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On the defect pattern evolution in sapphire irradiated by swift ions in a broad fluence range |
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| Authors: | P.M. Gordo,L. Liszkay,K. Havancsá k,G. Kö gel,W. Egger,M.F. Ferreira Marques |
| Affiliation: | a ICEMS, Department of Physics, University of Coimbra, P-3004-516 Coimbra, Portugal b KFKI Research Institute for Particle and Nuclear Physics, P.O. Box 49, H-1525 Budapest 114, Hungary c Department of Materials Physics, Eötvös University, Pázmány Péter sétány 1A, H-1117 Budapest, Hungary d Flerov Laboratory of Nuclear Reactions, Center of Applied Physics, JINR, 141980 Dubna, Russia e Institut für Angewandte Physik und Messtechnik LRT2, Fakultät für Luft- und Raumfahrttechnik Werner-Heisenberg-Weg 39, D-85577 Neubiberg, Germany f Instituto Superior Engenharia, P-3031-199 Coimbra, Portugal |
| Abstract: | Sapphire samples, irradiated with swift Kr (245 MeV) ions at room temperature in a broad fluence range, were investigated using a continuous and a pulsed positron beam to study the defect structure created by the passage of the ions in depths of a few micrometers. At small doses, monovacancies were identified as dominant defects and positron trapping centres. These monovacancies are assumed to be highly concentrated inside a cylindrical volume around the ion path with an estimated radius of ∼1.5 nm. For higher doses a second type of trapping centre emerges. This second class of structural imperfection was associated with the overlap of the individual ion tracks leading to the formation of larger vacancy clusters or voids. |
| Keywords: | Sapphire Al2O3 Positron lifetimes Doppler broadening Defects Positron trapping |
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