Preparation of Gd₂O₂S:Yb,Ho Phosphor via Thermolysis of Sulfur−Contained (Gd,Yb,Ho)S₂CN(C₄H₈)₃ Phen Complexes

A novel handy single-source precursor method is adopted to prepare Gd₂O₂S:Yb,Ho up−conversion phosphors. Pure Gd₂O₂S:Yb_0.06Ho_0.02 phosphors are prepared via thermolysis of the air−stable ternary solid complexes RES₂CN(C₄H₈)₃phen (RE=Gd, Yb, Ho) in a nitrogen atmosphere with certain amount of oxygen at 600–1100 °C. The as−prepared Gd₂O₂S:Yb_0.06Ho_0.02 exhibits a strong green up−conversion luminescence under 980 nm IR excitation. The intensity of the green emission component is 37.4 and 53.4 times more than that of the red and NIR emissions, respectively. It is indicated that the material is of excellent color purity. Under an IR excitation density of 34.75 mW/mm² with a laser beam diameter of 1 mm, the material exhibits an up−conversion luminescence brightness of 43.68 Cd/m².