UPCONVERSION LUMINESCENCE PROPERTIES OF Ho3+/Tm3+/Yb3+CO-DOPED NaGd(MO4)2 PREPARED BY HYDROTHERMAL METHOD

In this paper, Ho3+/Tm3+/Yb3+-doped NaGd(MO4)2 phosphors were prepared using the hydrothermal method and the effect of Yb3+ doping amount on the luminescence properties of these phosphor materials was investigated. NaGd(MO4)2 was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectral analysis. The results showed that Ho3+/Tm3+/Yb3+-doped NaGd(MO4)2 has tetragonal phase structures, and doping with rare-earth ions decreases the cell parameters of NaGd(MO4)2. NaGd(MO4)2:Ho3/Tm3+/Yb3+ generates blue, green, and red lights at 477, 545, and 659 nm, respectively, under an excitation of 980 nm. The emission of these three lights is called a three-photon process. As the doping ratio of Yb3+ increases, the colour coordinates of samples gradually approach the white region from the red region, enabling NaGd(MO4)2:0.1Ho/1Tm/20Yb to exhibit white emission. Doping with Yb3+ increases the energy transfer and quantum efficiencies of NaGd(MO4)2. When the concentration of Yb3+ reached 30%, the quantum efficiency of NaGd(MO4)2 reached the maximum value of 188.37%. Overall, NaGd(MO4)2:Ho/Tm/Yb has broad application prospects in the field of white lighting.