Controllable Synthesis And Optics Properties Study On The RE Ions Codoped Y₂O₃and YPO₄Fluorescence Material

Rare earth （RE） ions doped fluorescent material has the properties of high emissionefficiency, highly controllable colours, thermal and mechanical stability, have been widelystudied in the field of lighting, display, sensors and detection. Further research of variety REions co-doped system was studied by the researchers. It was found that the emitting color andintensity are not a linear combination of that of single RE ion doped system. Strong andcomplex energy transfer was detected. But the study of microstructure, optical properties andthe influence of microstructure to optical properties were rarely reported. And the study ofrelated mechanism was still infrequent.Many RE ions co-doped Y₂O₃and YPO₄fluorescent materials were synthesized byhydrothermal method and high temperature pyrolysis in this thesis. These two kinds ofmaterials were regarded as study object. And the microstructure, optical properties and relatedmechanism were discussed. The conclusions can be given as follows:（1） Y₂O₃: Pr³⁺, Eu³⁺micro-sheet fluorescent material has been controllable synthesized.The structure and fluorescent mechanism were studied. The emitting and excitingmechanisms were based on the simplified energy level. And the analysis results showed that:the energy transmission between Pr³⁺and Eu³⁺, the crystallinity of the synthesized crystal andthe symmetry of central ion have a combined relationship to the monotonous change of theemission intensity of Eu³⁺ion. The competition existed among these three factors. Theleading factors varied in different conditions.（2） Y₂O₃: Ce³⁺, Eu³⁺fluorescent material has been controllable synthesized. Through itsmicrostructure and luminous mechanism study, we found that the concentration of the dopedion have obvious influence to the microstructure of fluorescent particles. From the phaseanalysis we found that both the ball and tubular particles are all polycrystalline structure. Thefluorescence spectra showed that the Ce³⁺and Eu³⁺co-doped material mainly emitted614nmred emission and587nm orange emission. And the concentration of Ce³⁺had a stronginfluence to the fluorescence emission intensity of Eu³⁺.（3） YPO₄: Eu³⁺, Ce³⁺micro sphere fluorescent material has been controllable synthesized.Under254nm UV excitation, the obtained micro sphere had a strong red-orange relativefluorescence emission. And this red-orange relative emission intensity enhanced markedlywith the increasing of Ce³⁺ion content. Based on the analysis of fluorescence decay curve,excitation spectrum, fluorescence spectrum and the simplified energy level of Eu³⁺and Ce³⁺,the possible excitation and emission mechanism was discussed. Finally, energy transferbetween Eu³⁺and Ce³⁺was confirmed by calculating the effective life time of the excitedstate and fitting the decay curve by a double parameters decay function.（4） YPO₄: Tb³⁺, Ce³⁺micro sphere fluorescent material has been controllable synthesized.Based on the structure analysis, a moderate amount of Tb³⁺and Ce³⁺doping did not destroythe characteristic phase structure. The analysis was based on fluorescence spectrum, emissionspectrum and XRD, which suggested that: the relative544nm green light intensity of YPO₄:Tb³⁺, Ce³⁺micro sphere can be tuned by changing the content of the co-doped Ce³⁺. Finally,energy transfer betweenTb³⁺and Ce³⁺was confirmed by calculating the effective life time ofthe excited state and fitting the decay curve by a double parameters decay function. （5） YPO₄: Yb³⁺, Ho³⁺, Tm³⁺micro-nano tube fluorescent material has been controllablesynthesized. Under the near infrared excitation, the obtained YPO₄: Yb³⁺, Ho³⁺, Tm³⁺canemitted red, green, blue and a795nm near infrared radiation. Based on the discussion ofstructure and properties of the Tm³⁺, Ho³⁺, Yb³⁺co-doped YPO₄micro-nano tubes, the resultsshowed that: temperature of the hydrothermal reaction had an obvious influence to theemission spectrum of the fluorescent material, but an unobvious influence to the structure.Under the same reaction temperature, the intensity of the emission peak didn’t increasemonotonously with the increasing content of the doped RE ion. But the intensitymonotonously changed due to the concentration quenching and cross relaxation. The possibleup-conversion mechanism was discussed in this thesis.