نبذة مختصرة : International audience ; Swift Heavy Ion (SHI) irradiation offers a powerful approach for tailoring structural and chemical properties of materials through precise energy deposition mechanisms. This study explores nanoscale structural and chemical transformations induced by SHI irradiation in SrTiO 3 (STO) thin films. A 20 nm STO layer, grown on a Si (001) substrate by molecular beam epitaxy, is irradiated with 71 MeV 129 Xe 19+ ions at a grazing incidence angle of 3°. Atomic force microscopy and reflection high‐energy electron diffraction reveal the formation of amorphous nanohillocks aligned with the ion tracks, exhibiting increased roughness with nanoscale ion tracks forming a ripple pattern. High‐resolution scanning transmission electron microscopy combined with electron energy loss spectroscopy identifies structural phase separation within the hillocks, characterized by SrO and TiO x segregation, along with compositional shifts, including Sr depletion and localized oxygen deficiency. Analyses of the fine structures of Ti L 2,3 and O K edges highlight oxygen vacancies and the partial reduction of Ti 4+ to Ti 3+ in the hillocks. These findings provide critical insights into the mechanisms of SHI‐induced structural and chemical modifications, with potential implications for defect engineering and nanostructuring in oxide materials.
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