Synthesis of Y₂Zr₂O₇:Tm³⁺ phosphors by sol-gel method and its photoluminescence

(Y_1-xTm_x)₂Zr₂O₇(x=0.005, 0.01, 0.03, 0.05) phosphors are synthesized by sol-gel method using citric acid as complexing agent. The structure, morphology and luminescence spectra of the samples are investigated by X-ray diffraction (XRD), SEM and fluorescence spectrophotometer, respectively. The XRD patterns indicate that the structures of samples are characterized by single-phased fluorite structure. The crystal structure has not been changed by the invasion of Tm³⁺. The best luminescence performance is obtained for the (Y_1-xTm_x)₂Zr₂O₇(x=0.01) by sintering at 1 000 ℃ under the excitation wavelength at 359 nm. The emissions of 1¹D₂→³F₄ and ¹G₄→³H₆ transitions of Tm³⁺ are observed by studying the mechanisms of the two emissions. The emission intensity of 1¹D₂→³F₄ transition increases with the adding of Tm³⁺-doping concentrations, then reaches the maximum when Tm³⁺ concentration is at 1 mol % and decreases with increasing Tm³⁺-doping concentrations, which indicates that the concentration quenching is active when x > 0.01.