Study On Rare Earth Doped Silicate Electron Capture Materials And Their Luminescent Properties

The photo-stimulated luminescence (PSL) materials show a potential of optical storage due to their advantages, such as high write/read/erase rate (ns), short infrared response time, infinite read/write cycle life, and wide infrared response time range (0.8-1.6 μn), Therefore PSL materials have found a plethora of important applications, such as laser label, optical communications, storage, displays, and imaging techniques. Electrons and holes can be trapped in PSL materials in charging processes by exposed them to ultraviolet (UV) or visible light, and subsequently released by thermal activation or infrared stimulation through recombining elections and holes to generate visible PSL, Up to the present, the best known PSL materials with largest storage capacity have been alkaline sulfides, to best our knowledge, the poor chemical and thermal stabilities of alkaline sulfides in air can’t enough satisfy urgent need for application. In the past decades, many efforts have been made to discover suitable PSL material with super chemical and thermal stabilities. Therefore, additional studies on developing more stable PSL materials are still significant. Fortunately the phenomenon of PSL was observed in some silicate-based phosphors, PSL materials of silicate have attracted much research interest attribute to their excellent chemical and thermal stability.Rare earth Eu2+ doped RSrSiO4:Eu2+(R=Sr/Li2) is well known commercial phosphor, which can be excited with UV or blue light and give a broad emission band covering the region from 500 to 700nn. In this paper, Li2SrSiO4: Eu2+, La3+ phosphor with the orange-yellow PSL phenomenon were synthesized by the solid-state reaction, and the doping ratio of Eu2+ and La3+ was optimal selected according to multiple experimental results. In order to explore the PSL processes. Li2SrSiO4 Eu2+ phosphor was also prepared additionally. The photoluminescence (PL) and PSL properties of all these samples have been investigated. TL curves have been recorded, and the depths of different traps on co-doping La3+ ions have been quantitative analyzed. The mechanism for the origin and enhancement of PSL phenomenon was also discussed briefly.(1) Intensity of the LLL and PSL were significantly enchanced by doping the La3+ions in the sample β-Sr2SiO4:Eu2+. The time of LLL had an obviously enchancement. To some extend, the intensity of PSLhad large promoted, due to the incorporation of La3+ ions. So electrons were easily to be captured by the traps in the β-Sr2SiO4:Eu+.(2) The sample with different dopant of ions (La3+/Nd3+/Dy3+ /Tm3+) have different structure of trap.By constract, the sample with doping La3+ ions have a excellent PSL property. Because the the number of traps with different depth were a significantly increaced by La3+ions. Meanwhile the sample with Nd3+/Dy3+ ions exhibits a excellent LLL performance, and the Dy3+ ions is better. Howere, the sample with Tm3+ ions have no obvious enhancement in PSL or LLL.(3) The high-brightness orange-yellow PSL have been observed in Li2SrSiO4:Eu2+ phosphor when La3+ is co-doped upon infrared stimulation at 980nm after pre-irradiation with UV light. Both the PL and PSL spectra of Li2SrSi04: Eu2+, La3+ reveal that only one asymmetric broad emission band located at 567nm was observed, With the increasing number of trap caused by La3+ ions, PSL property of the co-doped samples has a large improvement. The results indicate that V。- as electrons traps is responsible for PSL of single/co-doped samples. A novel orange-yellow emitting LLP with excellent afterglow properties has been designed, synthesized and characterized. A significant enhancement of LLL property is achieved by doping Dy3+ ions Li2SrSiO4: Eu2+ phosphor. As well as photoluminescence spectrum and long-lasting luminescence spectra is similar, suggesting that LLL is due to the 4f65d1â†'4f7transitions of Eu2+ ions center. With the increasing number of trap A caused by Dy3+ ions, long-persistent property of the co-doped samples has a large improvement. A possible afterglow mechanism is proposed and the process of LLL is explained. The brand new LLL material exhibiting 15 hours LLL will have potential to be applied in many different fields.