Structural and Enhanced Optical Properties of Stabilized γ‒Bi₂O₃ Nanoparticles: Effect of Oxygen Ion Vacancies

We report the synthesis of room temperature (RT) stabilized γ-Bi₂O₃ nanoparticles (NPs) at the expense of metallic Bi NPs through annealing in an ambient atmosphere. RT stability of the metastable γ-Bi₂O₃ NPs is confirmed using synchrotron radiation powder X-ray diffraction and Raman spectroscopy. γ-Bi₂O₃ NPs exhibited a strong red-band emission peaking at ~701 nm, covering 81% integrated intensity of photoluminescence spectra. Our findings suggest that the RT stabilization and enhanced red-band emission of γ‒Bi₂O₃ is mediated by excess oxygen ion vacancies generated at the octahedral O(2) sites during the annealing process.