Radioluminescence mechanism and hierarchical dopant effects in LiMgPO 4 :Tb,Sm,B

This work presents a systematic radioluminescence (RL) spectroscopic study of LiMgPO4 triply doped with Tb, Sm and B to elucidate the hierarchical roles of dopants and validating a unified energy transfer model that bridges RL and thermoluminescence (TL). Through comparative analysis of single-, double- and triple-doped samples, it is demonstrated that Tb3+ serves as the primary luminescence center, characterized by its dominant 5D4 → 7F6 transition at ∼550 nm. Sm3+ acts as a secondary emitter and, more importantly, as a sensitizer that enhances Tb3+ luminescence without forming new emission bands in the triple-doped system. Boron (B3+) functions as an efficient sensitizer that preferentially boosts the intrinsic host emission at ∼350 nm and also enhances activator emissions, with the optimal concentration identified as 4 mol%. Most critically, direct comparison between RL and TL spectra reveals complete spectral correspondence – all major RL emission peaks (Tb3+: ∼550 nm; Sm3+: ∼608, 656 nm; host: ∼350 nm) are identically reproduced in the TL emission spectrum recorded at 250 °C. This consistency provides unambiguous evidence that the same luminescent centers (Tb3+, Sm3+ and host defects) govern both prompt RL and trap-mediated TL processes, thereby validating the ‘center-to-center’ energy transfer model previously proposed for this material. Concentration optimization experiments show that the maximum RL intensity is achieved at Tb = 0.5 mol%, Sm = 0.3 mol% and B = 4 mol%. The observed dopant hierarchy and spectral unification not only advance the fundamental understanding of rare-earth interactions in phosphate hosts but also offer practical guidelines for designing high-performance dosimetric materials for real-time radiation monitoring and cumulative dose assessment, with potential applications in medical dosimetry, environmental radiation surveillance and nuclear accident personal dose evaluation.Highlights Hierarchical dopant functions in LiMgPO4:Tb,Sm,B are established.Complete spectral correspondence between RL and TL emissions is identified. The center-to-center energy transfer model in triply-doped phosphate is validated.Tb3+ concentration quenching and Tb3+→Sm3+ energy transfer are elucidated.B3+ modulates host emission without creating new luminescent centers.