Photoluminescent characterization of KNbO3:Eu3+

In this study, the photoluminescence (PL) spectra of europium-doped potassium niobate (KNbO3) crystallites prepared by a vibrating milled solid-state reaction method were studied. X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical spectral analysis (luminescence excitation, emission spectra and time-resolved spectra) were used to characterize the KNbO3:Eu3+ powders. The results of the XRD revealed that the powders remained as a single orthorhombic structure at doping concentrations below 3 mol%. A second phase of EuNbO4 begins to appear at 5 mol%. The 5D0–7F1 (593 nm) and 5D0–7F2 (614 nm) emission characteristics of Eu3+ appear at a quenching concentration of above 3 mol%. The Commission Internationale d’Eclairage (CIE) chromaticity coordinates of a Eu:KNbO3 host excited at λex = 400 nm and λex = 466 nm wavelengths, both presented a red-shift when increasing the Eu3+ ion doping. The lifetime of the Eu3+ ion decreased as the doping concentration was increased from 1 to 7 mol%.