Radiation damage induced by swift heavy ions and reactor neutrons in Y 3Al 5O 12 single crystals

Abstract

The induced damage in single crystals of Yttrium aluminium garnet (Y 3Al 5O 12) bombarded at GANIL with 561 MeV 51Cr, 466 MeV 128Te, 880 and 957 MeV 208 Pb and 885 MeV 238U ion beams, and at Algiers with reactor neutrons has been studied by optical measurements, profilometry and X-ray diffraction techniques (XRD). The optical absorption spectrum increases with fluence up to saturation level and absorption bands at about 250, 300, and 380 are observed after irradiation with ions and neutrons. X-ray diffraction as well as profilometry measurements show the volume expansion of the sample after irradiation due to the phase transformation from crystalline to amorphous phase. This volume expansion increases as a function of fluence and mean electronic stopping power S e. It reaches saturation at high fluence, but the evolution with S e shows a maximum at 17 keV/nm then it decreases significantly at 31 keV/nm. The track radii deduced from these techniques is seen to increase as a function of mean electronic stopping power from 8 to 17 keV/nm. From the analysis of the results, it is clear that the color centres do not contribute significantly to the swelling in the case of heavier ions with S e larger than 12 keV/nm.