Control of Luminescence by Tuning of Crystal Symmetry and Local Structure in Mn4+-activated Narrow Band Fluoride Phosphors
M.-H. Fang, W.-L. Wu, Y. Jin, T. Lesniewski, S. Mahlik, M. Grinberg, M. G. Brik, A. M. Srivastava, C.-Y. Chiang, W. Zhou, D. Jeong, S. H. Kim, G.
2018/03/01
Mn4+-doped fluoride phosphors have been widely used in wide-gamut backlighting devices because of their extremely narrow emission band. Solid solutions of Na2(SixGe1−x)F6:Mn4+ and Na2(GeyTi1−y)F6:Mn4+ were successfully synthesized to elucidate the behavior of the zero-phonon line (ZPL) in different structures. The ratio between ZPL and the highest emission intensity υ6 phonon sideband exhibits a strong relationship with luminescent decay rate. First-principles calculations are conducted to model the variation in the structural and electronic properties of the prepared solid solutions as a function of the composition. To compensate for the limitations of the Rietveld refinement, electron paramagnetic resonance and high-resolution steady-state emission spectra are used to confirm the diverse local environment for Mn4+ in the structure. Finally, the spectral luminous efficacy of radiation (LER) is used to reveal the important role of ZPL in practical applications.
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