Initial stages of ion beam-induced phase transformations in Gd_2O_3 and Lu_2O_3

摘要

The atomic-scale evolution of lanthanide sesquioxides Gd2O3 and Lu2O3 irradiated with 1MeV Kr ions at room temperature and 120 K, up to fluences of 1 x 10(16) ions/cm(2) (similar to 20 dpa), has been characterized by in situ transmission electron microscopy. At room temperature, both oxides exhibited high radiation tolerance. Irradiation did not cause any observable structural change in either material, likely due to the mobility of irradiation-induced point defects, causing efficient defect annihilation. For Gd2O3, having the larger cation ionic radius of the two materials, an irradiation-induced stacking fault structure appeared at low fluences in the low temperature irradiation. As compared with the cubic-to-monoclinic phase transformations known to result from higher energy (similar to GeV) ion irradiation, Kr ions of lower energies (similar to MeV) yield much lower rates of damage accumulation and thus less extensive structural modification. At a fluence of 2.5 x 10(15) ions/cm(2), only the initial stages of the cubic-to-monoclinic (C to B) phase transformation process, consisting of the formation and aggregation of defects, have been observed. Published by AIP Publishing.