Synthesis and luminescence properties of color-tunable Dy³⁺-activated CaWO₄ phosphors

Color-tunable CaWO₄:xDy³⁺ phosphors were prepared via a simple conventional solid-state reaction and their luminescent properties were investigated as a function of Dy³⁺ ion concentration under 258 and 353 nm excitations. A gradual enhancement in the emission intensity was observed with the increment of Dy³⁺ ion concentration, reaching its maximum value when x = 0.05. The main reason for the concentration quenching of Dy³⁺ emission in CaWO₄ host lattice is due to the electric dipole-dipole interaction. The cathodoluminescence spectra, which were measured at different accelerating voltages and filament currents, were in consistent with the photoluminescence spectrum excited at 258 nm. Additionally, the emission color of CaWO₄:xDy³⁺ phosphors can be suitably tuned from blue to green, and finally to yellow by the modulation of excitation wavelength and Dy³⁺ ion concentration. Ultimately, these color-tunable phosphors may have potential applications in the fields of miniature color displays.