Synthesis, electronic structure and luminescence properties of color-controllable Dy3+/Eu3+-codoped CaWO4 phosphors

Color-tunable CaWO4:0.05Dy3+/xEu3+ phosphors were synthesized via a solid-state reaction method and the electronic properties of CaWO4 host lattice were analyzed through density function theory calculation. Under the excitations of 250 and 351 nm, characteristic emissions corresponding to 5D0→4FJ (J=0, 1, 2) transitions of Eu3+ ions and characteristic blue and yellow emissions corresponding to 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions of Dy3+ ions, respectively, were observed in all the Dy3+/Eu3+ ions codoped CaWO4 phosphors. The photoluminescence spectra and decay curves revealed that there existed an energy transfer from Dy3+ to Eu3+ ions and this was certified to be a resonant type via a dipole-dipole interaction. Furthermore, color-tunable emissions were observed by adjusting the relative content between Dy3+ and Eu3+ ions and the excitation wavelength. In addition, the Dy3+/Eu3+ ions codoped CaWO4 phosphors exhibited strong cathodoluminescence properties and their emission intensity increased with the increment of accelerating voltage from 1 to 5 kV and filament current from 34 to 55 μA.