SWIFT-URANIUM-ION-INDUCED DAMAGE IN SAPPHIRE

Single crystals of α-Al2O3 were irradiated at Ganil with U238 ions using four different energies: 0.48, 1.72, 2.78, and 3.40 MeV/u. All the irradiations were performed at a temperature of 80 K, with fluences extending from 1.2×1012 to 2.5×1012 ions cm-2. The samples were characterized by Rutherford backscattering spectrometry in channeling geometry (RBS-C) and optical absorption measurements. RBS-C analyses evidence the lattice disorder induced by collective electronic excitations. Depending on the electronic stopping power (dE/dx)e (up to 44.2 keV nm-1), the damage cross section Ae varies between 0.3 and 2.1×10-13 cm2. Optical absorption spectroscopy exhibited the characteristic bands associated with oxygen vacancies. The kinetics of F centers were determined in order to precisely determine the respective contributions of the nuclear and electronic processes in point-defect generation. © 1995 The American Physical Society.