Lanthanide 4f energy levels in perovskite-type YAlO3

Based on experimental data, an energy diagram of 4f levels of lanthanide ions in perovskite-type YAlO3 was made to obtain fundamental knowledge of luminescence in trivalent lanthanide ions (Ln3+) doped YAlO3, YAlO3:Ln3+. Energy of valence band maximum (VBM) in YAlO3 and energies of Ln3+ 4f ground levels from VBM were determined by X-ray photoelectron spectra of non-doped YAlO3 and YAlO3:Ln3+ (Ln=Pr, Eu, Gd, Tb, Lu). Energies of Ln3+ 5d band were determined from the energy position of each photoluminescence excitation (PLE) peak attributed to 4f-5d transition. Energies of 4f ground levels of divalent lanthanide ions (Ln2+) were determined from the PLE peak of Eu3+ charge transfer states. Ln3+ 4f ground/excited levels, Ln2+ 4f ground levels, Ln3+ 5d bands, VBM and conduction band minimum were exhibited in the energy diagram setting the VBM at 0 eV. Luminescence of several YAlO3:Ln3+ was discussed referring to the diagram.