Inductive effect of cationic equivalent substitution tuning europium valence in Na2Zr1-xHfxSiO5:Eu phosphors for WLEDs

The realization of Eu 3+ reduction and its reduction mechanism have become focal points in the field of WLED phosphor research. In this study, the reduction of Eu 3+ was successfully achieved through cationic substitution strategy by replacing Zr 4+ with Hf 4+ in Na 2 ZrSiO 5 :Eu 3+ . The effects of substituting Hf 4+ for Zr 4+ on the phase, crystal structure, and luminescence properties of Na 2 Zr 1- x Hf x SiO 5 :Eu 0.03 (0 ≤ x ≤ 1) were thoroughly investigated based on Rietveld refinement , spectral data, DFT calculation and electronegativity of ions. Comprehensive consideration was given to the effect of site size change and site reducibility on Eu 3+ reduction. The results demonstrate that the reduction of Eu 3+ in Na 2 Zr 1- x Hf x SiO 5 :Eu 0.03 is attributed to the alteration in inducible effect caused by cationic substitution and the enhancement in site reducibility rather than changes in site size. Therefore, the cationic substitution strategy based on induction effect presents a novel approach for achieving Eu 3+ reduction and offers a new insight into developing and modifying Eu 2+ -activated phosphors.