@article{Halmurat2026, 
author = {Dilare Halmurat and Xinyu Zhang and Litipu Aihaiti and Rong-Jun Xie},
title = {Narrowband green emission in CaF2: U6+ phosphors via dynamic F–O coordination and defect synergy},
year = {2026},
journal = {Journal of Materiomics},
volume = {12},
number = {3},
keywords = {Narrowband emission, Uranium (Ⅵ) luminescence, Dynamic coordination, Fluoride phosphors, Oxygen defect engineering, Thermal quenching},
url = {https://www.sciopen.com/article/10.1016/j.jmat.2026.101185},
doi = {10.1016/j.jmat.2026.101185},
abstract = {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.}
}