Investigations on ion irradiation induced microstructural changes in Gd2O3 nanorods.

Ion irradiation induced phase transformations in Gd 2 O 3 nanorods dispersed on TEM grids, are investigated using synchrotron X-ray diffraction and transmission electron microscopy. Ion irradiation induced cubic (C) to monoclinic (B) phase transformation is observed in Gd 2 O 3 nanorods. Gd 2 O 3 nanorods are partially transformed to monoclinic phase at 0.63 dpa (5 × 1016 ions/cm2) itself. The C→B phase transformation is reconstructive type transformation where the role of O-vacancies and diffusion are very important. During He+ ion irradiation, the displacement cascades produced O-vacancies and during the non-melting thermal spike regime, diffusion was assisted and it resulted in the phase transformation. In addition to phase transformation, TEM investigations shows formation of amorphous carbon layer around the nanorods and welding of the nanorods, upon ion irradiation. These observations are explained based on the mechanisms of GOLF (giant onion like fullerene) formation and the localized surface melting during thermal spike. • 100 keV He + ion induced cubic to monoclinic transformationobserved in Gd 2 O 3 nanorods. • O-vacancies produced by displacement cascades, and during the non-melting thermal spike regime, diffusion was assisted. • Vacancies and diffusion assists the C.→B phase transformation is reconstructive type phase transformation. • Synchrotron XRD is able to detect the small volume fraction of monoclinic phase. • The Gd 2 O 3 nanorods are found to be nanowelded upon ion irradiation. [ABSTRACT FROM AUTHOR]