Abstract: A series of Eu³⁺ doped and Li⁺, Eu³⁺ co-doped Gd₂ZnTiO₆ (GZT) red-emitting phosphors were successfully prepared by sol-gel method. The effects of Li⁺ and Eu³⁺ ions doping on the crystal structure, microstructure and luminescent properties of the samples were studied. Results show that the obtained double perovskite Gd₂ZnTiO ₆∶Li⁺,Eu³⁺(GZT∶Li⁺,Eu³⁺) phosphors crystallized in the monoclinic space group P2₁/n and are composed of irregular particles with the size of 10 μm. Under the excitation of 395 nm near ultraviolet light, the emission spectrum of GZT∶Eu³⁺ shows a typical linear characteristic spectrum of Eu³⁺ ions. The center position of the emission peak is located at 615 nm, which belongs to the ⁵D₀→⁷F₂ transition of Eu³⁺. The optimum doping concentration of Eu³⁺ is 0.07 (mole fraction). The obtained samples show obvious concentration quenching effect, and its mechanism can be identified as the electric dipole-dipole interactions(d-d). In addition, it is also found that Li⁺ doping has no effect on the crystal structure and micro morphology of the samples, but a certain amount of Li⁺ doping can significantly enhance the fluorescence intensity of the samples. When the concentration of Li⁺ is 0.05, the intensity of the main emission peak of the phosphor is the largest, which is 4.3 times of the original, indicating that high brightness GZT red-emitting phosphor can be obtained by co-doping Li⁺ and Eu³⁺. The CIE color coordinates of GZT∶0.14Eu³⁺,0.05Li⁺ phosphor is located at (0.631 1,0.375 3) close to the standard red color coordinates (0.670, 0.330), which is a potential red-emitting phosphor for LED.

Key words: Gd₂ZnTiO₆, sol-gel method, Li⁺, Eu³⁺ co-doping, double perovskite, red-emitting phosphor