Swift heavy ion-induced phase transformation in Gd2O3

Crystalline-to-crystalline phase transformation of cubic Gd2O3 induced by swift Au ions with a kinetic energy of 2.25 GeV, has been characterized by synchrotron X-ray diffraction experiments (XRD) as a function of increasing fluence, up to 5 × 1013 ions/cm2. The diffraction maxima of the initial cubic structure gradually decrease in intensity as function of ion fluence, concurrent with the in-growth of several new diffraction peaks, which, based on Rietveld refinement, correspond to the monoclinic high-temperature phase. The same cubic-to-monoclinic phase transformation induced by swift heavy ions has been observed in Y2O3. The transformation pathway under irradiation is consistent with the high-temperature behavior of Gd2O3, and is probably associated with a multiple ion-impact mechanism. There was no evidence of amorphous material in the diffraction patterns, even after irradiation to the maximum fluence, at which the initial cubic phase has been completely transformed to the monoclinic structure.