NaGdF4:Dy3+ nanocrystals: new insights on optical properties and energy transfer processes

NaGdF4:Dy3+ nanocrystals (NCs) have been synthesized by precipitation technique. The structural characteristics and morphology of the materials were analyzed via the measurements of X-ray diffractometer patterns and scanning electron microscope images, respectively. The photoluminescence excitation spectra, emission spectra and decay curves of all samples were recorded at room temperature. The color feature of the Dy3+ luminescence was estimated by CIE chromaticity coordinates and the correlated color temperature. The radiative properties of the Dy3+:4F9/2 level in material were analyzed within the framework of JO theory. In NaGdF4:Dy3+ NCs, the energy transfer from Gd3+ to Dy3+ causes the enhancement for the luminescence of the Dy3+ ions. The rate of the processes taking part in the depopulation of the Gd3+ was estimated. The energy transfer between Dy3+ ions leads to the luminescence quenching of NaGdF4:Dy3+. In this process, the dipole-dipole interaction, which is found by using the Inokuti-Hirayama model, is the dominant mechanism. The characteristic parameters of the energy transfer processes between Dy3+ ions have also been calculated in detail.