X-ray Spectroscopic Study on Photoluminescence Properties of Red Phosphor SrTiO3:Pr3+,Al

Abstract

The electronic structure of the practical red phosphor SrTiO₃;Pr³⁺,Al is studied by X-ray absorption and emission spectroscopy under ultraviolet (UV) irradiation. In contrast to the invariance of the oxygen Kα emission spectra, the titanium K-edge absorption spectra show two characteristic changes depending on UV energy, one of which is proportional to the photoluminescence excitation spectrum while the other is insensitive to it. With these results, a schematic energy diagram is proposed where the titanium 4p band pulled down by oxygen valence holes overlaps Pf 4f radiative centers situated just below the conduction band. The photoluminescence properties are briefly discussed in relation to the ferroelectric phase transition from an electronic viewpoint.