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After trace Sm~(3+) ions and Gd~(3+) ions doping, the emission intensity of red phosphors Y_2O_2S∶Eu~(3+) was enhanced and the voltage character (relation between emission intensity and excitation voltage) was improved while the other properties of physics and chemistry were not changed. The origins of enhancement and improvement are discussed. Probably the distortion and the defect of crystals are decreased by the substitution of Gd~(3+) for Y~(3+) instead of Eu~(3+) for Y~(3+), and thus the Eu~(3+) crystal field is improved, and radiationless process and energy loss resulted from crystal defect are weakened, which leads to increased luminescence intensity and voltage character improvement. The overlapping fluorescent spectra of Y_2O_2S∶Sm~(3+) emission and Y_2O_2S∶Eu~(3+) excitation as well as Eu~(3+) excitation spectra containing Sm~(3+) excitation transitions spectra lead to the possibility of resonance energy transfer from Sm~(3+) ions to Eu~(3+) ions, and the sensitization of Sm~(3+) ions to Eu~(3+) ions is achieved effectively.
After trace Sm ~ (3+) ions and Gd ~ (3+) ions doping, the emission intensity of red phosphors Y_2O_2S:Eu ~ (3+) was enhanced and the voltage character (relation between emission intensity and excitation voltage) was improved Probably the distortion and the defect of crystals are decreased by the substitution of Gd ~ (3+) for Y ~ (3+) instead of Eu ~ (3+) for Y ~ (3+), and thus the Eu ~ (3 +) crystal field is improved, and radiationless process and energy loss resulted from crystal defect are weakened, which leads to increased luminescence intensity and voltage character improvement. The overlapping fluorescent spectra of excitation spectra containing Sm ~ (3+) excitation transitions spectra of to ~ (3+) excitation and Eu2 + possibility of resonance energy transfer from Sm ~ (3+) ions to Eu ~ (3+) ions, and the sensitization of Sm ~ (3+) ions to Eu ~ (3+) ions is effective.