Preparation, Energy Transfer Characteristics and Colorimetric Properties of Na2Dy4(WO4)7:Eu3+ Nanophosphors

Eu3+-doped Na2Dy4(WO4), nanophosphors were synthesized via a co-precipitation method. The crystal structure and morphology of the nanophosphors were characterized by X-ray diffraction analysis and field emission scanning electron microscopy, respectively. For all Eu3+ doping concentrations, spherical particles with an average diameter of about 40 nm and consisting of a pure Na2Dy4(WO4)(7) phase were obtained. The excitation and emission properties of the nanophosphors were examined by fluorescence spectroscopy and the energy transfer between Eu3+ and Dy3+ was studied. Furthermore, the influence of the Eu3+ concentration on the color coordinates and luminescence intensity is discussed. The nanophosphors could easily be excited by ultraviolet (UV) and near-UV light corresponding to the f-f transitions of Dy3+. The color coordinates of the nanophosphors light emission are in the white light region and the Commission Internationale de l'Eclairage (CIE) coordinates of the nanophosphors light emission varied between (0.331, 0.354) and (0.405, 0.368) depending on the Eu3+ doping concentration.