of-plane swelling was measured by scanning over the border line between an irradiated and virgin area of the sample surface. The step height varied between 25 and 160 nm depending on the fluence, the electronic stopping po wer and the total range of the ions. In the high fluence regime, the swelli ng effect approaches saturation. In order to compare the results obtained f or different ion species, the initial swelling per ion was normalised by th e length of the damage track. Such an analysis makes evident that swelling occurs only above a critical energy loss of 7 +/- 2 keV/nm. The results of Gd3Ga5O12 will be compared with data obtained earlier in SiO2 and LiNbO3. ( C) 1998 Elsevier Science B.V. All rights reserved.