Translated Abstract
In this paper, the current situation and development of phosphors were reviewed systematically. Characteristic of phosphors, preparing methods and application prospect of phosphorescence systems of alkaline earth aluminate, silicate and titanate were discussed and several valuable research results were obtained. The luminescent mechanism of this kind of phosphor was discussed too.The high quality SrAl2O4:Eu2+, Dy3+ and Sr2MgSi2O7:Eu2+, Dy3+ phosphors have been prepared by rare earth directly doped technique and solid sintering technology. On the basis of theoretically research and experimental quest, two times sintering method at the presence of carbon as reductant has been got. This method can decline the phosphors‘ cost, simplify the preparation method and improve luminescence efficiency. By considering practical application of phosphors,red long persistence phosphor of CaTiO3:Pr3+ has been prepared which can widen the application of phosphors. According to the measurement and analysis about luminous performance and long persistence of samples at different sintering temperature, the optimum experimental schemes for preparing phosphors have been proposed, and as a result, the optimum technique parameter, such as sintering temperature and time, have been obtained. The impact of rare earth content and boracic acid content on performance of phosphor have been systematically investigated and the optimum contents have been obtained.X-ray diffraction analysis for prepared phosphors proved that the basic texture was SrAl2O4 monoclinic crystal structure, Sr2MgSi2O7 tetragonal crystal structure and CaTiO3 orthorhombic crystal structure respectively. It was indicated that the phases were identical to the phases of our anticipative prepared phosphors. The crystal structure wasn’t changed by the rare earth dopant notably.It was found that the phosphor’s exciting spectrum and emission spectrum were broad by measuring its spectrum characteristic. The results showed that long persistence of SrAl2O4：Eu2+, Dy3+Sr2MgSi2O7：Eu2+, Dy3+phosphors typically belonged to the 4f7 (8S7/2)—4f65d transition of Eu2+. Moreover, long persistence of CaTiO3:Pr3+ phosphor was due to a transition from 1D2—3H4 of Pr3+. The exciting peak wavelength of them was 334nm,388nm,323nm respectively. Emission peak wavelength of them was 509nm,463nm,610nm respectively.Luminescence decay of phosphor consisted of the initial fast process and the later extremely slow process. The long persistence of phosphors can last over 20 hours, 10 hours, 5 minutes in the light perception of the human eye respectively. After having observed their thermoluminescence spectrum, SrAl2O4:Eu2+, Dy3+ has one TL peak at 378K, Sr2MgSi2O7:Eu2+, Dy3+ has two TL peaks at 445K and 499K, and the TL peaks of CaTiO3:Pr3+ were at about 290K and 325K. It was proved that the characteristics of long persistence were caused by very deep electron traps which were corresponding to TL peaks.
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