The Preparation Of Rare Earth Doped Zinc Borate Luminescence Materials And Spectral Studies

Luminescent materials of borate matrix have been received great attention due to their low synthesis temperature, chemical stability. By motivated with the mechanism research between materials synthesis process and luminescence properties, series of typical rare earth ions doped zinc borate phosphors are prepared. The main contents of this dissertation are arranged as follows:In chapter1, the basic photoluminescence (PL) properties materials and some rare-earth ions such as Eu3+. Eu2+and Tb3+are reviewed, as well as the recent research progress based on borate system used for lamp and PDPs is also presented.In chapter2, Eu3+doped2ZnO·2.2B2O3·3H2O. was synthesized by hydrothermal method. The morphology, crystal phase and luminescent properties of the sample were characterized by scanning electronic microscopy (SEM), X-ray diffraction (XRD) and fluorescence spectrometer, respectively. The SEM image shows the particle size of the as-prepared powder is ranged from0.1to1μm. The crystal phase of the as-prepared powder is toward to glass state with the increasing of Eu content. The fluorescence spectra of Eu-doped2ZnO·2.2B2O3·3H2O reveals that the emission intensity of Eu3+excited by253nm (corresponding to the charge transfer band of Eu3+-O2-) is much stronger than it excited by394nm. The optimism doping concentration is24%(molar ratio Eu:Zn=24%). When the annealing temperature is increased up to400℃, decrease in the emission intensity of Eu3+and appearance of a new fluorescence peak (he peak position at470nm) assigned to the emission of Eu2is observed.In chapter3, the samples of2ZnO·2.2B2O3·3H2O:Eu3+were prepared by hydrothermal method by adjusting the pH value of precursor solution with the ammonia. The crystal phase and luminescent properties of the samples were characterized by X-ray diffraction (XRD) and fluorescence spectrometer. Results of X-ray diffraction analysis showed that the degree of crystallization of the samples was influenced by the concentration of pH value in precursor solution. The samples were crystallized best when the pH value was around7. The excitation spectra showed that the charge transfer band of Eu-O located at262nm when pH=5.7. This may be due to the band length (I614/I589) increased with the increasing of pH value(pH>5.7). Meanwhile, the ratios of I614/I589of the samples synthesized in the condition of pH=5.7～6.9increased faster than samples synthesized in the condition of pH=4.0～5.7.6.9～9.3. The emission spectra showed that the emission intensity of Eu3+of the sample synthesized at pH=8.1was the strongest.In chapter4. the samples of Eu3+and Tb3+co-doped2ZnO2·2.2B2O3·3H2O. were synthesized by hydrothermal method. The crystal phase and luminescent properties of the sample were characterized by X-ray diffraction (XRD) and fluorescence spectrometer, respectively. The crystal phase of the as-prepared powder is toward to glass state with the increasing of Eu and Tb content. The luminescent properties of the samples were characterized by fluorescence spectrometer. The fluorescence spectra of Eu3+and Tb3+. co-doped2ZnO·2.2B2O3·3H2O reveals that that energy transfer happened between Tb3+and Eu3+. The intensity of Eu3+was increased with the concentration of Tb3+while keeping the same Eu3+doped concentration of. When the samples were excited under393nm. the luminescence intensity of Eu3+was increased in liner relationship with the increase of the doped Tb3+concentration. The samples were excited under351nm. the rate of intensity of Eu3+increased is almost equal while the concentration of Tb3+was small. While the rate of intensity of Eu3+increased is much bigger for the larger Tb3+dopant concentration. It can be attributed to energy transfer is more effective for the short distance of Eu-Tb in high Tb3+dopant concentration.