Photoluminescence Spectroscopy and First-Principle Calculation of Electronic Structure of Ce³⁺-Doped GdBO₃ Inorganic Nanoscintillator Material

Intense UV emission is observed in Ce³⁺-doped GdBO₃ nanophosphor, successfully prepared by simple sol gel method. The synthetized nano-powder sample is characterized by diffractometry (XRD) and room temperature steady photoluminescence. The XRD analysis shows that the crystallite size is 55 nm and crystallizes in the vaterite structure. The room temperature excitation and emission observed bands are assigned to 4f ↔ 5d inter-configurational transitions and investigated. First principal Density Functional theory DFT + U calculations, implemented in VASP code was used to performed the study of the structural and electronic structure of GdBO₃:Ce³⁺ nanomaterial system in both vaterite P63/mmc and calcite R-3C. The U parameter is varied to give best 4f Ce position in GdBO₃ bandgap. Also, it was found that the R-3C is the ground state crystalline structure and that the observed P63/mmc is higher in energy by about 0.1 eV/atom. By comparison between experimental and calculations results energy Ce³⁺ energy levels scheme relative to electronic band structure was constructed.