Novel Mn4+-activated oxyfluoride Cs2NbOF5:Mn4+ red phosphor for warm white light-emitting diodes

Novel red-emitting phosphor Cs2NbOF5:Mn4+ was prepared via the ion exchange method, and its crystal structure, composition and morphology were characterized by powder X-ray diffraction, energy-dispersive X-ray spectroscopy and scanning electron microscopy. Meanwhile, the influence of Mn4+ molar ratio on luminescence properties of Cs2NbOF5:Mn4+ has been investigated. The phosphor prepared with the Nb2O5/K2MnF6 molar ratio of 20:1 can emit intense red light under blue light excitation and improve the performances of white light emitting diode with high color rendering index of 88.4 and low correlated color temperature of 3631 K, so this new red-emitting phosphor could find application on solid-state emitting diode.