Structural Refinement, Core–Shell Electron Structure, Enhanced Phosphorescence, and Splitting of 5D0 → 7F2 Transitions in Li‑doped Rare Earth Oxide Systems

Abstract

Various concentrations of Lithium-Europium doped Gadolinium Oxide powders are synthesized by a high-temperature solid-state reaction method. X-ray diffraction pattern of the compounds revealed single-phase crystal formation, consistent with the predominant monoclinic phase of Gd2O3. The scanning electron micrographs and their analysis showcase dense growth of microparticles with average sizes ranging between 1.5 to 2 μm. The presence of constituent elements was identified using X-ray photoelectron spectroscopy. Eu3d, Li1s, Gd4d, and O1s, spectra were detected using the narrow scan spectra, and their deconvolutions of them show valance stability in the compound systems. Deep-level photoluminescence spectra showed enhanced multiple emissions in the orange-red region corresponding to transitions of 5D0-7F2, 5D0-7F1, and 5D0-7F0 arising from Lithium activator incorporation. Polarization anisotropy of the monoclinic structure of samples brought out interesting crystal field splitting in the pure electric dipole 5D0-7F2 transitions.