Hydrothermal synthesis and multicolor luminescence properties of Dy3+/Eu3+ co-doped KLa(MoO4)2 phosphors

Abstract

A series of Dy3+/Eu3+ co-doped KLa(MoO4)2 phosphors were synthesized by a hydrothermal method. The as-prepared samples were characterized by an X-ray diffraction (XRD), a field emission scanning electron microscope (FE-SEM), a photoluminescence (PL) excitation, emission spectra and decay curves. The samples have a single-phase monoclinic structure of KLa(MoO4)2 and consist of microspheres with the mean size of 1.5μm. Upon excitation at 389nm, KLa(MoO4)2:Dy3+ exhibits characteristic peaks at 485nm and 576nm. The optimal doping concentration of Dy3+ is about 7mol%. KLa0.93−y(MoO4)2:0.07Dy3+, yEu3+ samples show emission peaks of both Dy3+ and Eu3+ centered at 485, 576, 595 and 618nm under 389nm excitation. It can be found that the integrated emission intensity of Dy3+ is decreased and the lifetime of Dy3+ is declined with increasing Eu3+ concentration, which is due to the energy transfer from Dy3+ to Eu3+. Furthermore, according to Dexter's theory and Reisfeld's approximation, the quadrupole–quadrupole (q–q) interaction is the mechanism for energy transfer between Dy3+ and Eu3+. Moreover, the chromaticity color coordinates of KLa0.93−y(MoO4)2:0.07Dy3+, yEu3+ samples are tuned from the yellowish-white region to white light and eventually to the reddish-white region with increasing Eu3+ content. This kind of multicolor tunable phosphors exhibits the great potential applications in the fields of white light diodes, full-color displays and optoelectronic devices.