The order‐disorder phase transformation in ion‐irradiated rare earth sesquioxide Dy2O3

Abstract

AbstractIn this report, we examine an irradiation‐induced order‐disorder phase transformation in polycrystalline pellets of the rare earth sesquioxide Dy2O3 using grazing incidence X‐ray diffraction (GIXRD) and transmission electron microscopy (TEM). This sesquioxide is characterized by a cubic C ‐type rare earth structure known as bixbyite. Samples were irradiated with heavy ion Kr++ (300 keV) at cryogenic temperature. GIXRD and cross‐sectional TEM observations reveal that the ordered body‐centered cubic bixbyite structure transforms to a disordered (anion deficient) fluorite structure in this irradiated sesquioxide. This observation is consistent with a radiation‐induced disordering process in which the oxygen superlattice associated with the bixbyite structure is destroyed and the material adopts an anion disordered fluorite structure as evidenced by the disappearance of characteristic GIXRD diffraction peaks resulting from ordering of the oxygen superlattice, and similar electron diffraction pattern features. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)