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Angle dependent threshold for swift heavy ion track formation in SrTiO_3

The recent discovery of multiple, equally spaced nanodots created on the surface of strontium titanate when irradiated by swift heavy ions under the grazing incidence [1] has generated considerable interest in studying detailed morphology of ion tracks. After the further AFM investigations of samples irradiated at the lower ion energies [2], the threshold for surface ion track formation has been determined to be between 5 - 7 keV/nm and the evolution of ion track radii with stopping power was described. TEM investigation of ion tracks in the bulk material [2] yielded threshold at 7 keV/nm for amorphisation. At lower projectile velocities, SrTiO3 remained single crystalline, thus nuclear stopping could be excluded as an origin of this damage. However, threshold for swift heavy ion track formation and track morphology in the bulk SrTiO3 remained uncertain. In order to gain better understanding of ion track formation in the bulk SrTiO3, channeling RBS measurements were performed on samples irradiated with iodine ions in the 18 - 34 MeV energy range. It was found that formation of ion tracks depends not only on stopping power value, but also on the angle of irradiation with respect to the crystallographic axes. New model developed on the thermal spike basis provides explanation for this behavior and relates it to the ion track morphology. [1] E. Akcöltekin et al., Nat. nanotechnol. 2 (2007) 290 [2] M. Karlušić et al., New J. Phys. 12 (2010) 043009

ion track; SrTiO_3

Posteru je dodijeljena nargada "E-MRS Graduate Student Award"