First Report of Energy Transfer from Uranyl to Mn4+ in K3(UO2)F5:Mn4+

Abstract This work relates to the synthesis and optical characterization of a novel Mn4+ activated luminescent material with the composition K3(UO2)F5:Mn4+. This is the first report of a Mn4+ activated compound comprising the uranyl cation UO22+. A highly efficient energy transfer from uranyl to Mn4+ is observed, which enables the phosphor to be excited in a broad spectral range with a large absorption cross section. Simulated spectra show that the phosphor is suitable for use in full-conversion (In,Ga)N LEDs for high color rendering index/high luminous efficacy applications. The ratio between the emission of uranyl and Mn4+ exhibits a strong temperature dependence which is linked to an underlying phonon-assisted energy transfer.