[Effects of Zn2+ doping on the structural and luminescent properties of GdTaO4 : Eu3+ phosphors]

GdTaO4 : Eu0.1 phosphors with different concentrations of Zn2+ dopant were synthesized by the solid-state reaction at high temperature. The present paper mainly focused on the effects of Zn2+ on the crystallization behavior, morphology and photoluminescence (PL) properties of GdTaO4 : Eu3+. The synthesized materials were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), PL excitation and emission spectra, decay time curves, etc. Results suggested that the co-doping of Zn2+ could remarkably improve the PL intensity of GdTaO4 : Eu0.1, and there were two maxima in the curve of Eu3+ PL intensity at 611 nm vs Zn2+ doping concentration x. When x = 0. 01 the intensity was improved up to 2.7 times that of pure GdTaO4 : Eu3+, which could be attributed to the creation of oxygen vacancies for the charge neutrality and the alternation of the local environment of activator Eu3+ ions resulting from the incorporation of Zn2+ ions; the other was enhanced up to 3.2 times at x = 0.13 which was due to the flux effect of Zn2+ ions. But ZnO and GdTa7O19 were observed in an excessive Zn2+ doping range (x > 0.13), which resulted in the decrease in the PL brightness and lengthening of decay time. Meanwhile, primary results indicated that the PL intensity of GdTaO4 : Eu0.1, Zn0.13 could be further strengthened by the co-doping of Li+ and K+ ions.