Control of luminescence by tuning of crystal symmetry and local structure in Mn4+-activated narrow band fluoride phosphors

This work was supported by the Ministry of Science and Technology of Taiwan (Contract Nos. MOST 104-2113-M-002-012-MY3 and MOST 104-2923-M-002-007-MY3) and National Center for Research and Development Poland Grant (No. PL-TW2/8/2015). Y Jin thanks the National Nature Science Foundation of China (No. 11104366), Chongqing Research Program of Basic Research and Frontier Technology (No. cstc2014jcyjA50018), and the Scientific and Technological Research Program of Chongqing Municipal Education Commission (No. KJ1500913). T. Lesniewski would like to acknowledge the support of University of Gdansk Research Grant 538-5200-B468-17.Mn4+-doped fluoride phosphors have been widely used in wide-gamut backlighting devices because of their extremely narrow emission band. In this study, solid solutions of Na2(SixGe1-x)F6:Mn4+ and Na2(GeyTigros)F6:Mn4+ have been successfully synthesized to elucidate the behavior of zero-phonon line (ZPL) in different structures because of the sensitivity of ZPL intensity to the local coordinated environment. The structures of the products are examined by X-ray diffraction and Rietveld refinement. 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. The calculated results are consistent with the experimentally determined structural parameters. To compensate for the limitations of Rietveld refinement, electron paramagnetic resonance and high-resolution steady-state emission spectra are used to prove 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 application.PostprintPeer reviewe