On the Luminescent Properties of Eu ³⁺ ‐Doped La ₂ M ₃ (MoO ₄ ) ₉ (M = Hf, Zr)

Eu 3+ ‐doped double molybdates La 2− x Eu x M 3 (MoO 4 ) 9 (M = Hf, Zr) are synthesized via solid‐state reaction and systematically investigated with respect to their structural and luminescent properties under ultraviolet, vacuum ultraviolet, and X‐ray excitation. X‐ray diffraction confirms phase purity and full solid solution formation up to 20 mol% Eu 3+ . Both materials exhibit strong red emission dominated by the hypersensitive 5 D 0 → 7 F 2 transition, with minimal concentration quenching observed in the hafnate system. Excitation‐dependent emission and decay analyses reveal efficient energy transfer to Eu 3+ , monoexponential decay behavior, and long lifetimes (≈1250 µs), indicating minimal nonradiative losses. Spectral red shifts of the charge transfer band with increasing Eu 3+ content and variation in host cation (Zr vs Hf) are attributed to changes in local coordination and electronic structure. Commission internationale de l’eclairage (CIE) chromaticity coordinates and luminous efficacy data confirm highly saturated red emission and excellent performance, particularly for La 2− x Eu x Hf 3 (MoO 4 ) 9 , making it a promising red phosphor for high‐energy excitation environments.