In Situ Localized Transformation from Anatase to Titanium Monoxide via Focused Electron Beam Irradiation

Precise architectural control of nanocrystals is essential for engineering functional nanomaterials, where electron beam processing offers unique capabilities in top-down nanofabrication. Achieving spatially targeted nanostructure via electron beam manipulation remains technologically challenging. This study demonstrates localized reductive transformation from TiO₂ to conductive TiO within 5 nm regions, accomplished through controlled electron probe irradiation in an aberration-corrected transmission electron microscope. In situ electron energy-loss spectroscopy and electron beam-mass spectroscopy confirm thickness reduction, electronic structure transformation, and Ti and O₂ (O) generation during reaction. The dose limitation for the reductive transformation is quantitatively analysed. Induced electric field caused by the ionization via electron-atom inelastic scattering is demonstrated as the mechanism for the reductive transformation. These findings provide a methodology for introducing TiO conductive channels in TiO₂-based devices through controlled electron beam processing. The demonstrated precision in phase engineering advances functional nanodevice fabrication with atomic-scale accuracy, offering critical insights for tailoring material properties in practical applications.