TY  - JOUR
AU  - Halmurat, Dilare
AU  - Zhang, Xinyu
AU  - Aihaiti, Litipu
AU  - Xie, Rong-Jun
PY  - 2026
TI  - Narrowband green emission in CaF2: U6+ phosphors via dynamic F–O coordination and defect synergy
JO  - Journal of Materiomics
SN  - 2352-8478
VL  - 12
IS  - 3
AB  - This work breaks the long-standing confinement of uranium (Ⅵ) luminescence to octahedral oxides by demonstrating efficient narrowband green emission at 530 nm (FWHM = 25.7 nm) in eight-coordinate CaF2. This breakthrough is achieved through dynamic fluorine-oxygen coordination and defect synergy. Oxygen incorporation reconstructs [UOaF8–a] complexes via defect-mediated charge compensation, thereby resolving the fundamental mismatch between U6+ and Ca2+ sites. The optimally doped phosphor (0.1% (in mole) U6+) achieves a high internal quantum efficiency of 71.1% (EQE = 28.9%). Furthermore, spectral evolution reveals three Gaussian sub-bands, which are attributed to distinct Jahn-Teller distortions correlated with U–O bond contraction. Crucially, we establish a dual-channel oxygen-delivery mechanism via CaO co-addition, which synergistically enhances the emission intensity by 150% at 15% CaO loading while preserving a narrow bandwidth of 25–27 nm. Electron paramagnetic resonance spectroscopy confirms fluorine vacancies as the key charge compensators, validating the proposed enhancement mechanism from optimized [UOaF8–a] coordination and suppressed nonradiative pathways. Despite the extreme thermal quenching (only 7% intensity retention at 125 ℃) linked to F-vacancy phonon scattering, the ultra-narrow emission enables unique thermometric applications with a relative sensitivity of 0.4% K−1. This work ultimately establishes a paradigm of defect-mediated coordination engineering for activating multifunctional luminescence from lanthanides and actinides in non-traditional hosts.
UR  - https://doi.org/10.1016/j.jmat.2026.101185
DO  - 10.1016/j.jmat.2026.101185