| In recent years, rare-earth doped upconversion phosphors have received much attention due to its important applications in optoelectronics, biophotonics, and other areas. The yttrium aluminum garnet (YAG) is a kind of material with stable physical and chemical properties, rare earth doped YAG as luminescent materials is also of concern.Ga3+, In3+ ions co-substituted for Al3+ ions and rare earth doped YAG phosphors have been prepared by means of co-precipitation method and sintered at 1000 ℃. Their crystal structure, luminescence properties and luminescence mechanism of phosphors were investigated by TGA, XRD, SEM, XPS and the photoluminescence decay curves.Gallium-substituted Cerium-doped yttrium aluminum garnet (YAGG:Ce3+) phosphors were produced. It can be observed that gallium ions doping does not cause any change of YAG phase. The excitation and emission are peaked at 450nm and 527nm respectively. The best doping concentration of gallium ions is 15%. With higher gallium ions doping concentration, the sample experiences a concentration quenching, the crystallinity and luminescence intensity are reduced. When Ga3+ substitutes Al3+ ions in YAG matrix, a blue shift can be seen in emission spectrum.As upconversion phosphors Gallium-Indium co-substituted yttrium aluminum garnet (Er3+/Yb3+:YAG) phosphors were synthesized. Gallium and indium ions co-doping also did not influence the YAG phase. Under a 980nm laser excitation, two emissions located at 543nm and 662nm have been observed. The substitution of Al by Ga and In leads to blue shift emission, and the emission intensity increased with increasing indium concentration. Fluorescence lifetime measurement shows that the adulteration of Ga3+ and In3+ effects energy transfer between Yb3+ and Er3+ in the YAG simple.Moreover, Gallium-Indium co-substituted (Ho3+/Yb3+:YAG) phosphors were prepared by the same method. There is also no YAG phase change. Under the 980nm laser excitation, the green and red light emission wavelengths of fluorescent powder are located on 549nm and 659nm. With the increment of Ga3+ concentration, the shape of simple emission peak is not changed, relative luminescence intensity increase to a certain extent weakened. When the doping concentration of Ga3+ is 15%, the relative luminescence intensity reached the maximum.Gallium-Indium co-substituted yttrium aluminum garnet (Tm3+/Yb3+:YAG) phosphors were composited. It can be inspected that gallium and indium ions co-doping do not arouse the change of YAG phase. Under the 980nm laser excitation, the blue and red light emission wavelengths of fluorescent powder are located on 475nm and 650nm. With the increment of In3+ concentration, the shape of simple emission peak is not changed, relative luminescence intensity increase to a certain extent weakened. When the doping concentration of In3+ is 15%, the relative luminescence intensity reached the maximum. In the fluorescence lifetime figure, the adulteration of Ga3+ and In3+ has a certain influence on energy transfer between Yb3+ and Tm3+ in the YAG simple.The chemical co-precipitation method has high purity powder, good chemical homogeneity and other advantages. In this paper, a series of Gallium-Indium displaced yttrium aluminum garnet phosphors were composited by a co-precipitation method at a temperature of 1000℃. By analyzing weightlessness change to research the synthesis process of phosphor, the sample heated reaction at the temperature of 245 ℃, and then gradually in the crystallization after 500 ℃. The structure tests show that Ga and In replacing Al does not affect the formation of YAG phase in the matrix. Compared with the corresponding rare earth YAG, Ga and In replacing Al does not change emission peak, and the emission intensity increased with the concentration of gallium and indium increases. Phosphor at 980nm laser excitation achieve upconversion, the emission spectrum blue shift, and obtain the suitable co-doped amount, the relative luminous intensity is maximum at this point. |
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