Structure and chemical changes of CeO 2 irradiated with hydrogen ions

Abstract

Thin film specimens of CeO 2 were irradiated with 10 keV hydrogen (H) ions at room temperature in an ion-implanter-interfaced transmission electron microscope (TEM) to doses up to 5×10 20 ions m −2 in order to study the defect evolution of the material under ion irradiation. The structure and chemical state changes were investigated using an analytical TEM. After the H + irradiation, CeO 2 specimens showed changes in both the structure and electron energy loss spectroscopy (EELS) spectra of O–K and Ce–M edges. Stacking faults with sizes from several nanometers to several tens of nanometers were observed in specimens irradiated to a dose of 5×10 19 ions m −2. The change in EELS spectra of O–K edge was much more obvious than that of Ce–M edge. Oxygen-related point defects are considered to be produced much more than those of cerium-related point defects in the H + irradiated specimens. The difference in point defect production for oxygen-related ones and cerium-related ones are suggested to be an important factor to influence the evolution of both the structure changes and chemical state changes in the H + irradiated CeO 2.