Luminescence spectra and site-occupation of Eu³⁺ centres in lithium antimonate LiSbO₃ lattice

It is a challenge to accurately determine the exact location of the rare earth ion (RE) in the lattice when there are significant differences in radius, electronegativity and valence between the lattice cation and the corresponding RE activator in a host material. This study presents the findings on the luminescence and site occupancy of Eu³⁺ emission centers in the lithium antimonate LiSbO₃ lattice. The phase-formation, structures, elemental composition, band transition characteristics, luminescence properties, and lifetimes of the Eu³⁺-doped phosphors were investigated. Eu³⁺-doped LiSbO₃ exhibits a typical ⁵D₀→⁷F₂ red luminescence transition at 613 nm. Site-selective excitation, luminescence, and decay properties at the ⁷F₀→⁵D₀ transition wavelength were measured using a tunable pulsed narrow-band dye laser. Two Eu³⁺ luminescence centers in LiSbO₃ were identified across the temperature range from 10 K to 300 K. The doping of RE(Eu³⁺) in LiSbO₃ consistently occupies two crystallographic positions of Li⁺ and Sb⁵⁺. Furthermore, the probability of RE(Eu³⁺) ions preferentially occupying the Li⁺ (M) sites is notably high. The decay curves and luminescence lifetimes of the two Eu³⁺ centers were determined. Drawing from the experimental data, we discuss the potential defects induced by Eu³⁺ doping in LiSbO₃ and the mechanism of charge compensation. These results could be instrumental in the advancement of new RE-activated luminescent materials or serve as a reference for investigating the specific positioning of RE ions within a phosphor lattice.